SPECTROSCOPY AND SPECTROPHOTOMETRY NETWORK 1. INTRODUCTION During the years 1983-88, the Spectroscopy and Spectrophotmetry Network (SSN) of the International Halley Watch (IHW) was responsible for coordinating, collecting, and archiving a wide diversity of spectroscopic observations of the periodic comets Halley, Giacobini-Zinner, and Crommelin. The personnel of the Discipline Specialist Team in 1982-1989 is listed in Table I. The spectral domain covered the ultraviolet and visible regions, from about 1100 A to 10,000 A, with the ground-based data representing the bulk of the spectra and covering 3000 A to 10,000 A. Spectra of comets obtained in the wavelength regions longer than 10,000 A (1 micron) have been archived by the Infrared Network. The spectra of comet Halley taken from Earth have spatial resolutions of about 400 km at best. Such spectra obtained remotely arise from three distinct sources in the coma: (1) sunlight scattered by the coma dust, (2) neutral molecular gas fluorescing with the solar radiation, and (3) molecular and atomic ions also excited by resonance fluorescence. Solar radiation reflected directly from the nucleus of the comet contributes negligibly to the spectrum observed from Earth, except when a comet is at relatively large heliocentric distances (>5 AU). Spectra in the IHW archive obtained with the instrument aperture centered on the brightest part of the coma are generally dominated by the neutral molecular spectrum of the coma. Spectra offset projected distances >100,000 km from the brightest coma region toward the tail (anti-solar direction) are generally dominated by molecular ions which populate the plasma tail of the comet. Both the coma and plasma tail spectra are composite with an underlying continuous spectrum contributed by the solar radiation scattered by the comet dust. Thus when analyzing the gaseous component of the spectrum, the dust- reflected solar continuum is usually subtracted from the composite spectrum. The spectra of Comet Halley presented in this archive can be found in various forms, both with and without the correction for the solar background continuum. The state of each archive spectrum can generally be determined by reading its fits header. Some observers have submitted spectra of solar system objects or scattered twilight to provide a solar spectrum with the sam instrument used to observe the comet. These spectra have been archived with the Halley spectra and can be used to subtract the background solar spectrum from the comet spectrum. Also included in the IHW archive as appendices are two high resolution spectra obtained directly of the Sun, which, when convolved with the appropriate instrument profile and corrected for the scattered light wavelength dependence (1/lambda), can be used to correct the composite comet spectra for scattered sunlight. Table I. Discipline Specialist Team of the Spectroscopy and Spectrophotometry Network _____________________________________________________________________________ Team Member Affiliation Responsibility _____________________________________________________________________________ Susan Wyckoff Physics-Astronomy Department Discipline Specialist Arizona State University Tempe, AZ 85281 U.S.A. Peter A. Wehinger Physics-Astronomy Department Discipline Specialist Arizona State University Michel C. Festou Observatoire de Besancon Discipline Specialist F-2544 Besancon Cedex France David Schleicher Physics-Astronomy Department Computer System Manager, Arizona State University Scientific Programmer & Post-doctoral Fellow Barbara Boothman Physics-Astronomy Department Computer System Manager & Arizona State University Scientific Programmer David Reisinger Physics-Astronomy Department Computer System Manager & Arizona State University Scientific Programmer Anthony J. Ferro Physics-Astronomy Department Scientific Programmer & Data Arizona State University Assistant R. Mark Wagner Physics-Astronomy Department Post-doctoral Fellow Arizona State University Uri Carsenty Physics-Astronomy Department Post-doctoral Fellow Arizona State University Marvin Kleine Goodyear Aerospace Corp. Software Consultant Tobias Kreidl Lowell Observatory Software Consultant Flagstaff, AZ 86001 Patricia Monger Astronomy Department Software Consultant University of California Berkeley, CA 94720 S.G. Djorgovski Astronomy Department Software Consultant University of California Berkeley, CA 94720 Kyle Baird Physics-Astronomy Department Student Assistant Arizona State University Lisa Engel Physics-Astronomy Department Student Assistant Arizona State University Ichishiro Konno Physics-Astronomy Department Student Assistant Arizona State University Carla Landenburger Physics-Astronomy Department Student Assistant Arizona State University Thomas Larson Physics-Astronomy Department Student Assistant Arizona State University Eric Lindholm Physics-Astronomy Department Student Assistant Arizona State University Gregory Loper Physics-Astronomy Department Student Assistant Arizona State University Steven Tegler Physics-Astronomy Department Student Assistant Arizona State University Jill Theobald Physics-Astronomy Department Student Assistant Arizona State University Maria Womack Physics-Astronomy Department Student Assistant Arizona State University Carol Taylor Physics-Astronomy Department Secretary & Word Processor Arizona State University Loretta McKibben Physics-Astronomy Department Secretary & Word Processor Arizona State University Beverly Dunlap Physics-Astronomy Department Secretary & Word Processor Arizona State University _____________________________________________________________________________ The comet Giacobini-Zinner Spectroscopic Archive contains 433 spectra while the comet Halley archive includes more than 3500 spectra. The spectra of P/Crommelin were originally published in the Archive of Observations of Periodic Comet Crommelin (JPL Publication 86-2, edited by Z. Sekanina). In addition, the P/Crommelin spectra in digital format were included on the P/Giacobini-Zinner compact disk (5.25-inch CD-ROM). The digital archives of P/Giacobini-Zinner and P/Halley contain a significantly greater number of spectra than originally expected. The bulk of the comet Halley spectra was received and archived between 1987 and 1989. The overall effort involved contributions from approximately 150 observers in 16 countries at more than 80 observatories or astronomical institutes. The response of the astronomical community to the IHW archive was most positive and cooperative. We owe a great debt of thanks and appreciation to our colleagues scattered around the world who very kindly provided copies of their spectra for the archive and for the good of all. The following sections provide a brief description of the spectroscopic archive. There are three additional files associated with the Spectroscopy networ located in this appendix directory. They are: SP_CODES.IDX--A table giving the translations for the spectroscopy key- word DIS-CODE. This is a delimited file and can be read into most data- base programs. SP_HIST.DAT--A data file with (X,Y) pairs, giving the number of observa- tions in the spectroscopic archive and the Julian date. SOL_ATLS--A directory containing two solar atlases in FITS format. 