UNIVERSITY OF HAWAII TELESCOPES AT MAUNA KEA OBSERVATORY USER MANUAL Fourth Edition, April 1996 Last modified, June 1997 Contents 1 INTRODUCTION 1 1.1 General...........................................................1 1.2 About this Manual ................................................1 1.3 Observing Time-Policy and Procedures .............................1 1.3.1 Students and Assistants .....................................3 1.3.2 Information before Arrival...................................3 1.3.3 Colloquia....................................................3 1.3.4 Reports to the Director .....................................3 1.3.5 Publications and Acknowledgments.............................3 1.4 Newsletter........................................................4 1.5 Information for Visiting Observatory..............................4 1.5.1 Transportation from Hilo to Hale Pohaku and Mauna Kea Observatory..............................................4 1.6 Accommodation-The Mid-level Facility, Hale Pohaku.................8 1.6.1 Telephone Service............................................8 1.6.2 Mail Service.................................................8 1.6.3 Library......................................................8 2 VISITING OBSERVER EQUIPMENT 11 2.1 Packing Goods for Shipping.......................................11 2.2 Transport........................................................11 2.3 Access to Domes..................................................11 2.4 Customs Regulations for Observers from Foreign Countries.........12 2.4.1 Equipment Eligible for Customs Duty Exemption...............12 2.4.2 Equipment to be Consumed or to Remain in the United States..12 2.4.3 Returning Equipment to Country of Origin....................13 2.4.4 Additional Information......................................13 3 WEATHER AND SITE QUALITIES 14 3.1 Weather..........................................................14 3.2 Cold-weather Gear................................................14 3.3 Site Quality.....................................................14 4 SUMMIT FACILITIES AT THE UH TELESCOPES 18 4.1 Computers........................................................18 4.2 Mechanical Shop..................................................19 4.3 Electronics Shop.................................................19 4.4 CCD/IR Dewar Lab.................................................19 4.5 Power at the Summit..............................................19 4.6 Living Facilities in the 2.2-m Building..........................20 4.7 Loaned Facilities................................................20 5 SUPPLIES 21 5.1 Dry Ice...........................................................21 5.2 Liquid Nitrogen and Liquid Helium.................................21 5.3 Pumping and Transfer Tube Information.............................21 6 TELESCOPES 22 6.1 61-cm(24-inch) Telescope..........................................22 6.2 2.2-m (88-inch) Reflector.........................................22 6.2.1 Telescope Control System......................................25 6.2.2 Cassegrain Observing Platform.................................25 6.2.3 Control Room..................................................29 6.2.4 Coude Focus...................................................29 6.2.5 Fiber-optic Audio-Video link..................................29 7 INSTRUMENTATION 32 7.1 UH Telescope imaging scales and field sizes.......................32 7.2 2.2-m Cassegrain guider and instrument mount......................32 7.2.1 Instrument Rotator............................................32 7.2.2 CCD guider....................................................34 7.2.3 Instrument mount bolt circle..................................34 7.3 tcsi-user object selection interface..............................35 7.3.1 Telescope Control System Interface--tcsi......................35 7.3.2 Starting tcsi.................................................35 7.3.3 tcsi windows..................................................35 7.4 f/10 secondary....................................................38 7.5 f/31 secondary....................................................38 7.5.1 f/31 hexapod and Physik Instrumente tip-tilt platform.........39 7.6 Focusing..........................................................41 7.6.1 Focus sensitivity to temperature..............................41 7.6.2 Focus settings for common instruments.........................41 7.6.3 Focusing the f/31 secondary mirror............................43 7.7 CCDs..............................................................43 7.7.1 Tektronix 2048 x 2048 CCD.....................................43 7.7.2 Orbit 2048 x 2048 CCD.........................................44 7.7.3 Loral 2048 x 2048 CCD.........................................44 7.7.4 8192 x 8192 mosaic CCD camera.................................44 7.8 Filter Wheels and Filter Slide....................................44 7.9 Optical/UV filters................................................48 7.10 Infrared Cameras.................................................48 7.10.1 QUIRC........................................................50 7.11 f/10 Faint Object Spectrograph (FOS).............................50 7.12 f/10 Wide Field Grism Spectrograph (WFGS)........................54 f/31 High Angular Resolution Imaging Spectrograph (HARIS).....54 7.13.1 HARIS schematic overview.....................................55 7.13.2 Cameras, Collimators and Slits...............................55 7.13.3 Gratings and Resolution......................................55 7.13.4 Selecting Grating Tilt Angles................................58 7.14 f/31 JHK cross dispersed spectrograph-KSPEC......................58 7.15 Optical Photometer and Photon-Counting System....................60 7.16 2.2-m Coude f/34 Spectrograph....................................60 7.16.1 Coude Slit Instrumentation..................................60 7.16.2 Comparison Sources..........................................60 7.16.3 Filter Mounting.............................................60 7.16.4 Coude Cameras...............................................60 7.16.5 Coude Gratings..............................................61 7.16.6 Grating Angle...............................................61 A Names and Addresses 67 A.1 Institute for Astronomy (Honolulu) Staff.........................67 A.2 Institute for Astronomy (Hilo and Summit Staff)..................68 A.3 Mauna Kea Support Services.......................................68 A.4 Airport-General Lyman Field, Hilo HI 96720.......................68 A.5 Hilo-based Trucking Firms........................................69 A.6 Customs..........................................................69 A.7 4-wheel Drive Vehicle Rentals-Big Island.........................69 A.8 Accommodation in Hilo............................................70 B Forms 71 B.1 Observing Time Request Form......................................71 B.2 Observer's Report................................................77 C Mauna Kea Support Services 78 C.1 Lodging Service..................................................78 C.2 Library..........................................................79 C.3 Offices..........................................................79 C.4 Locker Services..................................................79 C.5 Mail Service.....................................................79 C.6 Telephone Service................................................79 C.7 Water, Electricity and Heat......................................79 C.7.1 Vehicle Gasoline...........................................80 C.7.2 Fire.......................................................80 C.7.3 Food Service...............................................80 D Mountain-top Policies 81 E Safety Regulations for observers at UH Telescopes 83 F Acclimatization - the 24-hour rule 85 G Visitor information and Costs 86 G.1 Acclimatization...................................................86 G.2 High Altitude Health Tips-How your body functions at high altitudes........................................................86 G.3 Mauna Kea Summit Information......................................87 G.3.1 Preparing for Severe Weather................................87 G.3.2 Preparing for High Altitude.................................88 G.4 Visitor Information-Onizuka Center for International Astronomy....88 G.4.1 Official Summit Tours.......................................88 G.4.2 Friday Public Information Night (Introduction to Astronomy).88 G.4.3 Star-gazing from the Summit.................................89 G.4.4 Finding Mauna Kea...........................................89 G.4.5 Caution!....................................................89 G.5 Information and Costs for Visiting Observers at UH Telescopes.....89 G.5.1 Direct Costs................................................89 G.5.2 Vehicles....................................................90 G.5.3 Cryogens....................................................90 G.5.4 Visitor Equipment...........................................90 List of Figures 1.1 The location of the institute for Astronomy in Honolulu............2 1.2 Eight main islands of the State of Hawaii, and the City of Hilo....5 1.3 Road maps of the island of Hawaii, and access routes to Mauna Kea..6 1.4 Map of Mauna Kea Access Road from the Saddle Road to the summit....7 1.5 Mauna Kea Observatory site map.....................................9 3.1 Mean temperatures and wind velocity at Mauna Kea, 1965-1969.......15 3.2 Wind velocity at Mauna Kea Observatories-1993.....................16 3.3 Temperatures at Mauna Kea Observatories-1993......................17 6.1 Layout of the instrument mounting flange on the 61-cm telescope...23 6.2 Optical configuration of the 2.2-m telescope......................25 6.3 Layout of the 2.2-m telescope dome................................26 6.4 Layout of the 2.2-m Cassegrain instrument mounting flange.........27 6.5 Layout of the 2.2-m broken Cassegrain instrument mounting flange..28 6.6 Block diagram showing the audio and video equipment at the summit.30 6.7 Block diagram showing the audio and video equipment at Hale Pohaki31 7.1 UH 2.2-m Cassegrain guider and instrument racks, viewed from below............................................................33 7.2 UH 2.2-m User interface tcsi......................................36 7.3 tcsi SM f/10 cassegrain display...................................37 7.4 tcsi SM f/31 cassegrain display...................................37 7.5 2.2-m f/31 top end with hexapod and PI platform...................41 7.6 tkhex - focus window..............................................43 7.7 tkhex - collimation window........................................44 7.8 View of the CCD user interface, which runs on a NeXT workstation..45 7.9 Physical characteristics of typical CCD dewars....................46 7.10 Measured quantum efficiency of Tektronix 1024 x 1024 and Orbit 2048 x 2048 CCDs...........................................47 7.11 Transmission curves of optical/UV filters........................49 7.12 Transmission curves of broad-band infrared filters...............51 7.13 Transmission curves of narrow-band infrared filters..............52 7.14 Front view of the f/31 HARIS spectrograph with the components and optical paths indicated......................................56 7.15 Side view of the f/31 HARIS spectrograph with the components and optical paths indicated......................................57 7.16 Spectral image of an AO calibration star.........................59 List of Tables 1.1 Due dates for UH Observing Requests..................................3 6.1 2.2-m primary and secondary mirror dimensions and curvatures........24 7.1 Imaging scales and field sizes......................................32 7.2 2.2-m. primary and f/31 secondary mirror optical specifications.....40 7.3 PI S-380 Characteristics............................................40 7.4 Hexapod Specifications..............................................40 7.5 Common IfA instrument and mount dimensions along optical axis.......42 7.6 Common IfA instrument configurations and focus settings.............42 7.7 CCD characteristics.................................................48 7.8 Faint Object Spectrograph Characteristics...........................53 7.9 Faint Object Spectrograph Gratings.................................53 7.10 Wide Field Grism Spectrograph Characteristics......................54 7.11 Wide Field Grism Spectrograph Dispersion Characteristics with Zeiss 135 mm lens..................................................54 7.12 f/31 HARIS Spectrograph Components.................................62 7.13 f/31 HARIS Spectrograph Gratings and Dispersions...................62 7.14 f/31 HARIS Spectrograph Grating Settings...........................63 7.15 KSPEC Orders (0.96" slit, 2.2-m telescope, 3 min exposure).........63 7.16 Available Slits for KSPEC..........................................64 7.17 Optical photometer apertures.......................................64 7.18 Coude Spectrograph Characteristics.................................65 7.19 Examples of Coude Grating Angles...................................65 7.20 Coude Spectrograph Gratings and Dispersions........................66 Chapter 1 INTRODUCTION 1.1 General This Manual is intended to assist astronomers wishing to use the University of Hawaii (UH) facilities at Mauna Kea Observatory (MKO). These telescopes are run primarily as university research facilities (rather than visitor facilities). However, proposals to study Solar system objects with the 2.2-m telescope are welcomed from investigators external to the University of Hawaii. Proposals to use the 2.2-m telescope to study objects beyond the Solar System which have Principal Investigators external to the University of Hawaii, are not normally considered eligible for consideration by the Time Allocation Committee. External proposals for the 61-cm telescope will only be considered under special circumstances. The UH telescopes are operated by the Institute for Astronomy (IfA) of the University of Hawaii. Institute headquarters are located on the University campus in Honolulu, on the Island of Oahu. A map showing the route from Honolulu airport to the Institute for Astronomy is shown in Figure 1.1 (not included). The telescopes are located at the Observatory on the summit of Mauna Kea on the Big Island of Hawaii-about a 2 hour drive from Hilo. The University of Hawaii's 2.2-meter telescope is located at Mauna Kea Observatory, at an altitude of 4,214 m (13,824 ft), latitude+ 19 49134", and longitude 155 28'20" (10h 21m 53s) West. 1.2 About this Manual Because of the cost and time involved in producing printed versions of this manual, the printed version will be updated relatively infrequently. However, we intend to keep the on-line version of this manual updated as changes occur. This is the most up-to-date version of the manual will be accessible from the World Wide Web. The URL of the home page for the 2.2-meter telescope is: http://www.ifa.hawaii.edu/88inch and the URL for this manual is: http://www.ifa.hawaii.edu/88inch/manuals/user.pdf. Also available from the home page are numerous instrument manuals, which contain more in-depth information. 1.3 Observing Time-Policy and Procedures Requests for the use of UH facilities at MKO should be made to the Director of the IfA as far in advance as possible. Scheduling periods (six-month semesters) and the deadlines for receipt of observing requests are shown in Table 1.1. If the deadline falls on a weekend or holiday, proposals are due on the next working day. As the UH telescopes are not supported primarily as visitor facilities, the Director suggests that only experienced observers apply for telescope time. Those asking for time on the 61-cm telescope should be thoroughly familiar with similar instrumentation at other sites. Because of staff limitations, the maximum observing time per night is normally 11 hours. Observing beyond 11 hours is only possible with the agreement of the Telescope Operator, and should be negotiated in advance (it must not be taken for granted). The 11 hour observing period normally commences around sunset, but can be adjusted to some extent, to suit the observer's requirements, by negotiation with the Telescope Operator. Daytime observing with the 2.2-m telescope is normally not possible. Table 1.1: Due dates for UH Observing Requests ___________________________________ Observing Period | Due Date ____________________|______________ February-July | September 15 August-January | March 15 ____________________|______________ Applications are to be made on a standard "Observing Time Request" form, a copy of which may be found in Appendix B. This form was constructed using the LATEX typesetting program; the applicant can insert the required information into the source file and subsequently print the completed application. Electronic copies of the "Observing Time Request" form may be obtained from the URL listed in Section 1.2. Applicants must limit their scientific justification to one page of text. An additional page of figures may be included. References do not count against the page limit. Successful applicants are informed of their assigned observing time about 4 weeks before the beginning of the semester in which their observing run occurs. Any changes which are substantially different from the proposed observing program or personnel changes from those listed in the original application must be approved by the Director. 