2. SPECTROSCOPIC DATA ARCHIVE The spectroscopic archive consists of data obtained by a wide variety of observers, instruments, and techniques. The range of observation sites spans the globe and includes the upper atmosphere and satellites in Earth orbit. The spectroscopic observations of Comet Halley were monitored, but not coordinated, by the Spectroscopy Center at Arizona State University. Various individual observing programs were planned and executed in their entirety by the observers who contributed data to the archive. Occasionally the observations were made by observers who had no expertise in cometary spectroscopy. Fortunately, there was such an overwhelmingly universal interest in Comet Halley that virtually every large aperture telescope equipped with spectroscopic instrumentation obtained at least a few spectra of the comet. Thus, the spectroscopic archive comprises data obtained with a very diverse array of state-of-the-art instruments and detectors in the years 1985-1986 and represents a unique set of observations of Comet Halley. In 1910, the state-of-the-art detector was the photographic plate. The present archive includes a small percentage (<0.5%) of spectra digitized from photographic plates, which is a testimony to the technological advances made in astronomical detectors during the past 76 years and especially in the 1970 and 1980s. Our task to archive this diverse data set was a challenging one. Because of the diversity of the data, we decided to exercise as little editorial prerogative as possible when considering data to be included in the archive. Our standard keywords are listed in Sec. 11. They were used to explain a large variety of different types of data, even though no finite set can explain all possible types of data. For example, in the case of the International Ultraviolet Explorer (IUE) satellite, the site location (in a geosynchronous orbit) could not be described in terms of latitude, longitude, and elevation, since these values constantly changed. In this case, we entered mean values for the latitude and longitude of the satellite' position projected onto the Earth, and a negative value for the elevation was used as a flag that this elevation is inherently variable. The spectroscopic data in the Comet Halley archive consist of two basic types: one-dimensional and two-dimensional spectra. In the case of one- dimensional spectra, the data are measurements vs. wavelength of the flux fro the comet within a solid angle determined by the size of the spectroscopic instrument aperture projected at the comet. For the two-dimensional spectra, a spatial dimension is added covering the length of the slit projected at the comet. Thus a two-dimensional spectrum contains flux information for a set o points, determined by the slit length used. The two-dimensional spectra can be treated as a normal image, as far as manipulation and display. The only difference from an image is that one dimension is wavelength and the other is spatial. The one-dimensional spectra might be displayed as a one-dimensional image, but a graphical display, plotting flux vs. wavelength is more conventional. We adopted a policy in producing the archive to minimize editing and altering the data submitted to avoid their interpretation. Thus we made no attempt at calibrating the spectra that were submitted in raw, unreduced form. Instead, we included calibration spectra in the archive, so that users may manipulate data in the form submitted by the observer, and not subjected to potential misinterpretation or changes by us as editors. We felt that this policy best protected the integrity of the data for use by future generations of astronomers. We have taken the position that we, as archivists, should not be involved with actual reduction of the data, which is why we requested that observers submit data to us in reduced form (i.e., F(lambda) vs. lambda versus rho). There are valid arguments on both sides of the issue whether submitted data should have been reduced or left in their raw form. Future workers may have better reduction techniques and the original observer may not be interested in doing the full reduction, or may not have experience in reducing cometary spectra. On the other hand, the observer, who is familiar with the instrument used, probably knows his data best, and is in the best position to make judgements as to what reduction techniques are proper. We have taken the position that fully reduced data (flux and wavelength calibrated) are the norm, but have archived what was sent. Most of the data in the archive are fully reduced, or as fully reduced as possible (in some instances, such as high spectral resolution data, flux calibration may not be possible). In some sets, the data are raw, essentially as observed. Hopefully with the raw data sets, other calibration data have been included as well, although this is not always the case. When calibration frames are available, their type should be clear from the OBJECT keyword. The type of data presented can be determined from DAT-TYPE. Data and calibration frames should be correlated, based on time and date of observation, observer, and observatory. A major source for information regarding observatories (location, name, elevation, etc.) was the Astronomical Almanac, published by the US Printing Office. This was only used when the observer did not furnish exact information, such as latitude and longitude of the observatory. As described in the FITS Keywords Descriptions, the OBSERVER and SUBMITT keywords contain the name of the first observer or submitter. If there are more than two names, all but the first name go in a special COMMENT ADD. OBS. field. Most names are generally not a problem. However, due to the FITS conventions, there can be problems with names which contain an apostrophe. For example, OBSERVER = 'A'HEARN,M' is valid (the apostrophe after A is withi the minimum eight characters for the keyword value), but OBSERVER = 'FELDMAN,P/A'HEARN,M' is not valid (it would likely be read in as OBSERVER = 'FELDMAN,P/A'). We have tried the solution of replacing the apostrophe with blank. Thus we have OBSERVER = 'FELDMAN,P/A HEARN,M'. This may present a slight problem when a search is made spelling the name A'Hearn properly. The airmass of the observation was not always submitted to us. When we were given hour angles, we did calculate the airmass. However, there are man submissions for which no airmass is given. The proper airmass, if needed, ca be obtained from the ephemeris for that time and the location of the observa- tory. There are no standard ways for describing the position of a slit with respect to a comet. To describe the location of the slit. we chose three measurements: (1) The distance between the center of brightness of the comet and the center of the slit, measured in arcseconds (SEPNUC); (2) the angle, measured in degrees from north throught east, to the center of the slit (ORIENT); and (3) the angle, measured in degrees from north through east, of the beginning of the slit (POSANG). Unfortunately, most observers do not use these exact measurements. Often, the only measurement refers to the number of arcseconds sunward or tailward. We have tried to convert the pointing angles given to our three parameters as accurately as possible. Often we used the comet's ephemeris for converting from tailward-sunward coordinates to those used in the archive. It is a general convention that if the nucleus is in the data frame, the slit is "on the comet," even though, strictly, SEPNUC is not zero, but it is very small. 3. TRIAL RUNS 1983-85: RECOVERY, SPECTROSCOPIC HIGHLIGHTS, LESSONS LEARNED The first trial-run observations and archiving campaign centered on Periodic Comet Crommelin, which was recovered August 11, 1983 by L. Kohoutek at the Calar Alto Observatory in Spain and independently by S. Wyckoff and P. Wehinger at the Kitt Peak National Observatory in Arizona when the comet's total V magnitude was 19.7. While P/Crommelin only reached a maximum total brightness of 7.5 mag, spectroscopically it was very rich in NH2. Among the lessons learned in this trial run, the range of dates selected for coordinated observations was not optimized for best coverage, i.e., the largest elongation from the Sun and the maximum brightness. Due to limited advanced notice of the coordinated observations, only a small number of observers participated in the P/Crommelin campaign. The second trial run involved Periodic Comet Giacobini-Zinner. Pre- recovery images were obtained with CCDs in May 1984 by H. Spinrad and M. Belton (private communication) using the KPNO 4-meter telescope, on January 28, 1985 by R.M. West using the ESO/Danish 1.5-meter telescope, and on March 28, 1985 by M. Belton and P. Wehinger using the KPNO 0.9-meter telescope. Subsequently, S. Djorgovski, H. Spinrad, G. Will, and M. Belton recovered P/Giacobini-Zinner on April 10, 1989 with the KPNO 4-meter reflector, when th comet's total brightness was 22.5 mag. P/Giacobini-Zinner was the first come to be visited by a spacecraft, when the NASA International Cometary Explorer (ICE) passed through the plasma tail of this comet, 7800 km from the nucleus, on September 11, 1985 at 11:02 GMT. What lessons were learned in this case? Here the encounter was well timed for coordinated simultaneous ground-based observations in predawn hours in the U.S. desert southwest (11:02 GMT = 04:02 MST). However, very limited information was provided by NASA's Mission Control to ground-based observers prior to the ICE encounter. Details were not available about such things as the track orientation of ICE through tail of the comet and the rate of motion across the tail. Only about 5% as many data were acquired on P/Giacobini- Zinner as compared with P/Halley. There was little, if any, formal announcement to the comet community of plans to create a digital archive of P/Giacobini-Zinner data. There is one general remark to make about all three periodic comets with regard to their recoveries. P/Crommelin, P/Giacobini-Zinner, and P/Halley were all recovered during dark of the moon on telescope time originally assigned to quasar imaging with CCDs. Since the orbits were well established the relatively small fields of the CCDs were successful in the recovery efforts. The situation was different for P/Brorsen-Metcalf, which was some 15 degrees away from its predicted position due to neglected non-gravitationa forces since the last apparition in 1919. Prior to P/Halley's 1980's return, bright comets of special interest included: Humason 1962 VIII, in which CO+ was detected; Bennett 1970 II, whic had a high dust content; Kohoutek 1973 XII, in which H2O+ was first detected; West 1976 VI, in which CO+ and CO2+ were both detected; and IRAS-Araki-Alcock 1983 VII, in which S2 was detected close to the nucleus. Bright comets following P/Halley in the period 1987-90 included: Wilson (1987 May), total magnitude, m1 = 5.0 mag; P/Brorsen-Metcalf (1989 August), m1 = 5.6 mag; Okazaki-Levy-Rudenko (1989 December), m1 = 5.8 mag; Austin (199 May), m1 = 5.0 mag, and Levy (1990 September), m1 = 4.0 mag (estimated). P/Brorsen-Metcalf has a period of 70 yr, similar to that of P/Halley, but the former comet is in a prograde orbit. 4. RECOVERY OF PERIODIC COMET HALLEY P/Halley was recovered 1982 October 16 by David Jewitt, Alan Dressler. Maarten Schmidt, and others using the Palomar Observatory 5-meter telescope. Lest it be lost in the sands of time, we wish to point out that Alan Dressler's efforts were crucial in leading to the recovery. Dressler suggested that Jewitt make use of an occulting mask to suppress the scattered light from an 8th magnitude star close to the predicted track of P/Halley on October 16, 1982. Without the occulting mask, the 25.9-magnitude comet would have been lost in the star's light. However, with Dressler's occulting mask, plus dark clear sky and good seeing, the recovery attempt was a success. Others who contributed in their community-minded spirit to help with the recovery were Maarten Schmidt, who gave up some of his time (scheduled for work on quasars). James Westphal and James Gunn were essential in making the CCD system work. Barbara Zimmerman provided software expertise. Finally, the ephemeris by Donald Yeomans was also essential. Prior to the actual recovery of P/Halley, numerous attempts were made over a five-year period starting in 1977. Early efforts of note were those of M. Belton and H. Butcher at KPNO using the 4-meter telescope with the cryogenic camera, a CCD mounted in a semi-solid Schmidt camera cooled to liquid nitrogen temperatures. Part of the difficulty in recovering P/Halley was the comet's location close to the galactic