1.3.1 Students and Assistants Students and assistants may accompany visiting observers, but because of limited accommodations at the mid-level facility, special permission must be requested on the "Observing Time Request" form if the total number exceeds three. Assistants sent to observe in place of the principal scientist will not be accepted unless it is made clear that full collaboration in research and joint authorship in publication is intended. The granting of observing time to visiting observers and their students does not imply an obligation on the part of the Institute for Astronomy to continue granting time in order for students to complete their thesis research. 1.3.2 Information before Arrival If observing time is granted, each visiting observer is required to complete the on-line "Visiting Observer Information Form" at http://www.ifa.hawaii.edu/cgi-bin/visitingobserver.form at least 3 weeks before his/her scheduled arrival. If any equipment is going to be sent to the telescope, this should be directly coordinated with the UH Telescope Superintendent. 1.3.3 Colloquia We may ask observers to whom we have granted time on the 2.2-m telescope to spend a day in Honolulu, either before or after their observing run, to present a colloquium and discuss their research with staff of the Institute for Astronomy. 13.4 Reports to the Director Visiting observers will be requested to send a letter report to the Director setting out any comments about the observing conditions and the observer's overall reaction to the operation of the facility. In addition, a short "Observing Report" form (Appendix B, not included) should be submitted to the Telescope Manager. 1.3.5 Publications and Acknowledgments It is expected that the results of observations made using UH facilities at MKO will be published in the scientific literature. All publications based principally on research results obtained with the University facilities shall carry a credit line and footnote of the following form: Title, Author, Home Institution and, as a footnote: Visiting observer, (named telescope) at Mauna Kea Observatory, Institute for Astronomy, University of Hawaii. Visiting observers who use the UH facilities at MKO for only a small part of a larger program should include a substantial acknowledgment to the University of Hawaii in their publication. Two preprints and five reprints of papers resulting from any observational work carried out on UH telescopes should be sent to the Director of the IfA. 1.4 Newsletter A telescope newsletter is produced two times per year, about three weeks before the telescope deadline. This newsletter contains updates on instruments and detectors, and serves as a supplement to this manual. The newsletter is distributed both via electronic mail and via regular mail. Requests for inclusion on the newsletter mailing list should be sent electronically to 88inch@ifa.hawaii.edu. 1.5 Information for Visiting Observers The international airport of Honolulu on the island of Oahu is served regularly by major airlines; regular and frequent interisland flights connect Honolulu with Hilo on the big island of Hawaii, as well as with other islands of the State of Hawaii (Figure 1.2 not included). Visiting observers should make their own hotel, airline, car rental, etc., arrangements, as the responsibilities of the Institute's office staff are necessarily limited to the immediate operation of the Observatory. Visitors should communicate their travel and observing plans to the IfA office in Hilo at least 3 weeks before their observing run, so that bookings can be made at Hale Pohaku and arrangements made for vehicle pick-up at the Hilo airport. Lists of pertinent names and addresses appear in Appendix A (not included. 1.5.1 Transportation from Hilo to Hale Pohaku and Mauna Kea Observatory Generally, observers on the 2.2-m telescope drive themselves in University 4-wheel drive vehicles which they pick up from and return to Hilo airport (see Fig. 1.2). This courtesy to visiting observers must be prearranged with the Telescope Superintendent. If no arrangement has been made, or no University vehicle is available for any reason, then transport is the responsibility of the observer. We usually require visiting observers on the 61-cm telescope to rent their own 4-wheel drive vehicles for the duration of their observing run. A list of agencies in Hilo that rent 4-wheel drive vehicles appears in Appendix A, and a number of agencies at the Hilo Airport rent ordinary standard-shift passenger cars (note that some of these agencies forbid driving on the Saddle Road). University vehicles are parked in the airport parking lot. The vehicle you will use will most likely be a Ford Explorer. One of these is blue in color (UH7, automatic), another is green (UH2, automatic) and the third is red (UH5, manual). Observers who have a large amount of equipment may make a special request to use one of the two white Chevrolet Suburbans (UH3 and UH4). The vehicles cannot be parked in a consistent location, so you have to search the parking lot for the vehicle. They are most easily identified by stickers on their rear (e.g., UH2, UH5), their State of Hawaii license plates, and the University logo on the side. The mid-level accommodation facility at Hale Pohaku is reached by a 90 minute drive over substandard roads (Figure 1.3 not included). The first 28 mile stretch, on State Highway 200 (Saddle Road) from Hilo to the turnoff (Humuula Sheep Station) is on a paved road, but with about one quarter of the asphalt surface in bad condition. Frequent curves and dips on this road restrict visibility, and drivers should be particularly wary of oncoming traffic; there is frequent heavy rain and fog which both makes the road slippery and restricts visibility. The most significant hazards are speeding and inattention at the wheel; observers should arrange their schedule to ensure they are well rested, and have ample time to make this journey. The route from the airport to the Saddle Road is shown in Figure 1.2. The turnoff from the Saddle Road to the access road to Mauna Kea is on the right-hand side, just before the 28 mile marker (there is no sign marking this turnoff as the road to Mauna Kea). The turnoff is opposite a small hill on the left which sticks out of the lava, and is also opposite a hunters' checking station. The connection to Hale Pohaku from Highway 200 is by a 10 km (6 mile) paved road (Figure 1.4 not included), which passes through open grazing land, and drivers should beware of stock wandering on the road. Although very steep in parts, this road can be negotiated by a standard shift automobile. Observers should check into the mid-level residence facility at Hale Pohaku before proceeding to the summit. More information about checking into Hale Pohaku may be found in Appendix C (not included). The 13.7 km (8.5 mile) road from Hale Pohaku to the summit should be driven only in 4-wheel drive vehicles. The road is rough in some places, and is always dusty. A 25 mph speed limit applies on this road. If dust masks are desired, they should be provided by the visiting observer. A map of the summit area is shown in Figure 1.5 (not included). When you drive down to the airport after your observing run, be sure that there is enough gasoline in the tank for the next observer to drive back to Hale Pohaku. We recommend filling the tank before leaving Hale Pohaku if the tank is less than half full. At the airport, try to park as close to the terminal building as possible, in a location that will be easy for the next observer to find. Visiting observers can occasionally obtain transportation to and from Hale Pohaku with the day crew, if it coincides with their regular weekday morning and afternoon schedule. Visiting observers will generally find it advantageous to be independent of the travel schedules of UH personnel. Use of gasoline at Hale Pohaku will be billed separately at the end of the observing run, using the information provided on the gas log sheet at Hale Pohaku. 1.6 Accommodation - The Mid-level Facility, Hale Pohaku Located at 2,835 m (9,300 ft) altitude, about midway between the turn-off from State Highway 20 and the summit of Mauna Kea, is the mid-level living facility, Hale Pohaku (Hawaiian for Stone House). This facility was named the "Onizuka Center for International Astronomy" (OCIA), after Ellison Onizuka, the Hawaiian born astronaut who was killed in 1986 when the Space Shuttle Challenger exploded. OCIA is run by Mauna Kea Support Services (MKSS), and provides accommodation for about 72 astronomers in single rooms with private bathrooms, and all meals including a night snack if desired. Details of the facilities available and charges are given in Appendices C and G. No toilet articles, cigarettes, stationery, postage stamps, etc. are available at Hale Pohaku, however - please bring a sufficient supply with you. 1.6.1 Telephone Service Hale Pohaku and the telescopes now have reliable microwave-linked telephone services. We expect that all these phone lines will be moved to fiber optic cable later in 1997. The telephones at the 2.2-meter telescope and in the 2.2 meter telescope office at Hale Pohaku (and the IRTF) are connected to the state's Hawaiian Advanced Telephone System (HATS). This system allows interisland calls to be placed toll-free using the state's digital microwave system. To access this system, you must dial "8" first instead of dialing "9" for an external line. To call a number at the IfA in Manoa, you therefore dial 8-1-808-956-xxxx. For local, interstate, or international calls you must dial "9." To call another phone that is also on the HATS system, you simply dial the last 5 digits of the number. For example, to call the 2.2 meter telescope from the UH office at HP, dial 4-4200. At Hale Pohaku, all toll calls are restricted. However, you can still make interisland calls using the HATS system by dialing "8" first. Observers are encouraged to use a credit card for interstate and international long distance calls. Calls to toll-free numbers are not restricted-dial 9-1-800 and the number. Interstate and international calls can be made from the summit at the 2.2-m and 0.6-m telescopes. Any long-distance calls dialed with "9" as the prefix must be logged at the telescope, and will be billed back to the originator of the call. There is no need to log any interisland calls made using the "8" prefix. 1.6.2 Mail Service There is no regular mail service to or from Hale Pohaku. Long-term visitors may receive mail brought from the Hilo office by the Day Crew. Mail should be addressed to the individual addressee, in care of the UH Telescope Superintendent at the Hilo office address (see Appendix A). 1.6.3 Library A small library of astronomical books, journals and photographic reference materials is located at Hale Pohaku. The principal holdings are: Annual Reviews of Astronomy and Astrophysics (all volumes) Applied Optics (Vol. 10, No. 1 [1971] to present) Astronomical Journal (Vol. 67, No. 1 [1962] to present) Astronomy (all volumes) Astronomy and Astrophysics (all volumes) Astronomy and Astrophysics Supplement (all volumes) Astrophysical Journal (Vol. 105 [1947] to present) Bulletin of the American Astronomical Society (all volumes) Icarus (Vol. 8, No. 1 [1968] to present) Publications of the Astronomical Society of the Pacific (Vol. 76 No. 448 [1964] to present) Science (Vol. 175, No. 4017 [1974] to present) Scientific American (Vol. 222, No. 1 [1970] to present) Sky and Telescope (Vol. 33, No. I [1967] to present) Henry Draper Catalog, Smithsonian Astrophysical Observatory Star Catalog and Charts, Vehrenberg's Stern Atlas (Parts I, II, and III), Atlas Coeli 1950.0, and other miscellaneous reference publications. the Palomar Sky Survey prints (plus southern extension) the ESO/SER Southern Sky Survey (film copy) the new Palomar Sky Survey (film copy). Since there is no resident librarian at Hale Pohaku, books and papers cannot be loaned out and must remain in the library at all times. A photocopying machine is available. A workstation is also available in the library, for access to on-line catalogs. Chapter 2 VISITING OBSERVER EQUIPMENT 2.1 Packing Goods for Shipping Observers and their equipment must be prepared to endure a rather severe shaking each time they travel from Hilo to the summit. The consequences of the rough road are normally much more serious for delicate equipment than for personnel. Equipment sensitive to dust should be wrapped and sealed in plastic bags inside the shipping crates. Delicate components should be packed in small boxes and hand carried from Hilo to the summit. Normal electronic and mechanical components less sensitive to shock will usually survive the trip to the summit intact, but should be especially well packed - better than one would normally pack for transportation by a commercial shipper. 2.2 Transport If equipment is in quantities small enough to fit into a half-ton truck, Observatory personnel can normally transport it to the summit, but usually at least one day after it arrives at the Hilo airport. Visiting observers requesting transport of their equipment should time its arrival in Hilo to precede their need for it at the summit by 4 to 5 days. Crates should have dimensions no larger than 1.2 m (4 ft) wide and 2.4 m (8 ft) long; height is unrestricted within reason. For ease of handling, crates should weigh no more than 100 kg (220 lb). Visiting observers who have large amounts of equipment to transport must arrange their own transportation and arrange for payment directly to the trucking company. Shipment of scientific equipment and requests for its transport to the summit must be coordinated with the UH Telescope Superintendent. All equipment shipped Air Freight, which has originated from within the United States should be shipped directly to Hilo on an airline having a freight office in Hilo (see Appendix A for names of airlines). This will ensure that the freight does not get lost in Honolulu and that freight charges are paid all the way to Hilo on the Big Island of Hawaii, rather than only to Honolulu on the Island of Oahu. Equipment originating from outside the United States, should be shipped to Hilo via Honolulu for Customs clearance (see the section below on Customs Regulations), with passage paid through to the final destination, Hilo. 2.3 Access to Domes Large pieces of equipment can enter the 2.2-m telescope building through a freight door 3.35 m (11 ft) wide and 3.28 m (10ft 9 in) tall; a 3600 kg (8000 lb) freight elevator connects the first and second floors with the observing floor. The elevator dimensions are 2.1 m (6 ft 11 in) high, 2.59 m (8 ft 6 in) wide, and 2.64 m (8 ft 8 in) deep. Mounted at the highest point in the dome is a 20 ton crane for moving heavy pieces of equipment into the dome from outside, and to any location on the observing floor. This crane is also used for moving equipment on to the Cassegrain observing platform when necessary. Visiting observers planning to use an electronics rack on the 2.2-m Cassegrain platform should provide eyes for attaching a cable from the crane. The Cassegrain platform at its lowest position is about 50 cm (20 in) above the concrete floor of the observing room. Electronic equipment can be mounted in the standard 19-inch racks attached to the Cassegrain rotator. Visiting observers bringing equipment weighing more than 50 kg (110 lb) are strongly urged to mount it on a pallet for handling with a forklift. There is no crane or other lifting device at the 61-cm telescope. 2.4 Customs Regulations for Observers from Foreign Countries All equipment and materials originating outside the United States and destined for Hawaii must be cleared through Customs in Honolulu, where fully staffed Customs offices are located. Since the Customs procedure is complex and best handled by a licensed Customs broker, the Institute has arranged for a local (Honolulu) Customs brokerage firm (Skelton-Kohara) to serve visiting observers (see Appendix A for address), although other brokers are available. It is extremely important that the visiting observer contact the Customs broker directly to engage his services and to obtain instructions. Some particularly important guidelines are indicated below. 