plane with densely populated Milky Way fields. With the long term future in mind, it is conceivable that this past apparition of P/Halley was the last this comet was recovered as such. With the advent of larger ground-based and space-based telescopes, P/Halley may never be lost again as it heads out to aphelion beyond the orbit of Neptune. Even the early spectroscopic observations of P/Halley were hampered by the comet being located in rich Milky Way fields from October 1983 till February 1985. All spectra of the comet acquired prior to February 1985 were obtained using blind offsets with the slit oriented along the position angle of the predicted track of the comet. Precise coordinates, determined to an accuracy of 0.3 arcsec, were determined using SAO stars and from them secondary astrometric standards were established. Then, using blind offsets from these secondary standards, the slit was positioned and rotated to the proper position angle. For each observation on a given night, about a day's work was involved in setting up the astrometric standards, which were measure from glass copies of the National Geographic Society-Palomar Sky Survey (1955 edition). In the case of the Kitt Peak National Observatory's 4-meter spectra a slit width of 3 arcsec and a slit length of 4.5 arcmin was employed. 5. SPECTRA ON THE INBOUND JOURNEY: HELIOCENTRIC DISTANCES FROM 7 TO 4 AU The Spectroscopy Network was also responsible as a kind of catalyst to help observers acquire key data sets in the course of the eight years centere on the 1986 apparition of Comet Halley. In this Halley campaign, the first phase of spectroscopic observations can be described as pre-sublimation phase during 1983-1984. The level of detection was so faint in these years (total magnitude fainter than 23) that no well-defined color or color index could be derived prior to early 1985, when sublimation had begun. During most of the preperihelion phase (1982-85) P/Halley was located in a relatively crowded Milky Way field making it difficult to acquire the comet and obtain reliable spectra at very low light levels. The first non-spectroscopic evidence of the developing coma were CCD images obtained on September 27, 1984 by S.G. Djorgovski and H. Spinrad using the KPNO 4-meter telescope. A 6 arcsec coma was detected in the red region (6000-7000 A). Subsequently, in November 1984 A. Crotz acquired additional CCD images with the KPNO 4-meter showing a similarly extended coma. Spectra obtained during the period October 1984-January 1985 showed no spectroscopically detectable emission features. Some observations, particularly in the U.S.A., were hampered by cloudy weather during this period. However, the increasing intrinsic light of the comet was the first evidence of a developing coma. Low resolution spectra (12-15 A) during this period were obtained by a team at Kitt Peak National Observatory (M. Belton, H. Spinrad, P. Wehinger, and S. Wyckoff) using the 4-meter telescope with a grism spectrograph and CCD. All the observations during 1983-1984 were acquired using blind offsets from stars near the comet's predicted track with the slit oriented along the comet's track on the sky and the telescope tracking at the comet's rate in right ascension and declination. During these years the total light of the comet was fainter than magnitude 22. These low signal-to-noise spectra, which showed a reflected solar continuum, were acquired between October 1983 and March 1984. None of the 1983-84 spectra showed any emission features that would have been indicative of the comet's gas production. Spectra of P/Halley obtained in October 1984 were collapsed to one-dimension. The cross-cut spectra first appeared to show evidence suggestive of an extended coma. However, later very careful astrometry by Belton showed that the "coma was due to faint Milky Way field stars. The early interpretation suggesting a developing coma was reported by Belton (1985, Science 230, 1129) in his review, "Comet Halley: the Quintessential Comet". Thus, in the future, one should be cautious of early detection of the coma, unless, of course, in situ measurements are made from a spacecraft. By February 17, 1985 the first spectroscopic evidence for the onset of sublimation was detected, by Spinrad observing with the KPNO 4-meter telescop and by Wyckoff observing with the 4.5-m Multiple-Mirror Telescope (MMT). Spinrad observed the [O I] 6300 A line (cf. Belton 1985, Science 230, 1129), while Wyckoff et al. (1985, Nature 316, 241) detected the CN(0,0) violet system at 3880 A. Barker, Cochran, and Cochran at the McDonald Observatory detected CN with the 2.7-meter reflector on the same night. Later, on August 23, 1985, Spinrad detected the C2 Swan system using the Lick Observatory 3-meter telescope. On October 17-20, 1985 E.M. Burbidge at Lick, S. Wyckoff at the MMT, and B. Peterson at the Anglo-Australian Telescope all detected the H2O+ (8,0) vibronic band, while the comet was 2.2 AU from the Sun, nearly twice as distant as any previous H2O+ detection in a comet. 6. SPECTRA ON THE OUTBOUND JOURNEY: HELIOCENTRIC DISTANCES FROM 4 TO 8 AU On the outbound journey, the last emission band detections were those of CN(0,0) and C3 (4040 A) on January 30, 1987 at 5.0 AU by Belton and Wehinger, who used the Cerro Tololo Interamerican Observatory 4-meter telescope. The outbound production rates were 15 times greater that the inbound rates. The extent of the coma from the long slit spectra obtained by Belton and Wehinger was 32 arcsec in diameter. Other evidence for the apparent inertia in the comet's outgassing processes were also evident, for example, the CCD imaging data acquired by R.M. West and his team at the European Southern Observatory. Attempts to detect the last emission due to the CN violet system were made in February 1988 by S. Tegler, S. Wyckoff, and P. Wehinger using the KPNO 2.2 meter telescope. Only a scattered solar continuum was detected. West found coma of more than 30 arcsec in diameter in April 1887 and more than 10 arcsec in January 1988 at 10.1 AU. Finally, in February 1990, West (IAU Circ. 5059 reported no detectable coma in the visible at a level of 29 mag/arcsec sq. Table II. Major Spectroscopic Developments as a Function of time and heliocentric distance r _______________________________________________________________ r = 8-5 AU Extended dust continuum develops (1984) r = 6.5 AU Photometric detection of development of coma (1984) r = 4.8-4.5 AU Onset of sublimation in CN(0,0) 3883, C3 4040, [OI] 6300 (February-April 1985) r = 4.2-2.6 AU Comet lost in Sun's glare, inbound (May-July 1985) r = 2.4 AU Neutral coma develops, C2 Swan system (August -September 1985) r = 2.2 AU H2O+ plasma tail detected (October-November 1985) r = 1.2-0.8 AU Brightest preperihelion phase (January 1986) r < 0.7 AU Comet lost in Sun's glare r = 0.5 AU Comet reaches perihelion (February 9, 1986) r = 0.8-1.0 AU Brightest post-perihelion phase, spacecraft encounters (March 6-14, 1986): VEGA-1, VEGA-2, Suisei, Sakigate, Giotto, ICE r = 1.2 AU Highest spectral resolution spectra acquired of neutral species: CN(0,0) R-branch, C2(1,0), and C2(0,0) rotational lines. Identification of C{13}N{14} in CN(0,0) violet system R-branch lines (April 4-7, 1986) r = 1.4 AU Highest signal-to-noise spectra of the plasma tail were acquired (April 12-15, 1986) with the CTIO 4-meter telescope r = 2.46 AU Neutral molecular spectrum continues (June 30, 1986) r = 2.5-4.4 AU Comet lost in Sun's glare, outbound journey (July-October 1986) r = 4.5 AU Neutral coma continues (December 1986) r = 4.8 AU Neutral molecular species still detected, including CN(0,0), C3 4040, and very weak C2 Swan system (January 30, 1987). CN band strength 15 times greater than at 4.8 AU pre-perihelion r = 6.5 AU Dust continuum 32 arcsec diameter detected spectroscopically (February 1988), no emission features r = 10.5 AU Imaging shows continued existence of dust coma, 20 arcsec diameter (May 1989) r = 12.5 AU Imaging shows no further evidence of coma down to 29 mag/arcsec sq. (Feb 21-24, 1990) _______________________________________________________________ 7. COORDINATION AND COMMUNICATIONS At the start of the IHW campaign, communications were limited to telephone telex, and air mail. By 1985 electronic mail was first becoming available to more than half of the observers, and by the end of the campaign (1989), more than ninety percent of the observers had access to some form of electronic mail. During the period April 1985 to early 1987, an electronic bulletin board was operated for the IHW at Arizona State University. By October 1985 the Halley Hotline was linked to GTE's Telenet, the largest public data network in the United States. Observers could leave messages and read current updates in five subdirectories, including: spectrophotometry, imaging, astrometry, space missions, and ephemerides. From November 1985 to June 1986, some 3000 log-ons were rewcorded by observers, space scientists, laboratory spectroscopists, and other interested parties, representing 22 states in the United States, and 12 other countries. Access within the United States was kindly provided by a corporate gift of GTE Telecommunications, who provided free access to Telenet. Overseas users paid the transoceanic charges through their countries post, telephone, and telex companies to access the Halley Hotline. International users included: United Kingdom, France, Federal Republic of Germany, the Netherlands, Belgium Italy, Spain, Austria, Canada, Japan, Chile, and Australia. 8. REMARKS ABOUT GLOBAL COMMUNICATIONS From a historical perspective, the period 1982-1990 was a time of major technological advancement with regard to digital computers, local and wide area computer networks, and national and global computer links. When the IHW began, we used the conventional postal system, the telephone, and the telex. The telex provided the widest possible link for communications, though it was slow and sometimes unreliable in some countries, and was not available in others. Sometimes no replies came through for months after a telex had been sent. In terms of the technology of our times, the common modes of communication from 1982-85 included airmail (2-15 days in transit), international telex (immediate, 110 baud) used to most countries but not widely used in the United States, and telephone (immediate, voice communication, expensive). By 1985 electronic mail via Bitnet was coming int use. Bitnet, a system of store and forward from computer to computer, was promoted by IBM including IBM's support of a trans-Atlantic link from the United States to Western Europe. This first electronic mail system was free to the user and grew rapidly. The typical transit time, for example, for a one page letter from Arizona to France, was 2-3 minutes when all intermediate nodes were operating, and longer at times of heavy traffic. At the same time, the Committee Consultatif International de Telex et Telephone (CCITT) had already set up the X.25 standards for transferring ASCI files over international telephone networks. The X.25 protocol uses a mode o packet assembly and disassembly (PAD) software which enables files to be transferred in a machine-independent manner at a rate of 9600 baud with error checking routines. GTE Telenet Corporation, which operated the largest public-data network in the United States in 1985-86, used X.25 protocol for the transfer of files, for remote log-ons, and for links to international communications networks. The X.25 protocol provided a much faster and direct link from node to node, in contrast to the slower store and forward system of Bitnet. 9. SPECTROSCOPIC DATA: MAGNETIC STORAGE MEDIA When the first IHW General Meeting was held in August 1982 in Patras, Greece, in conjunction with the IAU General Assembly, some members of the IHW Steering Committee expressed concern that a significant percentage of the spectroscopic data would be recorded on photographic plates and would require subsequent digital scanning with a microdensitometer. Our early estimates were that the majority (70-80%) of the spectra would be recorded in digital format. In fact, virtually all the spectroscopic data that we received were in digital format. A small percentage (less than 3%) of spectra originally recorded on photographic plates were scanned with digital microphotometers by observers at their institutes and were submitted on magnetic tape. At the time the IHW was organized, photographic plates were already on their way out. Nearly all observatories that had instrumentation to record useful slit spectra of comet Halley had some kind of digital detector system. 