2.4.1 Equipment Eligible for Customs Duty Exemption Scientific equipment that will be returned to the country of origin within one year of entry may be entered bonded and duty-free, provided it is cleared through Customs in Honolulu on entry and exit. The most important thing to keep in mind concerning such equipment is that it must be identifiable by the Customs agent when it enters Honolulu, and it must be reidentified when it goes out, in order to prove that the equipment has indeed left the country. In this regard, it is advisable to do the following when arranging shipment: 1. Crate those items for which duty exemption is requested. 2. For each crate, prepare a list showing the quantity, description (in English), and value of each piece of equipment in the crate. Number each crate, indicating that number on the appropriate list of contents. 3. Have the shipper prepare a cargo manifest (in English) so that it corresponds to the crate numbers and the content lists you have prepared. 4. Be sure that any airbills, waybills, etc. contain the following annotation: "NOTIFY INSTITUTE FOR ASTRONOMY, HILO, HAWAII [(808) 974-4205] AND (NAME, ADDRESS, AND TELEPHONE NUMBER OF YOUR CUSTOMS BROKER IN HAWAII)". 5. Airmail, without delay, copies of cargo manifests, carriers certificates, airbills/waybills, and crate content lists to both the Hilo Office and to your Customs broker. 6. Address and label your crates to include the following information: (1) Your return address; (2) Ultimate Destination: Institute for Astronomy, c/o (UH Telescope Superintendent's name) for (your name), Institute for Astronomy, 1175 Manono Street, Building 393, Hilo, Hawaii 96720, U.S.A., telephone (808) 9744205; (3) By way of; name, address, and telephone number of your customs broker; (4) This annotation: "SCIENTIFIC EQUIPMENT TO BE RETURNED TO COUNTRY OF ORIGIN WITHIN ONE YEAR OF ENTRY". 7. Arrange to be present in Honolulu at the import and export proceedings. 2.4.2 Equipment to be Consumed or to Remain in the United States Equipment of this nature should be declared and listed separately from that which will be returned to the country of origin within one year. The same procedure as that indicated above should be followed, with the exception that the notation shown in item (4) of the address instructions above should read: "TO BE CONSUMED" (or "TO REMAIN IN THE UNITED STATES"). 2.4.3 Returning Equipment to Country of Origin Before you leave Hilo, recrate your equipment in the same groupings in which it entered. Number the crates to coincide with the contents lists under which they entered. Address the crate showing: Ultimate Destination: (address, etc.). By way of (name and address of your Honolulu Customs broker). This will assure that the freight will go through Customs in Honolulu. Notify your Customs broker that you are ready to ship the equipment. Please do not leave Hawaii until the shipment has been cleared by Customs or until your broker has indicated that all is in order. 2.4.4 Additional Information Additional information concerning Customs regulations or procedures can be obtained from your Customs broker, or from the District Director of Customs (see Appendix A for address). It is the responsibility of the visiting observer to document any change in the number of items being exported from the number of items being imported. To simplify matters, we suggest that you use the same crates in both instances. Shipments to UH telescopes at MKO should be addressed as follows: Institute for Astronomy c/o (UH Telescope Superintendent's name) 1175 Manono St, Building 393, Hilo, Hawaii USA 96720 Telephone (808) 974-4205 By way of: Skelton-Kohara & Co., Customs Brokerage 736 South St, Room 201 Honolulu, Hawaii USA 96813 Telephone: (808) 524-2663 Fax: (808) 533-7097 Chapter 3 WEATHER AND SITE QUALITIES 3.1 Weather Minimum temperatures at the summit are generally at or below freezing, but rarely go lower than 10 C (14 F) during the winter. In the summer, they usually range around freezing. Daytime temperatures are normally about 10 C (50 F). Data on mean temperatures and wind speeds are shown in Fig3_1. Weather conditions can change very rapidly-you should always be prepared to leave the summit with little or no notice. Fig3_2 shows wind velocity measurements for the year of 1993. Notice that several times each year, the wind velocity exceeds hurricane force, with the peak velocity for 1993 being 130 mph. You must not attempt to go to the summit in these weather conditions. Always check the road conditions with the staff at Hale Pohaku if there is any question about the condition of the road. You may also call (808)969-3218 for recorded information about road and weather conditions. The current UKIRT weather is available at the URL http://www.jach.hawaii.edu/ cgi-bin/getwx.pl/UKIRT. When the conditions are bad or marginal, a notice board is usually positioned near the Hale Pohaku entrance-please read it. Fig3_3 shows temperature measurements for the year of 1993. The plot shows the diurnal temperature variation, as well as the seasonal variation. 3.2 Cold-weather Gear Clothing adequate to withstand sustained cold temperatures is essential for observations at the unheated 61-cm dome, for 2.2-m observers who expect to spend a significant time in the dome or on the Cassegrain platform, and for all observers moving between vehicles and domes. Cold-weather clothing can be borrowed from MKSS at Hale Pohaku, for a small rental fee to cover cleaning costs. As mentioned previously, nighttime temperatures seldom drop very low, but high winds and freezing rain are common during the winter months and are possible any time. Several rooms in the 2.2-m building are heated, including a working area where instruments can be assembled. The 61-cm dome is not heated. 3.3 Site Quality A description of conditions on Mauna Kea during the construction of the Observatory can be found in Sky and Telescope, 36, September 1968; astronomical characteristics of the site are described in PASP, 85, June 1973. Typical zenith dark sky brightness values for Mauna Kea are 22.4, 21.1, c 20.3, 16, 14.5, 14.0, and 13.5 mag arcsec^2. A good summary of the sky brightness at optical wavelengths, the transmission at infrared wavelengths and extinction is contained in the CFHT User manual, and users are referred to this for additional data. Chapter 4 SUMMIT FACILITIES AT THE UH TELESCOPES 4.1 Computers The computer facilities are being continually upgraded to meet the changing needs of observers. The 2.2-m telescope is connected via an FDDI fiber-optic network to other telescopes on the summit and to Hale Pohaku, and from there, via a T-1 microwave link, to Manoa, and the internet. There are two ethernets in the 2.2-m telescope building. One ethernet connects all computers associated with the 2.2-m telescope, and another connects all computers associated with the 61-cm telescope (a fiber-optic cable connects the 61-cm telescope to the 2.2-m telescope). Thick and twisted pair ethernets are used at the 2.2-m telescope. Thin ethernet is used at the 61-cm telescope. Both ethernets have restricted access-communication is only allowed to a small number of trusted external sub-networks. Our principal disk storage area is located at Hale Pohaku. Observers are expected to transfer their data daily to Hale Pohaku to be written to tape. In those cases where a small detector is used, direct transfer of data to an external computer is practical, but we nevertheless strongly recommend that a tape is written as a backup. We presently use exabyte 8mm tapes for tape archiving of data. The most commonly used computers presently in use (and their functions) are listed below: A DEC LSI- 11/23 operating under FORTH. This dedicated machine is operated by the Telescope Operator (TO) for control of the 2.2-m telescope. An Dell 386/20 PC running MS/DOS which controls guiding at the coude focus. It can also provide guide signals for visitor instruments with their own guide camera (a video signal is required). A Sun SPARCstation 2 (tycho) with color monitor, 0.5 and 1.0 Gbyte disks, two CD-ROM drives, 48 Mbyte of memory, and a 300 dpi laser printer. The operating system is Unix (SunOS 4.1.4). This workstation interfaces directly with the Telescope Control System; the workstation is normally used by the Telescope Operator, who controls the telescope from a window on tycho's monitor. It also serves as a backup in case of failure of the other Sun at the summit. The HST guide star catalog is normally kept on-line in the CD-ROM drives, and is frequently used to rapidly find offset guide stars. Observer access is normally limited to guide star selection. A Sun SPARCstation 20/71 (wekiu) with color monitor, 1.0 and 4.0 Gbyte disk drives, and 96 Mbyte of memory. The operating system is Unix (SunOS 4.1.4), and windowing systems are X11R6 and OpenWindows. Standard analysis packages such as IRAF and IDL are available. This workstation is normally used by the observer at the 2.2-m telescope. QUIRC and KSPEC and some of the CCDs are run directly from it. It is also used for quick-look analysis of data, as well as to store the night's data from the instrument being used. A Sun SPARCstation 2 (halley) with color monitor, 0.4, 4.0, and 1.5 Gbyte disks, 64 Mbyte of memory, and exabyte tape drive. The operating system is Unix (SunOS 4.1.4), windowing systems are X11R6 and OpenWindows, and standard analysis packages include IRAF and IDL; it is setup in a similar manner to the workstations at the IfA. This workstation is normally used by the observer at the 61-cm telescope. It is normally located in the 2.2-m telescope computer room. When QUIRC is used at the 61-cm telescope, halley is used to control it; QUIRC can be run remotely over the fiber-optic cable which connects the 61-cm telescope with the 2.2-m telescope. When halley is not in use at the 61-cm telescope, it may be used by the observer at the 2.2-meter telescope. Two NeXTstations (anaconda and cobra), each with 32 Mbyte of memory, and an external disk drive, for control and data acquisition from CCD detectors. A NeXTstation viper for control of the offset guider and for tip-tilt guiding. A Sun SPARCstation 10/41 (baade), located in the UH computer room at Hale Pohaku, with color monitor, 0.4, 1.6, and 3 x 2.0 Gbyte disk drives, CD-ROM drive, exabyte tape drive, and 96 Mbyte of memory. This computer is our most powerful workstation at Hale Pohaku, and is setup in a similar manner to wekiu and halley. It is used as the principal data storage and data archiving computer, and for detailed examination of data during the daytime. A Sun SPARCstation IPX (kepler), located in the 2.2-m telescope office at Hale Pohaku, with color monitor, 0.4 and 1.0 Gbyte disk drive, and 48 Mbyte of memory. This is intended to be used principally as an X-terminal to baade, which has most of the disk drives and peripherals. The only form of data archiving presently supported is exabyte tapes. These tape drives use 8mm video cassettes, and a 120 min tape can hold approximately 2.3 Gbyte of data. Tapes are not supplied to observers - observers should bring an adequate supply of tapes with them. We recommend the use of data grade 8mm tapes. Their cost is in the range $8-10 each, depending on brand, quantity purchased, and source. Examples of tapes which we know work well are Sony and Exabyte data cartridges. Recent changes in the manufacturing process for the Sony MP tape (which we previously recommended) have caused unacceptable failure rates with these cheaper tapes, and we recommend that they are not used. We strongly recommend that observers make at least two exabyte data tapes of all data, in case of problems with a tape. Data may be written onto more durable, and more reliable CD-ROM media in Manoa after the observing run. CD recordable disks presently cost approximately $8 each, and hold approximately 650 Mb on a 74 minute disk. 4.2 Mechanical Shop A small mechanical shop in the 2.2-m building contains a band saw, vice, drill press, grinder, lathe, and an assortment of hand tools. This equipment is not suitable for instrument fabrication and is for emergency repairs only. Visiting observers should bring their own tools. 4.3 Electronics Shop A small electronics shop in the 2.2-m building is used for servicing the telescopes, instruments and control equipment, and contains a modest assortment of wire, miscellaneous electronic components, soldering irons, and simple test equipment. Visiting observers should not rely on this facility, except to provide possible emergency back-up if they experience simple difficulties with their own equipment. Visiting observers should bring their own supply of spare parts and test equipment. 4.4 CCD/IR Dewar Lab A small, 200 ft^2, unheated area with work bench and cabinet space is available on the ground floor of the 2.2-m building. A turbo pump is located in this room, along with a modest selection of ordinary hand tools, which are available for repair, adjustment, and testing of instruments. 4.5 Power at the Summit Electrical power at the summit is now provided by the Hawaiian Electric Company (HELCO) transmission grid. Voltages available are 480 V, 277 V, 208 V, and 120 V in a three-phase, four-wire, 60 Hz distribution system. Regulated 110 V from wall sockets is also available. Two small Uninterruptible Power Supplies (UPS) provide power to the 2.2-m telescope control computer, data acquisition and instrument control computers, and instruments, in the event of short power outages, and a small generator provides power for closing the 2.2-m telescope dome in the event of a complete outage. 4.6 Living Facilities in the 2.2-m Building A heated room in the 2.2-m building is provided with comfortable furniture, a cot and a kitchenette. This facility is for use by astronomers and assistants for short rest periods during the day or night. A stock of several days' food is maintained at the summit - this is for emergency use only, in case observers or staff are trapped at the summit by sudden, severe weather (heavy snow can close the road for many days). The emergency food is stored in a storage room adjacent to the day room, on the ground floor of the 2.2-m telescope building. 4.7 Loaned Facilities On special occasions, certain instruments or apparatus may be loaned to visiting observers who have experienced difficulty with their own equipment. Visitors should not, however, rely on the availability of any apparatus on loan unless prior explicit arrangements have been made in writing with the Director. This applies, for example, to such items as vacuum pumps, oscilloscopes, amplifiers, cryogenic transfer tubes, etc. Chapter 5 SUPPLIES 5.1 Dry Ice Solid C02 snow can be made at the Observatory in small quantities (several ounces) by rapid expansion from bottles of compressed gas; bottled C02 is normally available for modest demands. Larger quantities of dry ice can be obtained in Hilo, but this requires advance notice of several days. For quantities over 2 kg, requirements should be indicated on the "Visiting Observer Information Sheet". 5.2 Liquid Nitrogen and Liquid Helium The purchase and handling of these cryogens is supervised from Hilo (see Appendices for person to contact). Visiting observers requiring modest amounts of LN2 (25-160 liters) for a single observing run are requested to coordinate their needs through the UH Telescope Superintendent on the "Visiting Observer Information Sheet". There are presently no facility instruments which use liquid helium; liquid helium is now only rarely used, and only with visitor instruments. Requests for LHe must reach Hilo by telephone or in writing a minimum of 4 weeks before the day they are needed. It is most economical to purchase LHe in 30, 60 or 100 liter dewars, and the LN2 in 160 liter dewars owned by UH. Visiting observers using cryogens will be billed following their observing run for the amounts they ordered or used, whichever is greater. Liquid nitrogen is produced in Honolulu and shipped by barge to Hilo, where it is transported to the summit by UH personnel. On reaching the summit, a 160 liter dewar shipped full from Honolulu normally contains 150 liters. LHe is air shipped from Honolulu by Gaspro and is distributed by Gaspro, Inc., in Hilo. Users should consider the loss factor when estimating their needs. The current approximate costs of LN2 and LHe delivered to the summit are listed in Appendix G. The freight address of the institute for Astronomy in Hilo (listed in Appendix A) should be used for shipments of cryogens ordered by individuals. 5.3 Pumping and Transfer Tube Information The rubber hose used for pumping liquid helium in the infrared detector dewars is about 2.5 cm (1 in) in inside diameter and 4.9 m (16 ft) in length. The transfer tube diameter is 6.4 mm (0.25 in) on the delivery side, with a smaller tube diameter of 3.3 mm (0.13 in), and length of 3.8 cm (1.5 in) on the end. The mechanical pump is a Welch pump, with a capacity capable of pumping most LHe dewars. A turbo pump is available for pumping the vacuum casing of dewars. Chapter 6 TELESCOPES Visitors requiring specific information about the optical or mechanical configuration of the telescopes should communicate with the Support Scientists of the UH Telescope Superintendent in Hilo. 6.1 61-cm (24-inch) Telescope This telescope, made by Boller and Chivens and furnished to the University by the US Air Force, is located in a small dome 150 m southwest of the 2.2-m dome, below UKIRT. It is used mainly for wide-field imaging and photometry. The Cassegrain focal lengths are 9,240 nun (f/15.2) and 36,500 mm (f/60), providing scales of 22.3 and 5.65 arcsec/mm. An f/35 chopping secondary is also available for infrared work. The telescope is used almost exclusively with the f/15.2 secondary mirror. No one presently at the University has any experience with the f/60 secondary mirror. The telescope is capable of variable tracking rates in both Right Ascension and Declination. The telescope can be pointed manually, by reference to setting circles which are accurate to about 1 arcmin in each axis. A computerized control system (using a 486-PC) for this telescope has been installed, and is still undergoing testing. Since May 1996, we have been able to control this telescope remotely and robotically. Work is still underway to make this remote operation safer and more robust. Fiber-optic cables link this telescope to the 2.2-m telescope dome, providing a fiber ethernet connection, fibers for instrument control, and a fiber for a video camera to remotely view the status of the telescope. This telescope is not generally available for use by visiting observers. The layout of the instrument mounting flange of the 61-cm telescope is shown in Fig6_1 An offset guider (with eyepiece), which has a mirror which can be moved on axis for object acquisition, is commonly mounted onto the telescope. Instruments such as QUIRC and the filter wheel/CCD normally mount onto this guider. The guider is 8? inches thick, meaning that most instruments mounted onto it have their focal planes close to the nominal focal plane, located 12 inches behind the instrument rotator. A 25-cm telescope (Ritchey-Chretien f/10) can be mounted on the counterweight side of the polar axis of the 61-cm telescope. This 25-cm telescope can only be used with the 1024 x 1024 near-infrared camera (QUIRC). The 25-cm telescope mounts on top of QUIRC, and QUIRC is mounted to the 61-cm telescope. The combination of 25-cm telescope and QUIRC is referred to as QUIST (QUick Infrared Survey Telescope). QUIST has a field of view of 29'x 29' with pixels of 1.70". QUIST is still in experimental use, and we request that astronomers consult with support staff before submitting a proposal to use this instrument. 6.2 2.2-m (88-inch) Reflector The fused silica primary has a diameter of 2.24 m (88.13 in), an unvignetted diameter of 2.22 m (87.5 in), an edge thickness of 291 mm (11.47 in), and weighs 2.17 tons (4780 lb). The hole in the center of the primary mirror has a diameter of 24.13 in (613 mm). The nominal f/10.14 Cassegrain (Ritchey-Chretien) focus has a focal length of 22.50 m (886 in), an unvignetted field of 46 arcmin, and a field image scale of 9.17 arcsec mm (109 m arcsec ). Nominal (RC) focus is 311 mm (12.25 in) behind the mirror cell, or 111 mm below the bottom surface of the instrument adapter/offset guider used for most Cassegrain instrumentation (see Section 7.2). Maximum telescope focus range at f/10 is from the back of the mirror cell to 68.5 cm (27 in) behind it, but the focus range of the offset guider TV is presently only 30 mm around the nominal Table 6.1: 2.2-m primary and secondary mirror dimensions and curvatures ____________________________________________________________________________ | Primary | f/10 | f/33.8 | f/31 Diameter | 2.239 m | 0.660m | 0.610 m | 0.211 m Thickness | 0.291 m | 0.102m | 0.102 m | Radius of curvature | 12.3445 m | 4.19819m | 3.32105 m | 1.2936 m Conic constant | 1.0535 | 3.604 | | 2.173 ____________________________________________________________________________ focal plane. The nominal separation between the primary and secondary mirrors is 183 in (4.65 m). The 5 mirror f/33.8 coude focus has a focal length of 75.20 m (2,961 in), a useful field of 3.5 arcmin, and an image scale of 2.7 arcsec mm (367 m arcsec ). The coude focus is located in an enclosed slit room (see section 6.2.4). The Cassegrain and coude optical trains can be interchanged in about 30 min during the night, if necessary, for special programs. These two foci share the same focus drive which moves within the encoder range 91-17553. Each step (of 27 m) represents movement of the f/10 Cassegrain focal plane by 39 m (0.00154 in), or of the f/34 coude focal plane by 426 m (0.0168 in), with increasing number indicating movement of the f/10 secondary towards the primary (and of the f/34 secondary away from the primary). Focusing should normally be determined to 10 units (or better) to restrict focusing blur to less than 0.3 arcsec. With the CCD, focusing is usually done by taking a "focus plate" (a sequence of images at different focus settings). A video rate CCD readout is expected to be available soon, which will make it easier to focus the telescope on bright stars. The Cassegrain f/31 secondary has been optimally figured to match the shape of the primary mirror, and has an enclosed energy of 80% within 0.2 arcsec. The secondary mirror is mounted to the spiders and top-end ring via a hexapod mount, which allows 6 degrees of freedom of movement, so that collimation, tilt, and focus adjustments can be made remotely. The mirror is attached to the hexapod mount via a piezo-electrically driven platform that is used for tip-tilt correction. The tip-tilt correction is easy to use and is available to all observers who use the f/31 secondary mirror. A top-end change is required to use the f/31 secondary mirror. With this mirror, the telescope has a nominal focal length of 68.78 m (2707 in), producing an image scale of 3.00 arcsec/mm (333 micron/arcsec). Exact focal length depends upon exactly where the instrument focal plane is located relative to the mirror cell. Basic specifications (where known) for the mirrors at the 2.2-meter telescope are listed in Table 6. 1. Additional details, including figuring errors, may be found in Table 7.2. There is no infrared chopping secondary mirror. The old f/35 chopping secondary has been replaced by the fixed f/31 secondary mirror, and is no longer available. Instruments which work in the thermal infrared (beyond 2.5 m) and require chopping therefore can no longer be used on the 2.2-m telescope. The InSb photometer and Ge Bolometer, which until 1990 were used with the chopping secondary mirror, have been decomissioned, and are not available. The 2.2-m telescope also has two bent Cassegrain foci, which can be used with either the f/10 or the f/31 secondary mirrors, together with the coude tertiary mirror (which is mounted in the sky baffle attached to the center of the primary, and rotates with the instrument rotator). The tertiary mirror can be moved in and out of the beam remotely, and reflects light to the coude system at instrument rotator position 270, to the south bent Cassegrain focus at rotator position 180, and to the north bent Cassegrain focus at rotator position 0. These additional foci are used for special purpose instrumentation, and are not available for visitors' equipment. Telescope track rates up to 99 arcsec/s away from nominal are possible in either Right Ascension or Declination, and can be set to 0.0001 arcsec/s. To facilitate balancing the telescope, visiting observers who mount their own equipment at the Cassegrain focus should know the weight of their instrument, including the weight of dry ice, cryogens, hanging cables, and the position of the center of gravity. Observers who dismount equipment (such as dewars) during their run should supply a dummy balancing weight. Electronics to be mounted on the telescope should preferably be made to fit inside standard 19-inch racks. The layout of the telescope and dome are illustrated in Fig6_.2 and Fig6_3, the layout of the 2.2-m Cassegrain instrument mounting flange is shown in Fig6_4, and the layout of the 2.2-m bent Cassegrain instrument mounting flange is shown in Fig6_5. Note that instruments are normally not mounted directly onto the Cassegrain mounting flange. Instead, they are mounted onto the offset guider, which is described in Section 7.2, and its bolt circle is described in Section 7.2.3. There is presently no ability to guide at the bent Cassegrain focus; this focus is not normally used. 6.2.1 Telescope Control System The 2.2-m telescope positioning, tracking and slewing are controlled by an LSI-11/23 computer programmed in FORTH. The computer itself is not part of any feedback loops, but merely sets hardware values according to requirements. The computer pointing model includes corrections for atmospheric refraction and telescope flexure. Pointing (slewing) is accurate to 10 arcsec RMS over the whole sky, with offsets up to a few arcmin accurate to 2 arcsec. Unguided tracking is generally good to several arcsec/hr, but the telescope is normally autoguided using the TV system. A facility for guiding at non-sidereal rates is now available for observations of solar-system objects. Telescope position control operates via a conventional phase-lock loop using up/down counters to determine position error. When the telescope is tracking, the computer increments these counters, while incremental encoders on the telescope drives detect telescope motion and decrement the counters. Each count represents 0.05 arcsec on each drive axis, and an inner feedback loop operating at about 10 Hz sends signals to drive the telescope at a velocity proportional to the number of counts (position error). The gain is set high so that one or two counts will drive the telescope at normal track rates with negligible error. The desired track rate on both axes can be set and adjusted in real time by thumbwheel switches on the control panel, which the computer reads. The maximum track rates are within 99 arcsec/s of sidereal, for solar system objects, with resolution to 0.0001 arcsec s (1). Slewing is achieved by applying a relatively large input directly to the velocity control loop. Absolute position is also measured with incremental encoders with resolution of 1/16 arcsec on both axes. These encoders and the TCS are energized through the Uninterruptible Power Supply so that positional information is maintained throughout short power outages. If the absolute position is lost, however, the system must be reinitialized by setting the telescope accurately to the zenith with two precision bubble levels, and loading the proper numbers into the counters. Communication between instrument computers and the TCS is now in common use. This is achieved via a communication daemon, running on tycho. Commands and protocol are similar to the system at the IRTF. Further details can be obtained from support staff if required. 6.2.2 Cassegrain Observing Platform A platform which can be raised and swiveled hydraulically provides access to instrumentation at the Cassegrain focus of the 2.2-m telescope. Permanently located on the platform is a mobile electronics rack which houses a panel for platform control (up, down, left, right), and a monitor for telescope guiding which is done via a handset attached directly to the telescope. Some space remains on the platform for additional equipment and, when required, an additional electronics rack or small table can be accommodated. Cables from equipment at the Cassegrain focus to the platform should be at least 8 m (25 ft) long to permit stowing the telescope in the horizontal position when the platform is down. Left and right motions of the platform should be used only with simultaneous up or down motions, and extreme care must be taken to avoid hitting the yoke counterweight tube whenever the telescope is away from the zenith. 6.2.3 Control Room Especially large or temperature-sensitive components should be placed in the heated Control Room, or alternatively in the Control Support Room below, and connected by cable to the equipment at either the Cassegrain or coude focus. Communication between the focus position and the Control or Control Support Rooms is by microphone. Visiting observers wishing to locate equipment in the Control Room must indicate their plans on the "Visiting Observer Information Sheet". Minimum cable length from the Cassegrain focus to the Control Room is about 18 m (60 ft), and to the Control Support Room, about 26 m (85 ft). Fifteen unused coaxial cables are strung from the Cassegrain focus through the telescope to the Control Support Room. They are about 46 m (150 ft) long. 6.2.4 Coude Focus The coude focus is reached by flipping the f/10-f/34 top-end ring (manually), and by inserting the tertiary mirror (remotely) with the rotator set to 270 . Mirrors 4 and 5 are permanently mounted, and this changeover can be achieved in about 30 min for special applications. The coude focus travel limits are from approximately 2.5 m (8 ft) ahead of the slit to approximately 5.5 m (18 ft) behind the slit. The polar axis terminates in an instrument mounting flange containing four 3/8 in, 24 tapped holes equally spaced on an 11 in. diameter bolt circle. The slit position angle is given by the following equation: PA HA Dec + 36 (6.1) The normal focus encoder position is approximately 12050. 6.2.5 Fiber-optic Audio-Video link A fiber-optic audio video link has been installed between the 2.2-m telescope and Hale Pohaku. Diagrams showing this are in Fig6_6 and Fig6_7. We presently have three cameras at the summit. One of these will be installed to look outside, another will be installed in the dome, and the third is installed in the control room. The outside and dome cameras are black-and-white cameras, and work well in low light levels. The camera in the control room is a color camera. There are three microphones in the control room-one for the observer, one for the operator, and a lavalier microphone which can be clipped onto your shirt for hands-free use (when using this microphone, take care-you need to remove it when you leave the control room!). A color monitor in the control room shows the video image coming from Hale Pohaku, and an amplifier and speakers allow you to hear the person at Hale Pohaku. At Hale Pohaku, a microphone, color camera, color monitor, and amplifier and speakers are all located in the 2.2-meter telescope office. This link provides high-quality two-way audio-video communication between the summit and Hale Pohaku. At the summit, an audio-video switcher allows selection of different cameras and other video and audio sources. The switcher may be operated manually, or can be operated remotely using the program videoi on tycho. We intend to connect the summit VCR to this system to permit remote diagnosis of problems via this link. We are presently exploring a lower-bandwidth extension of this link back to Manoa via the existing T-1 computer link. Chapter 7 INSTRUMENTATION 7.1 UH Telescope imaging scales and field sizes Table 7.1 shows the imaging scales, pixel and field sizes for UH optical CCDs and infrared detectors (QUIRC) in a number of possible configurations on various telescopes on Mauna Kea. Table 7. 1: Imaging scales and field sizes ___________________________________________________________________________ | Orbit 2048 | Tek 2048 | QUIRC Telescope|Focus|Scale | pixel field | pixel field | pixel field (arc |(arcsec)(arcmin)|(arcsec)(arcmin)|(arcsec) (arcmin) sec | | | mm) | | | ______________________|________________|________________|__________________ 25cm |f/10 | 83 | | | 1.7 29 61cm |f/15 | 22.7 | 0.34 11.6 | 0.55 18.6 | 0.462 7.88 |f/35 | 9.75 | 0.15 5.0 | 0.23 7.99 | 0.198 3.39 2.2m |f/10 | 9.17 | 0.14 4.7 | 0.22 7.51 | 0.187 3.18 |f/6.4| 14.3 | 0.21 6: | 0.34 6: | - - (Z135 mm)(1) |f/31 | 3.0 | 0.045 1.54 | 0.072 2.46 | 0.061 1.04 CFHT |f/8 | 7.17 | 0.11 3.67 | 0.17 5.87 | 0.146 2.50 |f/35 | 1.71 | - - | - - | 0.035 0.59 IRTF |f/35 | 1.95 | 0.029 1.00 | 0.047 1.6 | 0.040 0.68 Notes: (1) The Zeiss 135mm lens is assumed to be used in conjunction with the Wide Field Grism Spectrograph (WFGS) as a focal reducer/ spectrograph. Note that the field of view will be defined by vignetting of the focal reducer, and is approximately 6 arcmin. 