10. FITS FORMAT In order to standardize the data documentation and calibration, we provided observers with: (1) detailed flux standard star calibration data using existing compilations by K. Strom from the Kitt Peak National Observatory; (2) with guidelines to creating FITS (flexible image transport system) headers, based on the FITS definitions established by Wells, Greisen, and Harten (1981, Astron. Astrophys., Suppl. Ser. 44, 363), and by Greisen an Harten (1981, Astron. Astrophys., Suppl. Ser., 44, 371). The initial motivation for creating FITS formatted data tapes was driven by radio astronomers, who wished to intercompare and/or combine data sets obtained wit different radio telescopes. The IHW disciplines have introduced additional FITS keywords to describe various aspect of their data so that the archive could be properly documented. Efforts have been made to coordinate common keywords between various disciplines. During the 1980s FITS format became an international standard used by ultraviolet, optical, infrared, and radio astronomers. In addition, public domain data reduction and data analysis packages, such as IRAF, STSDAS, AIPS, and MIDAS have been designed and writte to handle data written in FITS format. The FITS standards were initially established to read and write data on magnetic tape in machine-independent format. Since then various types of more compact data-storage media have been developed. The medium selected for recording the IHW archive is on 5.25-inch diameter compact disks with read-only-memory (CD-ROM). FITS standards have been modified to handle data recorded on CD-ROMs. Each CD-ROM holds approximately 650 magabytes. With th advent of CD-ROMs, another very similar machine-independent formatting system was established, called PDS for Planetary Data System, by space scientists wh are primarily involved in the collection and archiving of spacecraft data on missions within the solar system. Subsequently, routines have been written t convert data from FITS to PDS and from PDS to FITS format for use with different software packages and with different applications. 11. SSN FITS KEYWORDS Below is a description of the keywords used in the FITS headers of the data from the International Halley Watch Spectroscopy and Spectrophotometry Network (IHW SSN). Each keyword is listed in capital letters, followed by an initial, indicating whether the variable is a logical (L), integer (I), floating point (F), or character string (C). For several FITS keywords, there are several forms of the keyword, usually relating to various axes. In these cases, the keyword is listed as XXXXn, where n is the number of the axis which the keyword describes. o SIMPLE -L- Does the file conform to the FITS format? If yes, the keyword is set to T. Otherwise the keyword is F. This keyword should be set to true for all SSN files. o BITPIX -I- Keyword contains the number of bits in each picture element. This value is either 16 or 32 for SSN data. o NAXIS -I- Keyword contains the number of axes in the data. One dimensional spectra have a value of 1. Two dimensional spectra a value of 2. o NAXISn -I- n is a number in the range of 1 to NAXIS. Keyword contains the length of axis. NAXIS1 is the dimension of the fastest varying axis in the data. NAXIS2 is the second fastest varying axis, etc. o EXTEND -L- Does the file contain extensions conforming to the FITS standards? If yes, the keyword is set to T. Otherwise the keyword is F. For all SSN data files, EXTEND=F. o OBJECT -C- Keyword contains the name of the object of the data. o FILE-NUM -I- This is a running number of the files sent to the archive. All values have six places and, for the SSN, begin with 7. For P/Halley, file numbers are in the range of 701000 to 709999. o DATE-OBS -C- Universal Time (UT) date of middle of data acquisition. Date is given in the FITS standard of day, month, year (DD/MM/YY). o TIME-OBS -F- Fractional part of day, indicating the UT time of the middle of data acquisition. The keyword has a value ranging from 0.0 to 0.99999. o DATE-REL -C- Date the submitter or submitters agree to release their data to the public. o DISCIPLN -C- IHW Discipline. For the SSN the value is always SPECTROSCOPY. o LONG-OBS -C- East Longitude of observation station. Keyword value range is from 00/00/00 to 359/59/59. o LAT--OBS -C- Latitude of observation station. Degrees north or south are indicated by a preceding '+' or '-', respectively, 0 degrees has no sign. o SYSTEM -C- Station system code. Keyword is a number of the form 7nnnttii where 7- Discipline number (SSN) nnn- IAU Observatory Number tt- Telescope Number, as assigned by the IHW Large Scale Phenomena Network (LSPN) ii- Instrument/Detector Number, assigned by the SSN, and corresponds to DD in DIS-CODE keyword o OBSERVER -C- Name of observer. If more than two observers, first observer listed, followed by ET AL. Additional observers are listed in COMMENT ADD.OBS. keyword. o SUBMITTR -C- Name of the person or persons who submitted the data to the IHW-SSN. o SPEC-EVT -L- If true, some special event occurred during observation. See COMMENTs and HISTORYs for more information. o DAT-FORM -C- Form of the data. One of: ASCII, STANDARD, HARDCOPY, NODATA. o DAT-TYPE -C- Type of data being submitted. One of: UNKNOWN, REDUCED DIGITAL, RAW DIGITAL, PHOTOGRAPHIC, OBJECTIVE PRISM, INTERFEROMETRIC, SPACE BORNE. o DIS-CODE -C- This keyword contains a 9 digit integer with the digits defined as DDCCWWWRQ where: DD - Detector/Instrument combination. This is a unique number for each combination and has been assigned by the SSN. This value is the same as ii in the SYSTEM code. CC - Configuration (grating, grating tilt, filter, aper- ture size, order, etc.) for a given telescope and detector/instrument combination. WWW- Wavelength range in Angstroms, included in the data. A binary coding scheme is used to specify a unique number for a unique set of wavelength regions. The number is the sum of all defined values for each spectral region in which data is submitted: 1 = <3000 2 = 3000-3499 4 = 3500-3999 8 = 4000-4999 16 = 5000-5999 32 = 6000-6999 64 = 7000-7999 128 = 8000-10000 256 = >10000 Example: Range of 3700-6400 A would be 4+8+16+32=60. R - Resolution. This parameter is based on the spectral resolution (FWHM in Angstroms). 1 = <= 0.05 2 = > 0.05 - 0.2 3 = > 0.2 - 1 4 = > 1 - 5 5 = > 5 - 10 6 = > 10 - 20 7 = > 20 - 50 8 = > 50 - 100 9 = > 100 Q - Quality of the data. We adopted a qualitative judge- ment for this parameter, and the values are the same as the QUALITY keyword. 0 = Unknown 1 = Excellent 2 = Very Good 3 = Good 4 = Fair 5 = Poor o OBSVTORY -C- Name of the observatory from which data were obtained. o ELEV-OBS -F- Elevation of the observing station (meters). o TELESCOP -C- Telescope used for observation. Where possible, the telescope name as listed by the Astronomical Almanac has been used. o INSTRUME -C- Instrument and detector used for obtaining data. o RESOL-SP -C- Approximate spectral resolution of data (Ang- stroms). o RANGE-SP -C- Approximate spectral range of data (Angstroms). o EXPOSURE -F- Exposure or integration time (seconds). o APERSIZE -C- Entrance aperture size, or slit width and length of instrument or detector (arcsec). o Airmass -F- One of the following: AIRM-BEG - Airmass at beginning of observation. AIRM-END - Airmass at end of observation. AIRM-MID - Airmass at midpoint of observation. AIRM-AVE - Average of airmass of observation. o SEPNUC -F- Separation between the comet nucleus and center of slit or aperture (arcsec); see figure below. o ORIENT -F- Position angle of slit or aperture center with respect to the comet nucleus, measured north through east (degrees), ranging from 0 to 360 degrees; see figure below. o POSANG -F- Position angle of slit measured from north through east (degree), ranging from 0 to 360 degrees. Two dimensional spectra only. See COMMENT and HISTORY sections for observers' variations of this definition. o PIXSCALE -F- Image scale at detector in arcsec per pixel. Two dimensional spectra only. o QUALITY -I- A subjective, qualitative estimate of the data. Values used: UNKNOWN, EXCELLENT, VERY GOOD, GOOD, FAIR, and POOR. o CTYPEn -C- n is a number between 1 and NAXIS. Name of the in- dependent variables: LAMBDAA - Wavelength (Angstroms). VELOCITY - Velocity (km/sec). PIXELS - Pixel number. RHO - Projected distance (arcsec). OTHER - Described in a comment. o BUNIT -C- Name of dependant variable: FLAMBDA - Flux per wavelength (erg/cm2/s/A). FNU - Flux per frequency (erg/cm2/s/Hz). RAYLAMBDA - Flux per wavelength (Rayleighs/A). RELINS - Relative intensity. COUNTS - Counts or count rate (counts/second). DENSITY - Photographic density. OTHER - Described in a comment. o CRVALn -F- Reference point for CTYPEn. o CRPIXn -F- Reference pixel location corresponding to CRVALn. o CDELTn -F- Increment in CTYPEn per pixel. o HISTORY DATE-REC -C- Date on which file was received by the IHW SSN. o HISTORY DATE-CMP -C- Date on which file archiving had been completed. o HISTORY REDUCED -C- Known data reduction steps. o HISTORY -C- Other history if known. o COMMENT ADD.OBS. -C- Additional observers. o COMMENT NOTE -C- Some important note on the data extracted from COMMENT or HISTORY fields which will appear in the printed archive listing. o COMMENT PROC FILE and ORIG. FILE -C- Comment regarding original file identification of the submitted file. Often file name consists of position of file on original submission tape. Used for SSN archiving. o COMMENT REPLACE -C- A note that this file supercedes another file (previous file would have been deleted from the archive). o COMMENT -C- Additional comments about the data. o DATAMAX -F- Maximum value of dependent variable. o DATAMIN -F- Minimum value of dependent variable. o BSCALE -F- Scale factor to convert FITS pixel values to true values. Used to convert FITS data to original data values. DataValue = BZERO + BSCALE * FileDataValue o BZERO -F- Offset applied to true pixel values. o END Signals end of FITS header. 12. SSN OBSERVERS AND SUBMITTERS The observers and submitters participating in the SSN activities are presented alphabetically in Table III, while Table IV lists chronologically the submitted contributions of the spectra and Table V shows a brief statistical distribution of the contributing countries. The institutional affiliation given for each observer may be different from the institution where he/she originally acquired the data. The Royal Greenwich Observatory has moved from Hailsham, East Sussex, to Cambridge, as of 1989. Some effort has been made to retain the names of observatories for the western European languages (French, German, Spanish, Portuguese, and Italian), while other suc names have been translated into English. Table III. List of SSN Observers and Submitters _____________________________________________________________________________ Observer/Submitter Institute (City, State, Country) _____________________________________________________________________________ M.F. A'Hearn University of Maryland, College Park, MD, U.S.A. I. Appenzeller Landessternwarte, Heidelberg, F.R.G C. Arpigny Universite de Liege, Cointe-Ougree, Belgium E.S. Barker McDonald Observatory, University of Texas, Austin TX, U.S.A. J.E. Beckman Universidad de La Laguna, Tenerife, Canary Islands, Spain M.J.S. Belton National Optical Astronomy Observatories, Tucson, AZ, U.S.A. J.H. Black University of Arizona, Tucson, AZ, U.S.A. G. Branduardi Roque de los Muchachos Observatory, Canary Islands, Spain M. Brear Roque de los Muchachos Observatory, Canary Islands, Spain M.W. Buie Space Telescope Science Institute, Baltimore, MD, U.S.A. E.M. Burbidge University of California, San Diego, CA, U.S.A. P.S. Butterworth NASA Goddard Space Flight Center, Greenbelt, MD, U.S.A. L. Castinel European Southern Observatory, La Silla, Chile M. Chester Pennsylvania State University, University Park, PA, U.S.A. K.I. Churyumov Kiev State University, Kiev, Goloseevo, U.S.S.R. K.K. Chuvayev Kiev State University, Kiev, Goloseevo, U.S.S.R. K. Chuvaev Crimean Astrophysical Observatory, Nauchny, Crimea, USSR A. Cochran McDonald Observatory, University of Texas, Austin, TX, U.S.A. W.D. Cochran McDonald Observatory, University of Texas, Austin, TX, U.S.A. C. Corbally Steward Observatory, University of Arizona, Tucson, AZ, U.S.A. C. Cosmovici Instituto di Astrofisica Spatiale, Fracasti, Roma, Italy I. Coulson South African Astronomical Observatory, Observatory, South Africa D.P. Cruikshank NASA Ames Research Center, Moffett Field, CA, U.S.A. A. Danks Applied Research Corporation, Landover, MD, U.S.A. M.S. Dementyev Main Astronomical Observatory, Kiev, Goloseevo, U.S.S.R. M. DiSanti University of Arizona, Tucson, AZ, U.S.A. S. Djorgovski California Institute of Technology, Pasadena, CA, U.S.A. A.N. Dovgopol Main Astronomical Observatory, Kiev, Goloseevo, U.S.S.R. T. Encrenaz Observatoire de Paris, Meudon, France L. Engel Arizona State University, Tempe, AZ, U.S.A. A.P. Fairall University of Capetown, Rondebosch, South Africa R. Falciani Osservatorio Astrofisico di Arcetri, Firenze, Italy D. Faria Observatorio Nacinal, Rio de Janeiro, Brazil P.D. Feldman Johns Hopkins University, Baltimore, MD, U.S.A. A.J. Ferro Arizona State University, Tempe, AZ, U.S.A. M. Festou Observatoire de Besancon, Besancon, France A.V. Filippenko University of California, Berkeley, CA, U.S.A. U. Fink University of Arizona, Tucson, AZ, U.S.A. R. Falciani Bologna University Observatory, Loiano, Italy R.F. Garrison David Dunlap Observatory, Richmond Hill, Ontario, Canada R. Gilmozzi Astrophysics Institute, Frascati, Italy R. Goodrich Lick Observatory, Mt. Hamilton, CA, U.S.A. D.I. Gorodetsky Kiev State University, Kiev, Goloseevo, U.S.S.R. J. Green McDonald Observatory, University of Texas, Austin, TX, U.S.A. R. Haefner Universitats Sternwarte, Munchen, F.R.G. D. Harmer Royal Greenwich Observatory, Cambridge, U.K. J. Harland Lick Observatory, University of