7.2 2.2-m Cassegrain guider and instrument mount 7.2.1 Instrument Rotator The Cassegrain focus is provided with a (manually operated) instrument rotator which is capable of supporting 230 kg (500 lb) with a maximum moment of 170 kg in (1200 ft lb). Fig7_1 shows the new slide-mounted 19-inch electronic rack system, which is adjusted by the crew to provide balance for different instrument configurations. The rotator, racks and guider can normally be rotated by 100 degrees from the default orientation (270 degrees) to permit orientation of a spectrograph slit at any position angle, or of the guide probe dichroic to access guide stars without blocking the science beam. Cassegrain rotation requires careful two-person operation with the telescope at zenith, to avoid stretching cables, and takes about 15 minutes. The nominal f/10 Ritchey-Chretien focus lies 111 mm below the guider instrument mount surface. At f/10, instrument foci more than 50 mm below this will result in slight off-axis coma. The nominal f/31 focus is equivalently placed, but has considerably more focus latitude. 7.2.2 CCD guider A new CCD guider was installed in 1994 to replace the older ISIT TV system. It accesses guide stars over almost all the Cassegrain field, works to fainter limiting magnitudes, and provides both telescope guide signals (f/10 and f/31) and fast guide signals to the f/31 tip-tilt secondary (see below). Figure 7.1 illustrates the layout of the guider X-Y stage, pick-off probe and guide CCD camera. In this illustration, the guider is shown with the science instrument removed, and with the pick-off probe on-axis (in a typical configuration for on-axis tip-tilt guiding at f/31). Operation of the guide X-Y probe and CCD camera focus is controlled by the program Atlas running on a NeXT computer viper in the control room. Operation of either the telescope guider at f/10 (program MiniOtto), or telescope and fast-secondary guider at f/31 (program Otto) is controlled by the same NeXT (viper). Graphic visualization of the Cassegrain guider environment and some guide probe functionality is integrated into the telescope user interface program tesi (see below) which runs on a Sun computer (tycho) in the control room. The guide probe moves over a 47 x 40 arcmin field at f/10 (approximately 16 x 13 arcmin at f/31), and can access guide stars anywhere in that field. The guide probe currently consists of a 75 mm diameter dichroic (6.35 turn thick), oriented at an angle of 45 to the optical axis. The dichroic transmits wavelengths longer than 720nm, and reflects light with wavelength shorter than 720nm. The reflected light is focused on a Tektronix 512 x 512 CCD, which is perpendicular to the science beam and parfocal with the science instrument. This arrangement permits both off-axis guiding in any configuration, and on-axis guiding with an infrared science instrument (the science beam is shifted slightly, and the telescope focus lowered by insertion of the dichroic). Guide CCD focus travel currently extends from 4 mm above nominal focus to 26 mm. below. For f/31 instruments with a low focus, a 75 mm focal length converging lens can be inserted before the guide CCD to change the focus range to 12-150 mm below nominal. Insertion of the lens changes the pixel scale on the guide camera (varies with instrument focus depth), but does not change the scale of the probe movement on the sky. Lenses with focal lengths of 100mm (range 8-67mm) and 150 mm (range 5-32 mm) are also available. The longer focal length lenses vary the pixel scale on the guide camera to a lesser degree. Guide star acquisition consists of a short full-frame guide CCD exposure to identify the guide star position. The star is then marked by the operator, and the probe or telescope position adjusted to place the starlight accurately on a small, predefined subframe or quad-cell. The subframe typically consists of a 5 x 2 readout area, each consisting of 15 x 15 physical CCD pixels (each 27 m square). The first 2 x 2 subpixels are discarded because of readout noise, the next 1 x 2 subpixels form the bias area to one side of the star, and the last 2 x 2 sub-pixels form the quad-cell itself (7.4 x 7.4 arcsec at f/10, 2.4 x 2.4 arcsec at f/31). Guiding consists of reading this subarea subtracting bias from the 4 quad-cell signals, computing the centroid in 2 directions, and using these signals to guide the telescope and tip-tilt mirror when in use. The quad-cell area is typically in the center of the CCD for f/10 guiding, but very close to the readout corner for added speed during fast guiding (for tip-tilt guiding, readout is typically 20 - 100 Hz). Guiding at f/10 consists of sending slow guide signals (1-2 Hz) to the telescope, which ensures accurate tracking and removal of some telescope vibration. Guiding at sidereal and non-sidereal rates is possible. Guiding at f/31 consists of sending fast guide signals to the f/31 tip-tilt secondary, which has an operational range of 5 arcsec, and slow guide signals to the telescope when the tip-tilt secondary is significantly displaced from its central position. The speed of the fast guide loop is determined by the guide star exposure time, which typically varies from 200ms (13mag) to 5ms (9mag), corresponding to 4-150 Hz after readout overhead. Fast guiding will remove telescope vibration and some atmospheric image motion. Best results are obtained with a bright, on-axis guide star. Diffraction limited images at K (FWHM=0.25") have been obtained in long exposures, and images with FWHM=0.20" have been obtained in the H-passband. Significant image improvement is usually obtained with fainter guide stars and guiding 2-5 arcmin off-axis. More information on the new autoguider may be found at: http://ccd.ifa.hawaii.edu/docs/auto.htm1 7.2.3 Instrument mount bolt circle The new instrument mount consists of 3/8-16 tapped holes at regular 30 degree intervals on a 20-inch bolt circle. 7.3 tcsi-user object selection interface 7.3.1 Telescope Control System Interface-tcsi tcsi is an X-window, event-driven interface program which provides communication between the user and/or Telescope Operator (TO), the 2.2-m Telescope Control System (TCS) and the new offset guider (Atlas). Users can select objects and stars, find appropriate photometric standard stars, and send slew requests for them to the TCS. Users can also schematically display their object fields and available guide stars (GS), select a GS and send the ATLAS guide probe to it (before or while the telescope is slewing). Prospective users can create or edit their object-list and display the output from tcsi on their own workstation prior to their run. Users can pre-examine object/GS fields, preselect standards and plan spectrograph rotator angles, for example. Slew and Atlas requests are disabled when tcsi is operated remotely. Please note that we prefer users to keep their object lists on halley rather than tycho which is the Telescope Operator's workstation. The fields are named in columns 1-12, RA as hh mm ss.s after column 13, Dec as dd mm ss.s, Equinox as yyyyy, followed by comments, which are ignored. The name field can exceed 12 cols if there are no embedded spaces past the 11th column; coordinates can be separated by spaces, commas, colons or tabs (which can cause uneven presentation), and the +sign is optional for northern declinations. The default equinox is 1950.0, and the maximum number of objects is 500. Examples of the tcsi window and of the sm Cassegrain field graphics (at f/10 and f/31) are shown in Fig7_2, Fig7_3 and Fig7_4. 7.3.2 Starting tcsi tcsi runs on the 2.2-m control workstation tycho, which also stores all the catalog information. It can be run also from wekiu in the 2.2-m control room (slew and Atlas requests permitted), or from a workstation at Hale Pohaku or Manoa running X11 (slew and Atlas commands disabled). Invoke the program by typing: xhost tycho in your workstation console window, then r1ogin tycho -1 obs Password: (available from TO or Richard Wainscoat in Manoa) setenv DISPLAY :O.O tcsi objectlist &(use your own file objectlist on tycho), or one of the files in that directory to try it out). This will open the main tcsi window on your X-workstation. The window has four main sections and an optional sm display window (examples are shown in Figures 7.2, 7.3, and 7.4). 7.3.3 tcsi windows 1. The buttons near the top control the user's file; a subwindow below shows the contents of the file. The user's file name is shown in the top panel, and a new file can be selected by editing the Object File name domain, then pressing the New File button. An object is selected by clicking the mouse-cursor in the user file subwindow; long files can be scrolled with the slider bar to the right. Note that objects and/or coordinates needed quickly can be simply typed into the object sub- window directly, but will vanish when the process quits unless the file is saved. It is preferable to add extra objects by editing the user file, and pressing New File. A SLEW request to the selected object is generated (from privileged workstations) by pressing Get Object. The telescope will not slew until the request is approved by the Telescope Operator. 2. The second section contains buttons for finding stars near to objects or the current telescope position. Stars from the SAO, BSC, GSC or photometric standard (optical and infrared, bright or faint for each) catalogs can be selected by pressing the left mouse button on the appropriate button. For the selected catalog, Object Star finds the 8 stars nearest to the selected object, Local Star finds the 8 stars nearest to the current telescope position. Select a star by clicking the mouse-cursor on a star in the star subwindow. Entering a close match (number or name) to a known star in the Star: field and pressing Named Star will search the database(s) for that star, and display the star (automatically selected) and 7 near neighbors if it is found. The display format includes name, coords, epoch, magnitude and angular distance from object, star or position in degrees. Standard display includes V and V-I for optical or K and J-K for infrared standards. Guide star display includes positional error (in arcsec)/number of measurements, but this is optimistic for bright guide stars. GSC refers to the HST Guide Star Catalog (which is read from CD-ROM). The bright optical standards are from Landolt, AJ, 88, 439 (1983), and the faint optical standards are from Landolt, AJ, 104, 340 (1992). The bright infrared standards are from Elias et al., AJ, 87, 1029 (1982), and the faint infrared standards are from the unpublished UKIRT list. Get Star generates a SLEW request for the selected star, if permitted. 3. The third section contains telescope and guider configuration buttons, guide star (GS) selection buttons and a subwindow which shows the 8 brightest guide stars. Object GS finds the 8 Guide Stars nearest to the selected object. Star GS finds the 8 Guide Stars nearest to the selected star. Local GS finds the 8 Guide Stars nearest to the current telescope position, but this will include telescope pointing errors, so it is preferable to use Object GS or Star GS where possible. The display format is name, Atlas X-Y position, magnitude, positional error in arcsec/number of measurements. Note however that Guide Stars brighter than 10 are quite likely to have positional errors 1 arcsec due to photographic plate saturation. Use bright stars for simple mosaic/dithers, use SAO or faint Guide Stars for accurate positions. The guider magnitude limits are approximately 8 at the bright end (guider CCD exposure 5-10 millisec, 80-120 Hz frame-rate with good S/N but avoiding saturation) to 15 at the faint end (200-250 millisec exposure, 4-5 Hz frame rate, with adequate S/N). The guider display background color changes from black (OK, star background 3000 DN/frame), to green (warning, 1500 DN 3000), to yellow (failure, DN 1500, no guide signals transmitted). If the signal is too faint, increase the exposure (decrease the frame rate) or find another guide star. The default configuration is f/10 focus and Tek 2048 detector; selecting f/31 focus changes the scale appropriately and selecting another detector changes the size of the science field, which affects the limits to the probe position. The optional spectrograph buttons (WFGC or FOS at f/ 10, HARIS or KSPEC at f/31) only affect how the Spectrograph Slit Position Angle (SlitPA, measured East from North on the sky) varies with the Cassegrain Rotator setting (CassRot, default 270). When doing spectroscopy, a desired PA can be entered in SlitPA. The Cassegrain Rotator setting necessary to achieve this PA will then be displayed in SetRot (which includes a small zero point error). This will also update the new rotator setting in CassRot. However to actually achieve this, the telescope should be slewed to the Zenith, the observer should go up on the platform with the TO, release the T-bar clamp (towards the visitor gallery when at 270 ), rotate slowly to the desired angle (checking all cables are free) and reclamp. Note that the rotator is designed to allow 100 from the default 270 position, which permits all slit PAs. 4. The lowest section displays warnings, informational messages, and monitors the communications between tycho and the TCS. It is advisable to pay some attention to this window and, if there is unusual output there after sending an object's coordinates to the TCS, it is best to resend them. 5. An optional sm window is generated by clicking the sm button in the third (configuration) panel, and placing the new sm window somewhere convenient on the desktop. When the GS buttons are activated, a schematic presentation of the 2.2-m Cassegrain field (large circle), guider (horseshoe-shaped area) and detector field-of-view (central square) will appear here, arranged to match the focus, detector and Cassegrain rotation selected. The readout corner of the selected detector is marked with a small circle. Available guide stars will also be drawn in the sm window, where brighter stars are drawn larger, and filled symbols represent stars accessible to the Atlas probe. The user/TO can visually select a guide star and determine its identity by clicking ID, then clicking the sm cursor on the selected GS; this will identify the selected GS in the star sub-window, and in the GS subwindow if the guider can access it. From selected workstations, the user/TO can also direct the Atlas probe to a selected GS by clicking XY then clicking the sm cursor on a selected guide star. For on-axis guiding with an infrared science instrument it is advisable to select Dichroic ON to also display the probe, guider CCD and dichroic position with respect to the science field. Guide stars should be selected so that the dichroic either completely covers, or completely avoids the science field. The readout comer of the guider CCD is also marked with a small circle. Users should note that insertion of the dichroic lowers the telescope focus on the science detector (reduce f/10 focus by 7; reduce f/31 focus by 25 when inserting the dichroic). 7.4 f/10 secondary The 2.2-m telescope was designed as a Ritchey-Chretien wide-field telescope with a 45 arcmin coma-free field at the nominal f/10.14 Cassegrain focus. This wide-field capability is one of the strengths of the telescope, particularly in an era of large optical and infrared arrays and mosaics, and provides a valuable wide-field complement to the large telescopes now on Mauna Kea. The f/10 secondary delivers 80% energy (080) within 0.4 arcsec over the full 45-arcmin field (approximately 300mm diameter at 9.17 arcsec/mm), but the curved focal plane requires a field flattener for imaging arrays larger than 100 mm in size. The f/10 focus motor moves the mirror in encoder steps of 2.9 m, resulting in movement of the f/10 Cassegrain focal plane by 39 m, with increasing number indicating movement of the f/10 focal plane towards the primary. 7.5 f/31 secondary The old f/35 infrared chopping secondary suffered from significant astigmatism and poor image quality, which rendered it useless for imaging work with the new generation of infrared arrays. Site testing in the 1980s had indicated that the best intrinsic seeing on Mauna Kea (0.2-0.5 arcsec FWHM) was being degraded by existing telescope image profiles which were typically 0.5 arcsec. These were produced by a combination of dome seeing, optics, optical misalignment with telescope position, and mechanical vibration. Dome seeing and alignment problems can be addressed by careful calibration and thermal management. The mechanical vibration intrinsic to an older telescope like the 2.2-m can only be addressed by incorporating a low inertia component which can be guided faster than the telescope resonant frequency (0.5-2 Hz)-a tip-tilt secondary. Additional seeing improvements possible from Adaptive Optics (AO) depend on the ratio of telescope diameter to the Fried seeing cell size (which in turn increases with wavelength). The ratio is typically large for large telescopes, even at longer wavelengths, requiring high order adaptive systems for significant improvements. However since it is small for the 2.2-m telescope, the simplest (tip-tilt) adaptive optics system can deliver 70% of the gain possible with AO, provided that the static optical quality is maintained. In 1989 it was decided to build a new high resolution secondary mirror for the 2.2-m telescope, to complement the existing wide-field f/10 capability, with the following characteristics: high optical quality to match the best seeing available on Mauna Kea (0.2-0.5 arcsec FWHM typically); small enough to permit fast tip-tilt guiding, but large (fast) enough to permit a reasonably large, coma-free field ( 4 arcmin); remote collimation and focus with a hexapod mount to maintain optical alignment; concentrate on the 'extended optical' wavelength regime (0.3-2.3 m), which corresponds to our main detector sensitivities (CCD and HgCdTe infrared arrays), and avoids the severe extra mechanical constraints required when chopping for thermal infrared background subtraction. Extra-focal measurements of the 2.2-m primary were made in 1989 to accurately determine its surface figure. The measured conic constant was significantly different from the original manufacturer's figure, but these results (Table 7.2) indicated an excellent surface which could deliver theta(80)=0.2 arcsec with a secondary figured to remove the spherical aberration of the primary. The choice of focus is a compromise between longer focus (small, lightweight secondary which is easier to tip-tilt) and shorter focus to minimize the off-axis coma. The compromise choice was a quartz f/31 secondary, specified to match our measured primary. This mirror was ordered from Optical Science Center (Tucson) and delivered in 1991. The f/31 secondary is slightly undersized (it illuminates 2.1-m of the primary), has a diameter of 211 mm and weighs 1.8 kg. The f/31 focus has coma which increases linearly with distance off-axis; at a distance of 2 arcmin off-axis, the coma amounts to 0.35 arcsec. The image scale is 3.0 arcsec/mm. 7.5.1 f/31 hexapod and Physik Instrumente tip-tilt platform The f/31 high resolution Cassegrain focus is much more demanding (by a factor of 10 compared to the f/10 focus) in its requirements of primary-to-secondary separation, centering and alignment. Ideally it requires active control of both primary and secondary to compensate for telescope flexure across the sky. A hexapod support system for the f/31 secondary was built at the IfA, and installed on the 2.2-m in 1993. The older f/35 top-end ring was retained, but the spider support mechanism, hub and hexapod positioner were all redesigned and built at the IfA, and installed in 1993. The optics and solar groups at the IfA had successfully used a number of small tip-tilt platforms from Physik Instrumente (PI). Their experience led directly to the concept of a piezo-driven tip-tilt platform which was large enough to support and Table 7.2: 2.2-m primary and f/31 secondary mirror optical specifications ______________________________________________________________________ Primary f/31 secondary Notes ______________________________________________________________________ Diameter 2.2 m 211 mm Radius of curvature 12344.5 mm 1293.6 mm Manuf. conic const. 1.0497 2.173 Measured conic const. 1.0535 RMS surface error 40 nm 17 nm MAX surface error 120 nm 130 nm Sph. Aberration 11 m 20 nm f/31 combination of 2 mirrors Astigmatism 250 nm 150 nm largest remaining error Coma 150 nm 60 nm Triangular 220 nm reduced to 60 nm with new air-regulator Wavefront error 300 nm twice NTT, slightly less tahn CFHT ________________________________________________________________________ Table 7.3: PI S-380 Characteristics _______________________________________________________________________ Mechanical Focal Plane _______________________________________________________________________ Range 30 arcsec (150 rad) 5 arcsec Resolution 0.05 arcsec (0.25 rad) 0.008 arcsec Residual Jitter 0.05 arcsec (0.25 rad) 0.008 arcsec First Resonance 600 Hz Total Mass 12 Kg Mirror+PI Dimensions 214 x 115 mm Power Dissipation 2 Watts _______________________________________________________________________ Table 7.4: Hexapod Specifications _______________________________________________________________________ DIMENSIONS Diameter 200 mm Nominal Height 232 mm Central Hole Diameter 75 mm Net weight 7.3 Kg Max power input 3 Watts RANGE OF TRAVEL X/Y Motion (Collimation) 2 mm Z Motion (Focus) 12.5 mm Tip/tilt 0.5 degrees RESOLUTION Z Motion 1 micron X/Y Motion 3 micron Tip/tilt 8 rad (1.6 arcsec) STIFFNESS X/Y movement under load 2 micron/kg Z movement under load 0.05 micron/kg Repeatability & homing accuracy 1 micron First Resonance with PI 300 Hz Max speed in Z-motion 0.4 mm/sec Typical speed in Z-motion 0.05 mm/sec _______________________________________________________________________ drive the f/31 mirror directly. PI delivered a 200mm device in 1991, which was at the time the largest such piezo-driven and momentum compensated device that PI had made. Fig7_5 shows the arrangement of the hexapod, fixed to the top plate in the hub, with the lower plate moving under servo control of the 6 legs. The PI platform is bolted to the lower plate of the hexapod, and contains 6 piezo stacks. The f/31 mirror is epoxied to 3 piezo stacks, which control the mirror fine motion; the other 3 move a counterweight in opposition to provide momentum compensation. Characteristics of the PI tip-tilt platform are listed in Table 7.3 and of the hexapod positioner in Table 7.4. More information on the tip-tilt secondary mirror is available at: http://ccd.ifa.hawaii.edu/docs/tiptilt 7.6 Focusing 7.6.1 Focus sensitivity to temperature Both f/10 and f/31 focus encoders should decrease to maintain focus as temperature decreases, but the f/31 focus is 3 times more sensitive to temperature. An ambient temperature decrease of 1 C caused the telescope tube to contract by 60 micron, bringing the mirrors closer. To compensate for this change, the f/10 focus must be decreased by 20 encoder units (each 2.9 micron). An f/10 focus decrease of 10 encoder units moves the focal plane up by 390 micron, which changes the f/10 image width by 39 micron (2 pixels). Therefore, observers should try to focus to 5-10 units (f/1O focus resolution is 2 units, 6 micron), and refocus if the tube temperature changes by more than 0.5 C. A 1 C temperature decrease requires an f/31 focus decrease of 60 units (microns) to compensate. An f/31 focus decrease of 10 micron moves the focal plane up by 1350 micron, which changes the f/31 image width by 44 micron ( 2 pixels). Observers should therefore try to focus to within 5-10 micron(focus resolution is 1-2 micron), and refocus at f/31 if the tube temperature changes by more than 0.15 C. 7.6.2 Focus settings for common instruments The nominal f/10 Ritchey-Chretien (and f/31) focus lies 12.75 inches (324 mm) below the instrument rotator. The new guider and rack-mount plate have a depth of 8.125+0.25 inches (213 mm). Instrument focal plane positions for common instruments are listed in Table 7.5. Approximate focus settings for common instruments are listed in Table 7.6. Table 7.5: Common IfA instrument and mount dimensions along optical axis ________________________________________________________________________ Instrument or Mount Height inch mm Rack Mount Plate 0.25 7 Atlas Guider 8.125 206 Rack+Atlas 8.375 213 Hippo Polarizer (HSPC) 1.65 42 Rack+Atlas+HSPC 10.025 255 Large Filter Wheel LFW 2.5 63 New Filter Wheel NFW 2.5 63 IfA CCD dewar 0.5 13 QUIRC 4.0 102 8K Mosaic CCD 4.0 102 Blue Beam+Filter Slide BBFS 2.1 52 Wide Field Grism WFGS 0.5 12 Tully Optical Bench HIFI 1.0 25 f/10 FOS 2.7 68 f/31 HARIS 2.7 68 f/31 KSPEC 6: 150: ________________________________________________________________________ Table 7.6: Common IfA instrument configurations and focus settings(1) ________________________________________________________________________ Rack Plate + Atlas + Instrument Depth below Cass. Focus encoder Rotator (mm) f/10 f/31 HSPC+LFW+CCD 331 4850 120 Quirc 315 4450 0 HSPC+Quirc (2) 357(2) 5530 310 HSPC+BBFS+WFGS(+CCD) 319 4650 8K Mosaic CCD 315 4450 0 HSPC+FOS 323 4650 HSPC+HARIS 323 60 KSPEC(2) 363(2) 300 OHS 330 100 Notes: 1 These focus encoder values are for a nominal ambient temperature of 0 C, and take no account of filters which may be included by the user. These focus values will vary with ambient (telescope tube) temperature as noted above. 2 The Atlas guide CCD can move for focus from 4 mm above to 26 mm below nominal focus (320-350 mm). Instruments below this range require insertion of a 75 mm focal-length lens just before the guider CCD to achieve guide focus. This will change the scale in arcsec/pixel on the guide CCD, but not the telescope scale that the guide probe operates in. 7.6.3 Focusing the f/31 secondary mirror The f/10 mirror focus is operated via conventional push buttons which move the mirror in or out. The f/31 secondary is focused and collimated by varying the lengths of the six legs which constitute the hexapod mount. The focus and collimation are controlled by the program tkhex. An example of the focus window of tkhex is given in Fig7_6, and an example of the collimation window is given in Fig7_7. Further information on tkhex is located at: http://ccd.ifa.hawaii.edu/docs/hexapod/tkhex.htm1 7.7 CCDs CCDs are constantly being developed for the 2.2-m telescope; this manual contains a snapshot picture of the CCD status at the time of writing. The latest information can be obtained from the telescope newsletter or from support staff. Most CCDs are presently controlled from a NeXT workstation (running Unix, and the NeXT windowing system). Control may shift onto different Unix workstations (perhaps with the X windowing system) at some time in the future. A typical view of the user interface is shown in Fig7_8. The user interface is very easy to learn. Further details of the User Interface may be found at: http://ccd.ifa.hawaii.edu/docs/Ccd When used for direct imaging, CCD cameras can be mounted directly onto the large filter wheels (see Section 7.8). CCD cameras can also be mounted with optical components such as focal reducers on standard steel rails, generally referred to as 'beams', allowing one dimensional movement along the optical axis for inclusion of extra components. Beams are identified by their color, but differ only in their length, with the blue beam being longer than the green, and hence more appropriate for extended configurations. All CCDs are mounted in similarly constructed dewars. The physical dimensions and overall construction of the standard CCD dewars is shown in Fig7_9. The CCDs currently in use or under development are listed below. Device characteristics (where available) are summarized in Table 7.7. 7.7.1 Tektronix 2048 2048 CCD This is currently the optical detector of choice on the 2.2-m telescope; it is in use nearly every dark run. Cosmetically it is quite good, having only a few small flaws. Its 24 micron pixels give it an ideal scale at either f/10 (0.22" pixels), or at f/31 (0.07" pixels). It is thinned and back-side illuminated, resulting in a high quantum efficiency from blue through to 1 micron. The quantum efficiency of our original Tektronix 1024 x 1024 CCD was measured in the lab. Its performance is shown in Fig7_10. The quantum efficiency is over 90% at 750 nm, but is poor below 400 nm. The Tektronix 2048 x 2048 CCD has similar characteristics from 500 to 900 nm, but has higher QE in the blue. 7.7.2 Orbit 2048 2048 CCD A new 2048 x 2048 CCD made by Orbit Semiconductor has been thinned by Mike Lesser at Steward Observatory. This chip has 15 micron pixels. It has high QE down to the atmospheric cutoff. Its QE is shown in figure 7.10. At the time of writing of this manual, this CCD had not been used at the telescope. 7.7.3 Loral 2048 2048 CCD A Lumigen coated Loral CCD with useful area of 2048 x 1024 15 micron pixels serves as a backup for the Orbit CCD. 7.7.4 8192 8192 mosaic CCD camera A camera comprising of a 4 x 2 mosaic of 4096 x 2048 CCDs(15 micron pixels available for use on the 2.2-meter telescope. When used at f/10, it is normally binned 2 x 2, yielding a 4096 x 4096 image, with 0.275" pixels, and a field of view of approximately 19' x 19'. A custom designed lens acts as both dewar window and field flattener. The CCDs in this camera are unthinned, and have very poor sensitivity in the blue. This CCD camera has an integrated filter slide, and three 150mm square filters (V, R and I) are available. 7.8 Filter Wheels and Filter Slide When used for direct imaging, CCDs are normally mounted on one of two large filter wheels. Each filter wheel has four positions, and is remotely operable. In the older wheel (LFW) filters are inserted in custom design filter holders. These Table 7.7: CCD characteristics ________________________________________________________________________ Pixel Size Read Noise Dark Current Gain Full Well Detector Array Size micron e e /pixel/sec e /ADU ADU Tek 2048 2048 x 2048 24 20 5.4 23,000 Orbit 2048 2048 x 2048 15 Loral 2048 2048 x 1024 15 10 Tek 512 512 x 512 27 large 10,000 Mosaic 8192 8192 x 8192 15 5-20 0.1 2.1 35,000 -60,000 ________________________________________________________________________ Note: Characteristics are different for each chip in the 8k mosaic camera. filter holders are designed to hold filters with 100 mm diameter, and typical thickness of 7mm. Adaptors are available for smaller filters (e.g., 50 mm square, 50 mm round). In the newer filter wheel (NFW), 100mm diameter filters are mounted directly into the wheel, without filter holders. The shutter in the large filter wheel and in the new filter wheel is a Prentor E/100 magnetic shutter (part number 177 666). This is a radially opening shutter, with an aperture of 100 mm. Because it is so large, observers must take care to ensure that their exposures are long enough so that the shutter opening time is small relative to the total exposure. The specified open and close time for the shutter are both 34 ms. This means that for 1% photometry, exposures should be no shorter than 100 x 68 ms= 7 seconds. Repeated usage of the shutter may have degraded its performance somewhat, so a more conservative approach is to limit the shortest exposures to 15-20 seconds. Particular care must be given to flat-field exposures. Twilight flats must be taken when the sky is dark enough so that these longer exposures do not saturate the CCD; for dome flats, the dome illumination must be low enough so that exposures of approximately 20 seconds do not saturate the CCD. A manually operable filter slide, with space for four 50 mm square filters is also available; this can only be used in the "beam" configurations, in which the CCD is mounted on a beam, behind optical components such as the Wide Field Grism Spectrograph (WFGS). 7.9 Optical/UV filters Standard BVRI filters are available (all 100 mm in diameter). These are based on the Mould BVRI system (KPNO-similar to Kron-Cousins). A filter, with central wavelength of 341 nm and bandpass of 32nm is also available. The U'BVRI filter set was designed to have the same optical thickness, so is parfocal - there is no need to adjust focus when changing filters. These filters are all interference filters, and have high throughputs and sharp edges in their transmission curves. Transmission curves for this filter set are shown in Fig7_11. Examples of color equations for these filters with the Tektronix 2048 x 2048 CCD are: B = 2.5 log Counts/Seconds +24.156 -0.155X +0.141(B-V); (7.1) V = 2.5 log Counts/Seconds +23.825 -0.088X -0.058(B-V); (7.2) R = 2.5 log Counts/Seconds +23.837 -0.045X +0.006(B-R);and (7.3) I = 2.5 log Counts/Seconds +23.339 -0.096X +0.011(B-I). (7.4) where X represents airmass. For this CCD/filter set, the filter has an important color term (being significantly redder than the standard filter. The filter has a small color term-it is slightly bluer than the standard filter. The color terms for the standard and broad-band filters are close to zero. 7.10 Infrared Cameras The only infrared camera presently available is QUIRC, which uses a 1024 x 1024 HgCdTe array made by Rockwell. The array consists of 4 quadrants, each 512 x 512, with pixel size 18.5 x 18.5 micron. 7.10.1 QUIRC QUIRC (QUick InfraRed Camera) uses a high quantum efficiency, low read-noise HgCdTe infrared array manufactured by Rockwell Science Center. The camera has reimaging optics which provide a magnification of 1.10, and a cold-stop is built into these optics. Four cold stops are available: one for each of the f/1O and f/31 foci of the 2.2-meter telescope (the f/ 10 cold stop is also used with QUIST), one for the f/8 focus of the CFHT, and one for the f/15 focus of the 61-cm. telescope. QUIRC is run from a command line interface on a Sun SPARCstation. The control program is currently called qcdcom. This program interfaces with the array and its associated electronics via a fiber-optic communication interface. Data are written into FITS files with an effective gain of approximately 4e /ADU. The array is roughly linear up to approximately 40,000 ADU; average pixel values in exposures should generally be kept to below about 20,000 ADU. Short exposures should be avoided, because the shutter is a radially opening type, and because the shutter timing is uncertain at the 10 ms level. This means that, at least at f/10, faint standards should be used. The Elias standards need to be slightly defocused if used with broad-band filters at f/10. Because of delamination concerns, QUIRC is always kept cold. Observers must take care to always fill the dewar properly. Normally, the dewar is filled at the beginning and end of each night. It has a hold time of approximately 24 hours, but this hold time is reduced when the telescope is slewed around the sky. QUIRC has two filter wheels, each with 8 positions. Each filter wheel has one empty position, and one slot is occupied by a polarizer. Therefore, 13 positions in total are available for filters. Five of these positions are always occupied by broad-band filters (J, H, K, r, and Hr). Filters for the 1-0 S(1) line of H2 at 2.12 m, for Br (2.16 m) and nearby continuum (2.26m) are also normally in the dewar. Five slots are available for other narrow- band or special purpose filters. Because QUIRC is kept cold, and only very infrequently opened, it may not be possible to accommodate special filter requirements. Any filter requirements other than the broad-band and common- use narrow-band filters listed above must be clearly listed on any proposal to use QUIRC, and communicated to support staff many months in advance. Transmission curves for the broad-band filters are shown in Fig7_12, and for selected narrow-band filters are shown in Fig7_13. 7.11 f/10 Faint Object Spectrograph(FOS) This CCD spectrograph now replaces the old image tube Cassegrain spectrograph for long slit spectroscopy, providing spatial resolution of 0.49, 0.65 or 1.04 arcsec per 24 micron pixel depending on camera, over a 4 arcmin field. The FOS employs coated transmission optics for both the collimators and cameras, where the latter are commercial Nikon, Canon or Zeiss lenses. Three collimators of focal length 400 mm are provided for peak transmission (98%) in the blue (360-480 nm), visual (420-750 nm) or red (600-1000 nm) wavelength regions. Exchanging the collimator is a delicate procedure and should only be done by experienced observers during daytime. There are 3 standard camera lenses of focal length 180 mm, providing peak transmission (95%) in the blue, visual or red regions, which provide maximum spatial and spectral resolution. Two standard camera lenses of focal length 85 mm provide peak transmission in the visual and red regions, at lower resolution, but are rarely used now. A Zeiss lens of 135 mm focal length and good overall transmission provides the intermediate resolution option. Exchanging cameras should be avoided at night, as it requires two people to lower and support the CCD dewar, and will require refocusing of the spectrograph. A range of standard (fixed) slits can be inserted in a 3 position slide mechanism at the focal plane, where the central position is kept clear for field viewing. Filters can also be inserted in one of the slide positions (at the focal plane) for imaging. A standard Fe-Ar hollow cathode comparison lamp can be remotely activated to illuminate the slit with an f/10 beam. Spectrograph parameters are listed in Table 7.8. The spectrograph beam size is 40 mm, and a range of reflection gratings listed in Table 7.9 provide reciprocal dispersions from 50 to 800 A/mm. Changing gratings and setting grating angles is done manually. A field viewing mirror on a slide adjacent to the grating can be remotely moved into the beam for field inspection or focal-reduced imaging. The spectrograph is generally used with the Tek 2048 CCD, providing the 2-pixel (48 micron) resolution listed below, and an image area of 50 mm ( 40 mm unvignetted image area). Table 7.8: Faint Object Spectrograph Characteristics ________________________________________________________________________ Collimators 400mm blue, visual and red (marked) ________________________________________________________________________ Cameras N180B 180mm Nikkor ED f/2.8 424585 (blue: 360-480 N180V 180mm Nikkor ED f/2.8 3 87244 (visual: 420-780 nm) N180R 180mm Nikkor ED f/2.8 412534 (red: 600-1000 nm) Z135 135mm Zeiss f/2.0 5975158 (broad: 400-1000 nm) C85V 85mm Canon f/1.2 14427 (visual) Z85R 85mm Zeiss f/1.2 6690245 (red) ________________________________________________________________________ Slits m x mm arcsec x arcsec ________________________________________________________________________ 75 x 30 0.7 x 275 140 x 30 1.3 x 275 275 x 30 2.5 x 275 514 x 26 4.7 x 240 ________________________________________________________________________ 100 x 8 0.9 x 74 160 x 8 1.5 x 74 220 x 8 2.0 x 74 720 x 8 6.6 x 74 ________________________________________________________________________ Beam Size 40mm Field Size at Slit 26mm 4 arcmin Image Scale at detector 180mm 20.4 arcsec mm (1); 0.49 arcsec/24 micron 135mm 27.2 arcsec mm (1); 0.65 arcsec/24 micron 85mm 43.1 arcsec mm (1); 1.04 arcsec/24 micron ________________________________________________________________________ Table 7.9: Faint Object Spectrograph Gratings _________________________________________________________________________ Efficiency 85mm camera Grating Blaze at blaze Dispersion Resolution (lines/mm) A (%) A/mm A/48 micron 150 8000 78 800 38 300 6400 87 400 19 500 7700 80 240 12 600 5000 85 200 10 600 10000 76 200 10 900 4500 81 133 6 1200 5000 82 100 5 1200 4000 80 100 5 ________________________________________________________________________ Efficiency 135mm camera Grating Blaze at blaze Dispersion Resolution (lines/mm) A (%) A/mm A/48 micron 150 8000 78 500 24 300 6400 87 250 12 500 7700 80 152 7 600 5000 85 126 6 600 10000 76 126 6 900 4500 81 84 4 1200 5000 82 63 3 1200 4000 80 63 3 ________________________________________________________________________ Efficiency 180mm camera Grating Blaze at blaze Dispersion Resolution (lines/mm) A (%) A/mm A/48 micron 150 8000 78 380 18 300 6400 87 190 9 500 7700 80 110 5.3 600 5000 85 95 4.5 600 10000 76 95 4.5 900 4500 81 75 3.6 1200 5000 82 50 2.4 1200 4000 80 50 2.4 ________________________________________________________________________ Notes: All gratings are 52 mm square ruled area in 58 mm square blanks, mounted in holders. Table 7.10: Wide Field Grism Spectrograph Characteristics ________________________________________________________________________ Collimator 210mm visual (fixed) ________________________________________________________________________ Cameras Z85V 85mm Zeiss f/1.4 Visual 6096959 Z135 135mm Zeiss f/2 Visual 5975158 ________________________________________________________________________ Slits m x mm arcsec x arcsec ________________________________________________________________________ 120 x 33 1.10 x 303 175 x 33 1.60 x 303 200 x 33 1.83 x 303 300 x 33 2.75 x 303 419 x 33 3.84 x 303 603 x 33 5.53 x 303 ________________________________________________________________________ Beam Size 25mm Field Size at Slit 33mm 5 arcmin Image Scale at detector 85mm 22.7 arcsec mm (1); 0.54 arcsec/24 micron 135mm 14.3 arcsec mm (1); 0.34 arcsec/48 micron Table 7.11: Wide Field Grism Spectrograph Dispersion Characteristics with Zeiss 135 mm lens _________________________________________________________________________ Groove/mm Blaze Dispersion Resolution Coverage A A mm with 120 m slit A 400 4800 148 11 7400 420 6400 141 11 7050 600 5000 100 8 5000 600 8500 100 8 5000 7.12 f/10 Wide Field Grism Spectrograph (WFGS) The Wide Field Grism Spectrograph is a compact, all transmission system which can be attached to the 'beam' in front of a CCD, providing low dispersion spectroscopy. The collimator employs visual optics, and has a focal length of 210 mm, giving a collimated beam of 21 mm diameter. A range of cameras and standard slits is available, as listed in Table 7.10 below. A remotely operable slide in the collimated beam allows one of a range of grisms (listed in Table 7.11) to be inserted or removed. Another remotely operable focal plane slide gives a clear or aperture position. The WFGS is generally used at f/6.5 with the Zeiss 135 mm lens, providing an image scale of 14.3 arcsec/mm , or 0.34 arcsec/24 micron pixel over a 5 arcmin field. The resolution listed in table 7.11 is limited by the projected slit width, and will decrease if wider slits are used. 7.13 f/31 High Angular Resolution Imaging Spectrograph (HARIS) The f/31 High Angular Resolution and Imaging Spectrograph (HARIS) is an efficient and versatile two-camera spectrograph. It was built as part of an NSF research project by Dr. Alan Stockton at the IfA to take advantage of the excellent image quality of the University of Hawaii's 2.2-m telescope and f/31 tip-tilt secondary (3 arcsec/mm scale, 4 arcmin field). It can be used with the IfA's CCD and NICMOS detectors for imaging and spectroscopy of faint and/or extended objects in the wavelength range 0.3- 2.5m, at spectral resolutions in the range 300-7000, and angular resolution down to 0.3 arcsec. Users can select one or both of two available camera ports. The long camera port (LFC) can support a CCD detector, at a detector image scale of NO (9.2 arcsec/mm). The short camera port (SFC) can support a CCD detector, usually at an image scale of f/4.5 (20.9 arcsec/mm). The spectrograph may thus be configured for two alternate or complementary observing modes, and rapidly switched between them at night (by switching the grating blaze). Exchanging slits and filters, focusing cameras and tilting the grating to select wavelength may all be managed remotely via an X-window interface on a Unix workstation, communicating with a PC-BitBus controller. Exchanging gratings, switching their blaze for use in the other camera port, and rotating the cassegrain rotator to obtain specific position angles must be done manually. Slits are aligned N-S with the Cassegrain rotator in its standard (270 deg) orientation. Slit Position Angles can be altered by at least 90 degrees either side of this to achieve any Sky PA however; the rotator setting appropriate to a desired slit PA can be found from the tcsi interface. Changing Position Angle must be done with the telescope at the Zenith, and necessitates recalibrating the offset guider; this process normally takes about 15 minutes. Target objects must be carefully aligned on the (known) slit position by imaging either in the detector plane, or at a small below-slit Lynxx CCD. Since HARIS operates at f/31 , targets may be either slow (telescope) guided, or fast-guided on the slit, and the Atlas guider can also be used to command small alignment offsets. Calibration is currently achieved with flat-field and arc lamps attached to the telescope top-end ring, illuminating the dome. An internal system illuminating a retractable white screen in the telescope central baffle is planned. 7.13.1 HARIS schematic overview Light from the f/31 focus of the UH 2.2-m telescope is focussed on the slit-plane of the spectrograph, which consists of a wheel with one open position, and provision for 4 fixed slits of different widths. Maximum slit length is 80 mm (4 arcmin at the f/31 telescope scale of 3 arcsec/mm), and this field is limited by coma increasing to 0.25 arcsec at 2 arcmin off-axis. The slits are tilted to allow for future slit-viewing capability. Below the slit wheel and on a common shaft are 2 filter wheels, each containing one open position and provision for four 4-inch circular filters. The upper wheel is reserved for user filters, the lower for standard Cousins/Mould B, V, R, I filters. A field-view mirror can be inserted below the filter wheels to feed a small Lynxx CCD-TV which can be used to view and align the target object at the slit position, and to check knife-edge (telescope) focus through a wide slit. When this mirror is retracted, light proceeds to a fixed, aluminum-coated collimator of focal length 1253 mm, to form a 40 mm collimated beam. An alternate silver-coated collimator is planned for observations redwards of 4000 A. The collimator folds the beam back to a translation stage which moves to insert either a mirror (for focal reduced imaging) or grating into the beam. The mirror can be toggled between the two (LFC and SFC camera port positions. There are currently 14 gratings providing a range of resolutions at various blaze angles. All gratings can be (manually) inserted with blaze directed to either camera port. The reflected or diffracted-acted beam can be directed towards either the SFC or LFC transmission cameras, which refocus the light onto a CCD detector (SFC) or CCD or NICMOS detector (LFC). Users have a choice of three 180 mm Nikon lenses for the SFC, coated for optimum performance in the Blue, Visual and Red wavelength regions respectively (these are the same as the f/10 FOS N180 camera lenses). There are currently two custom-built 400 mm lenses for the LFC, optimized for use in the Visual-Red or Infra-red wavelength regions. Another LFC camera optimized for the UV is planned. Schematic views of the f/31 spectrograph are shown in Fig7_14 and Fig7_15. 7.13.2 Cameras, Collimators and Slits The available optical and slit components for the f/31 spectrograph are summarized in Table 7.12 below. 7.13.3 Gratings and Resolution The available gratings and the reciprocal dispersions they provide with LFC and SFC cameras are summarized in Table 7.13. The wavelength coverage for the Tek2048 CCD (24 micron pixels) and 256 x 256 NICMOS detector (40 micron pixels), together with the projected slit sizes corresponding to a slit width of I arcsec are also given. Each grating is clearly marked with its grooves/mm, blaze wavelength and camera orientation, on both sides of the grating. When inspecting the grating through the grating access port, you should see SFC or LFC pointing towards the camera you are actually using. If not, insert the grating cover, unclamp and remove the grating, switch the cover to the alternate direction (taking care not to touch the grating surface), and reinsert and reclamp the grating. 7.13.4 Selecting Grating Tilt Angles The Grating encoder has 450 counts/degree (8 arcsec/step), and is generally very repeatable provided it has been initialized correctly. The Grating Home position (after reset) is 18800 (tilted towards the LFC). The grating-horizontal setting is 26075. At the moment, wavelengths are selected by entering grating rotary-stage encoder (GE) settings derived from the grating equation: 2sin(Beta)Cos(17.5 deg) (7.5) lambda = -------------- 10^-7nD 10^-7nDlambda sin(Beta) -------------- 2cos(17.5 deg) (7.6) where lambda is in A, n is the order, D is grooves/mm, 17.5 is the camera-to-collimator semi-angle, and Beta is the dispersion angle. If i is the tilt angle (away from horizontal) measured towards the camera in use, and GE is the Grating Encoder setting, then i = Beta + 17.5 and GE = 26075 +/- i x 450 (7.7) Zero orders to short and long cameras (Beta= 0.0,i= 17.5) are: 33950 = 26075 + (17.5 x 450) (SFC - settings>26075); and 18200 = 26075 (17.5 x 450) (LFC - settings<26075). Grating Encoder settings for various gratings and selected wavelengths are listed in Table 7.14. Other settings can be interpolated from here. 7.14 f/31 JHK cross dispersed spectrograph - KSPEC KSPEC utilizes a cross-dispersed echelle design to provide medium- resolution spectra of the 0.8-2.5 m region, optimized for 2.2 m. The instrument uses two arrays: a HAWAII 1024 x 1024 array is the detector for the spectral information; and a 256 x 256 NICMOS array is the slit-viewing array which images the region of the sky surrounding the slit. The control software runs on a Unix workstation and is similar to the QUIRC camera (see Section 7.10.1). The imaging detector views the region of the sky surrounding the slit. The pixel scale is 0.24 arcsec/pixel; the field of view is approximately 1 arcmin square. Although the slit runs across most of this field, a mask permits only about 15 arcsec of the slit to pass to the spectrograph section. A K filter is permanently mounted in the imaging optics. The slit-viewing capability facilitates the source acquisition, centering, and guiding. The spectrograph detector is a science-grade HAWAII device (1024 x 1024) with relatively few pixel defects in the regions used. For most pixels, the dark current is less than 0.1 e /sec and the read noise is about 12 e . The current device has pixels with high dark current near the bottom edge of the array. The spectrograph section is operated at 73K to reduce the dark current from these pixels and minimize their impact on the data. The pixel scale for the spectrograph detector is 0.167 aresec/pix, and the usable slit length is approximately 17 arcsec. Table 7.15 gives the approximate wavelength ranges and resolutions for the six orders. Sensitivity values are also given. These are I values for a 3 minute on-source integration, after subtracting a similar 3 minute integration. These sensitivity values may be incorrect, and are being reinvestigated. If moving the source along the slit, then the total on-source time equals the total integration time and the numbers in Table 1 can be used to estimate this. If moving the object off the slit for sky frames (e.g., when observing an extended object), then the total integration time required will be two times the total on-source time. Fig7_16 shows a spectrum of an AO star on the spectral array, showing the six cross-dispersed orders. Table 7.16 gives the resolution of each KSPEC slit, based on the measured resolution of slit #4 at the 2.2-meter telescope at 2.2 m in the K order. The width of the slit on the spectrograph is about 3 A wider than the physical size of the slit due to a slight defocus of the spectrograph optics. The defocus is different in each of the orders. For example, with slit #4 the resolutions in the orders are: 650 (K), 665 (H), 674 (J2), 585 (JI), and 571 (12). Slit #4 is commonly used at the 2.2-m telescope. If your observations require a special slit, this must be clearly indicated on your proposal. The dewar must be warmed and opened to change the slit. 7.15 Optical Photometer and Photon-Counting System The Tinsley Photometer, which maybe used on either the 61-cm or the 2.2-m telescope, is a self-contained system with an RCA C31034A GaAs photomultiplier, cooled by dry ice, and operating over a useful wavelength range of 300-900 nm. Quantum efficiencies vary from 38% at 300 nm to 18% at 900 nm. The photometer has a LeCroy MVL100 pulse amplifier/discriminator, and operates under the control of its own Apple 11+ data system with custom counting electronics. The time constant is 124 ns. The photometer is a standard, single beam Tinsley design accepting six apertures. Apertures presently available are listed in Table 7.17; new apertures may be made by visiting observers prior to arrival if needed. There is an internal six position filter wheel which is no longer used however. Observations are now made with an eight position filter wheel sandwiched between the photometer top section and the cold box. Access is via a slide-off cover at the rear of the octagonal filter wheel. The wheel is designed to hold 2 in square filter holders, 12 mm thick, and about 2 dozen of these filter holders are available. Several of these are used for asteroid and comet filter sets, and are 'permanently' labeled and should not be disturbed. Several other filter holders are available for other users of the photometer. 7.16 2.2-m Coude f/34 Spectrograph The spectrograph is arranged in the classical manner, with the axis of the slit-to-collimator beam a continuation of the polar axis of the telescope. The f/33.6 collimator is an off-axis paraboloid which produces a beam of 20 cm diameter from a point source. The cameras are on-axis Schmidt systems, which are selected by rotating the grating to the proper angle and, by using a rotating turret or "spit", bringing the proper camera into the beam from the grating. An overhead trolley arrangement facilitates moving gratings from a storage rack to the mounting turntable; changing gratings requires about 5 min. The spectrograph is supported by a frame of heavy steel beams which is horizontal in the east-west direction and inclined at an angle equal to the latitude in the north-south direction. The north end of the spectrograph frame rests on the telescope pier, while the south end is supported by members which rest on separate piers, also isolated from the building. The temperature in the spectrograph room is not controlled, but is allowed to "float" in response to seasonal variations. The high thermal inertia minimizes diurnal variations. 7.16.1 Coude Slit Instrumentation The stainless-steel biparting slit jaws are controlled by a micrometer which provides an indication of the separation to 0.001 min. The maximum slit width is 2.0 mm. The slit length is limited by a V-shaped dekker which can be adjusted continuously to a maximum length of 50 mm. A 30x3O mm quartz prism is mounted on a vertical slide below the slit jaws. When this is moved up (manually), it blocks the starlight, and folds light from one of 3 sources to the right-hand side into the spectrograph beam. 7.16.2 Comparison Sources Light from any one of three comparison sources may be selected by a rotatable prism. The three sources are currently: 1) Halogen white light (for flat-fields), 2) Thorium-Argon arc lamp and 3) Neon arc lamp. 7.16.3 Filter Mounting A slide for a 50 mm square filter is provided behind the slit. In this position, both the stellar and comparison beams are affected. An arrangement to mount a filter ahead of the slit, in the stellar beam only, is also available. 7.16.4 Coude Cameras Observations can currently be taken with the Tek 2048 CCD (24 micron pixels) or Orbit 2048 CCD (15 micron pixels),which can be mounted at camera number 1, 3, and 4 only. Focusing the CCD is achieved manually on camera 1, and remotely by bitbus control on cameras 3 and 4. The coude spectrograph design includes five cameras of focal lengths increasing by factors of two from 0.3 m to 4.9 m (1 to 16 ft); the significant numerical parameters of those cameras are given in Table 7.18. All cameras are of classical Schmidt design, with single-pass correcting plates (except camera 1 which does not require a corrector) and folding (on- axis) pickoff mirrors directing light to a CCD arranged orthogonally out of the beam. The two shortest cameras each have a choice of two correcting plates-one of fused quartz for wavelengths shorter than about 450 nm, and another of BSC-2 glass for wavelengths longer than about 400 nm. Camera No. 1 does not require a correcting plate. Dispersions listed in Table 7.18 are for a grating of 600 lines/mm used in the second order, and the exposure data are for this dispersion used to expose the Tex 2048 CCD to give a spectrum 0.5 mm wide with a projected slit width of 0.048 mm. The limiting V magnitude is for S/N=100 in a 1 hr exposure. The data are based on experience under good but not exceptional seeing conditions, with no cloudiness. 7.16.5 Coude Gratings The characteristics of the gratings are listed in Table 7.20. All are 20 x 25 cm (8 x 10 in) ruled area, single-diamond gratings, with blaze efficiencies near 50%. Since the blaze wavelength is affected by the spectrograph geometry, slightly different blaze wavelengths are obtained for the 16 ft (No. 1) camera than for all the shorter cameras, and both are given. Reciprocal dispersions for the gratings used in their useful orders are given in Table 7.20. 7.16.6 Grating Angle This is set by unlocking the grating turntable, moving the grating manually to the approximate grating angle (read from an illuminated display in the spectrograph room itself), then fine-tuning the setting (to 0.01 degree) by carefully adjusting the gear mechanism below the grating turntable. Grating angles can be determined from the grating equation adjusted for the camera-to-collimator semi-angle (s/2=5.6deg camera 1, s/2=15.5deg cameras 2-5) appropriately: The Grating Angle in degrees (including a small zero point) is given by: lambda = Beta + s/2 -0.1deg (7.8) where sin(Beta) = 10^-7nDlambda/(2cos(s/2)) (7.9) and n is the grating order, D is number of lines/mm for the grating, and lambda is the wavelength in A. Examples of grating angles are given in Table 7.19. Users should switch all lights off in the coude spectrograph and wait a few minutes for their eyes to adjust to check for any light leaks or dim sources before observing. Do NOT use the fluorescent lights in the coude spectrograph before or during coude observing, as these cause the wall paint to fluoresce dimly. Use telescope oil-pump number 2 (ground floor) to minimize spectrograph vibration during coude observing. Table 7.12: f/31 HARIS Spectrograph Components _______________________________________________________________________ Collimator 1253mm Aluminum coated _______________________________________________________________________ ----------------------------------------------------------------------- SFC N180B 180mm Nikkor ED f/2.8 424585 (blue: 360-480nm) cameras N180V 180mm Nikkor ED f/2.8 387244 (visual: 420-780nm) N180R 180mm Nikkor ED f/2.8 412534 (red: 600-1000 nm) _______________________________________________________________________ LFC 400VR 400mm visual-red 370-1000nm cameras 400IR 400mm infra-red 1-2.5 m ______________________________________________________________________ ----------------------------------------------------------------------- Slits micron x mm arcsec x arcsec _______________________________________________________________________ 170 x 75 0.51 x 225(2) 237 x 80 0.71 x 240 355 x 75 1.07 x 225(2) 530 x 80 1.59 x 240 695 x 80 2.1 x 240 992 x 80 3.0 x 240 1420 x 75 4.3 x 225(1) Notes: 1 Old slit made with blades; other slits are precision machined. 2 Slits machined from thinner material, shimmed to same height (focus) as other machined slits. Table 7.13: f/31 HARIS Spectrograph Gratings and Dispersions ___________________________________________________________________________ Grating Grating Blaze | SFC(l) 180mm Camera | LFC(2)400mm Camera Ref Pitch Wavelength|Dispersion 1-arcsec Slit |Dispersion 0.5-arcsec No. groove/mm A A/mm Proj. micron A/mm Slit Proj. micron ___________________________________________________________________________ 1 300 4200 178 48 80 53 2 300 5000 179 48 80 53 3 300 6400 180 48 81 53 4 300 17000 179 48 80 53 ___________________________________________________________________________ 5 600 4000 90 47 41 53 6 600 5000 91 47 41 53 7 600 6500 92 47 41 52 8 600 7500 92 46 41 51 ___________________________________________________________________________ 9 1200 4000 46 46 21 51 10 1200 5000 46 45 21 50 11 1200 6000 46 44 21 49 12 1200 7500 46 42 21 46 ____________________________________________________________________________ 13 1800 5000 31 42 14 46 ____________________________________________________________________________ 14 86 9600 642 48 289 53 ____________________________________________________________________________ Notes: 0 Resolution and sampling information assumes a CCD with 24 micron pixel size. For the Tek2048 CCD, wavelength coverage is Dispersion multiplied by 50mm. The same coverage and resolution can often be obtained with either camera. The SFC will use a wider slit (more light and less spatial sampling). The LFC requires a narrower slit, provides more spatial sampling, and can reach the highest resolutions. 1 The SFC provides slit-limited resolution (2-pixel projected slit) with a 1-arcsec slit. Wavelength resolutions are 8.6, 4.3, 2.0 and 1.3 A with the 300, 600, 1200 and 1800 line/mm gratings respectively and a 1-arcsec slit. The spatial sampling is 0.51 arcsec per 24 micron pixel with the 180mm SFC. 2 The LFC provides slit-limited resolution (2-pixel projected slit) with a 0.5 arcsec slit. Wavelength resolutions are 4.2, 2.1, 1.05 and 0.66 A with the 300, 600, 1200 and 1800 line/mm gratings respectively and a 0.5 arcsec slit. The spatial sampling is 0.23 arcsec per 24 micron pixel with the LFC. Table 7.14: f/31 HARIS Spectrograph Grating Settings _________________________________________________________________________ 26075 450 x tilt +450 x tilt _________________________________________________________________________ Grating Wavelength Tilt Angle Grating Encoder No. 1/mm A Degrees LFC SFC _________________________________________________________________________ 1-3 300 4000 21.11 16575 35575 5000 22.01 16175 35980 6000 22.91 15765 36385 7000 23.82 15355 36795 8000 24.73 14950 37205 9000 25.64 14540 37615 4 300 12500 J 28.84 13100 16000 H 32.07 11645 22000 K 37.74 9090 _________________________________________________________________________ 5-8 600 4000 24.73 14950 37200 5000 26.55 14130 38020 6000 28.38 13305 38845 7000 30.22 12475 39675 8000 32.07 11640 40510 9000 33.95 10800 41350 _________________________________________________________________________ 9-12 1200 4000 32.07 11645 40505 5000 35.83 9950 42200 6000 39.68 8220 43930 7000 43.63 6440 45710 8000 47.72 4600 47550 9000 51.99 2680 49470 _________________________________________________________________________ 13 1800 4000 39.68 8220 43930 5000 45.65 5530 46620 6000 51.99 2680 49470 _________________________________________________________________________ 14 9000 17155 19.83 17155 34995 1 m 20.08 17040 35111 _________________________________________________________________________ Table 7.15: KSPEC Orders (0.96" slit, 2.2-m telescope, 3 min exposure) _________________________________________________________________________ Sensitivity Order Range Scale Continuum Mag. Line Flux Name ( m) (m pixel (1)) ( 10 (14) Wm (2) m(1)) (10(16)Wm (2)) I1 0.81-0.95 .00014 ... ... ... 12 0.84-1.08 .00022 11.0 ... 43 J1 0.98-1.27 .00029 9.5 ... 12 J2 1.18-1.52 .00034 9.6 11.1 22 H 1.47-1.90 .00042 2.7 11.4 1.8 K 1.96-2.54 .00056 0.94 11.5 3.1 Table 7.16: Available Slits for KSPEC ______________________________________________________________________ Slit widths 2.2-meter CFHT Resolution (K order) Slit # (arcsec) (arcsec) (delta) 1 0.33 0.19 1570 2 0.56 0.32 1030 3 0.79 0.45 760 4 0.96 0.56 650 5 1.08 0.62 570 6 1.47 0.85 430 7 1.65 0.95 390 8 1.92 1.10 335 9 2.11 1.22 310 10 2.61 1.50 250 _____________________________________________________________________ Table 7.17: Optical photometer apertures ________________________________________________________________________ Aperture Diameter Diameter at 61-cm f/15 Diameter at 2.2-m f/10 Number in mm (arcsec) (arcsec) 1 0.12 2.6 1.1 2 0.36 8 3.3 3 0.73 16 6.5 4 1.04 22 9.5 5 1.29 28 12 6 1.48 32 14 7 2.0 43 18 8 2.54 54 23 9 3.65 78 33 ________________________________________________________________________ Note: presently blanked off. Table 7.18: Coude Spectrograph Characteristics ________________________________________________________________________ Characteristic | Camera Number ____________________________________|___________________________________ | 1 | 2 | 3 | 4 | 5 ____________________________________|_______|_______|_______|_______|___ Focal Length (cm) 487 243 122 60.9 30.5 Focal Length (ft) 16.0 8.0 4.0 2.0 1.0 Camera to Collimator (degrees) 11.2 31.0 31.0 31.0 31.0 Reduction factor (slit to detector) 1.38 2.75 5.50 11.0 22.0 Minimum Slit Width(1) ( m) 41 83 165 330 660 Minimum Slit Width(1) (arcsec) 0.11 0.23 0.45 0.90 1.80 Maximum Resolution(2) 93000 44400 22700 11300 5700 Dispersion(3) (A/mm) 1.68 3.42 6.84 13.6 23.0 15 micron pixel in A 0.025 0.05 0.10 0.20 0.40 15 micron pixel in arcsec 0.08 0.15 0.30 0.6 11.21 (Sigma)Photons/pixel/sec(4) ( V=5, =15%) 150 2500 10000 Limiting Vmag, S/N=100 in 1 hr 9 12.5 13.5 ________________________________________________________________________ Notes: 1 For a projected slit width of 30 micron at the detector; this should be increased linearly for larger pixels. 2 Maximum attainable for typical 2nd order grating angles at 5500 A and minimum slit width; this should be decreased linearly for larger pixels. 3 For a 600 line grating in 2nd order. 4 For a star V=5mag, overall optical efficiency 15%, summed along the slit, minimum slit width and seeing 1 arcsec. Larger pixels (X) increase this factor by 15 (2) (wider slit, more wavelength per pixel). Table 7.19: Examples of Coude Grating Angles ________________________________________________________________ Camera ________________________________________________________________ 1 2 600 6965 | 30.33 3/4 2 600 6965 | 41.10 1 2 900 4158 | 27.59 ________________________________________________________________ Table 7.20: Coude Spectrograph Gratings and Dispersions _____________________________________________________________________ | Grating Number Characteristic | 1A | 2A | 3A | 4A _____________________________________________________________________ Lines/mm 600 600 400 900 Blaze Angle (degrees) 14.7 24.0 14.7 24.0 Blaze 1st order, No. 1 0.84 m 1.35 m 1.25 m 0.91 m Nos. 2-5 0.81 m 1.32 m 1.22 m 0.88 m _____________________________________________________________________ --------------------------------------------------------------------- _____________________________________________________________________ --------------------------------------------------------------------- Blaze(1) Dispersions in A/mm for Camera Grating Order (A) | 1 | 2 | 3 | 4 | 5 1A 1 IR 8100 3.36 6.72 13.44 26.9 53.8 600 1/mm 2 Blue 4050 1.68 3.36 6.72 13.44 26.9 2A 1 IR 13200 3.36 6.72 13.44 26.9 53.8 600 1/mm 2 Red 6600 1.68 3.36 6.72 13.44 26.9 3 Blue 4400 1.12 2.24 4.48 8.96 17.92 4 UV 3300 0.84 1.68 3.36 6.72 13.44 3A 1 IR 12200 5.04 10.08 20.16 40.32 80.64 400 1/mm 2 Red 6100 2.52 5.04 10.08 20.16 40.32 3 Blue 4070 1.68 3.36 6.72 13.44 26.9 4 UV 3050 1.26 2.52 5.04 10.08 20.16 4A 1 IR 8800 2.24 4.48 8.96 17.92 35.84 900 1/mm 2 Blue 4400 1.12 2.24 4.48 8.96 17.92 3 UV 2930 0.75 1.49 2.99 5.97 11.95 Notes: 1 Blaze wavelength applies to cameras 2-5, slightly longer wavelengths apply to camera 1 (see above).