California, Mt. Hamilton, CA, U.S.A. G.H. Herbig University of Hawaii, Honolulu, HI, U.S.A. S. Ibadov Institute of Astrophysics, Dushanbe, U.S.S.R. W. Jaworski University of Victoria, Victoria, British Columbia, Canada V. Jesipov Institute of Astrophysics, Duschanbe, USSR D. Jewitt University of Hawaii, Honolulu, HI, U.S.A. M. Kane Goddard Space Flight Center, College Park, MD, U.S.A. P. Kelton McDonald Observatory, University of Texas, Austin, TX, U.S.A. M. Kidger Universidad de La Laguna, Tenerife, Canary Islands, Spain D. Kilkenny South African Astronomical Observatory, South Africa V.M. Klimenko Main Astronomical Observatory, Kiev, Goloseevo, U.S.S.R. P.P. Korsun Main Astronomical Observatory, Kiev, Goloseevo, U.S.S.R. S. Koutchmy National Solar Observatory, Sunspot, NM, U.S.A. P.L. Lamy Laboratoire d'Astronomie Spatiale, Marseille, France S.J. Codina- Landaberry Observatorio Nacional, Sao Cristouao, Rio de Janeiro, Brazil R. Las Casas Observatorio Nacional, Sao Cristouao, Rio de Janeiro, Brazil E. Lindholm Arizona State University, Tempe, AZ, U.S.A. T. Lloyd-Evans South African Astronomical Observatory, Observatory, South Africa G. Loper Arizona State University, Tempe, AZ, U.S.A. B.L. Lutz Lowell Observatory, Flagstaff, AZ, U.S.A. P. Mack McGraw-Hill Observatory, c/o NOAO, Tucson, AZ, U.S.A. L. MacFadden University of Maryland, College Park, MD, U.S.A. K. Magee-Sauer University of Delaware, Newark, DE, U.S.A. P. Malburet European Southern Observatory, LA Silla, Chile C. Malivoir Observatoire de Haute-Provence, St. Michel de l'Observatoire, France M. Malkan University of California, Los Angeles, CA. U.S.A. O. Mamadov Institute of Astrophysics, Dushanbe, U.S.S.R. J. Manfroid Universite de Liege, Liege, Belgium F. Marang South African Astronomical Observatory, Observatory, South Africa R. Marcialis Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, U.S.A. R. Martin Royal Greenwich Observatory, Cambridge, U.K. Y. Matsuguchi Okayama Astrophysical Observatory, Japan M. Matsumura Okayama Astrophysical Observatory, Japan P. McCarthy University of California, Berkeley, CA, U.S.A. J.S. Miller Lick Observatory, University of California, Santa Cruz, CA, U.S.A. A. Miyashita National Astronomical Observatory, Mitaka-Shi, Tokyo, Japan Muers Roque de los Muchachos, Canary Islands, Spain P. Murdin Royal Greenwich Observatory, Cambridge, U.K. C. Nitscheim Observatoire de Haute-Provence, St. Michel de l'Observatoire, France C.R. O'Dell Rice University, Houston, TX, U.S.A. R. Oliversen Kitt Peak National Observatory, Tucson, AZ, U.S.A. C. Opal McDonald Observatory, University of Texas, Austin, TX, U.S.A. J. Pacheco Observatorio Ncaional, Rio de Janeiro, Brazil P. Patriarchi Osservatorio Astrofisico di Arcetri, Firenze, Italy B. Peterson Mount Stromlo & Siding Spring Observatories, Canberra, ACT Austral ia M. Prieto Roque de los Muchachos, Canary Islands, Spain D.A. Ramsay National Research Council of Canada, Ottawa, Ontario, Canada L. Ramsey Pennsylvania State University, University Park, PA, U.S.A. N. Reid Roque de los Muchachos, Canary Islands, Spain R.J. Reynolds University of Wisconsin, Madison, WI, U.S.A. F. Roesler University of Wisconsin, Madison, WI, U.S.A. E. Roettger Johns Hopkins University, Baltimore, MD, U.S.A. T. Santos Observatorio Nacional, Rio de Janeiro, Brazil W. Sargent Palomar Observatory, California Institute of Technology, Pasadena, CA, U.S.A. S. Sawyer McDonald Observatory, University of Texas, Austin, TX, U.S.A. F. Scherb University of Wisconsin, Madison, WI, U.S.A. D.G. Schleicher Lowell Observatory, Flagstaff, AZ, U.S.A. A. Schultz Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, U.S.A. V. Shavlovski Main Astronomical Observatory, Kiev, Goloseevo, U.S.S.R. K.R. Sivaraman Indian Institite of Astrophysics, Bangalore, India L.A. Smaldone Dipartimento di Fisica, Napoli, Italy H. Spinrad University of California, Berkeley, CA, U.S.A. M. Strauss University of California, Berkeley, CA, U.S.A. M. Takada-Hadai Tokai University, Hiratsuka-Shi, Kanagawa, Japan H. Tanabe National Astronomical Observatory, Mitaka-Shi, Tokyo, Japa Y. Taniguchi Kiso Observatory, Kiso-Gun, Nagano-Ken, Japan V.P. Tarashchuk Kiev State University, Kiev, Goloseevo, U.S.S.R. J.B. Tatum University of Victoria, Victoria, British Columbia, Canada S. Tegler University of Florida, Gainesville, FL, U.S.A. R. Terlevich Royal Greenwich Observatory, Cambridge, U.K. J. Theobald Arizona State University, Tempe, AZ, U.S.A. G.P. Tozzi Osservatorio Astrofisico di Arcetri, Firenze, Italy S. Unger Royal Greenwich Observatory, Cambridge, U.K. W. van Breugel University of California, Berkeley, CA, U.S.A. C. Vanderriest Observatoire de Paris, Meudon, France R.M. Wagner Lowell Observatory, Flagstaff, AZ, U.S.A. M. Wallis University College Cardiff, Wales, U.K. J. Watanabe Tokyo National Observatory, Tokyo, Japan H. Weaver Space Telescope Science Institute, Baltimore, MD, U.S.A. P.A. Wehinger Arizona State University, Tempe, AZ, U.S.A. M. Womack Arizona State University, Tempe, AZ, U.S.A. T. Woods Johns Hopkins University, Baltimore, CA, U.S.A. Wu Guangjie Yunnan Observatory, Kunming, China S. Wyckoff Arizona State University, Tempe, AZ, U.S.A. F. Wyk South African Astronomical Observatory, Observatory, South Africa Y.S. Yatskiv Main Astronomical Observatory, Kiev, Goloseevo, U.S.S.R. D.K. Yeomans Jet Propulsion Laboratory, Pasadena, CA, U.S.A. J.-M. Zucconi Observatoire de Besancon, Besancon, France _____________________________________________________________________________ Table IV. Contributed Comet Halley Spectra ____________________________________________________________________ Submitter State/Country No. Date Observatory Spectra Received ____________________________________________________________________ Wehinger, P Arizona, USA 13 15 Jun 87 AAT Herbig, G California, USA 134 22 Jun 87 Lick Tatum, J B.C., Canada 222 10 Sep 87 AAT O'Dell, C Texas, USA 35 02 Nov 87 CTIO Spinrad, H California, USA 44 06 Nov 87 Lick Festou, M France 38 09 Nov 87 IUE Tegler, S Arizona, USA 1 30 Nov 87 CTIO Buie, M Hawaii, USA 5 03 Dec 87 MKO Jewitt, D Mass, USA 139 07 Dec 87 KPNO Haefner, R Germany 9 21 Dec 87 ESO Magee, K Wisconsin, USA 383 25 Feb 88 KPNO Appenzeller, I Germany 5 04 Mar 88 ESO Ramsay, D Ontario, Canada 81 15 Mar 88 AAT Takada-Hidai, M Japan 36 05 Apr 88 Okayama Mack, P South Africa 15 06 Apr 88 SAAO Magee, K Wisconsin, USA 96 22 Apr 88 KPNO Tozzi, G-P Italy 39 25 Apr 88 ESO Filippenko, A California, USA 39 25 May 88 Palomar Korsun, P Urkaine, USSR 7 25 May 88 Kiev Garrison, R Ontario, Canada 33 31 May 88 LCO Taniguchi, Y Japan 3 31 May 88 Okayama Koutchmy, S France 2 09 Jun 88 ESO Chester, M Penn, USA 15 21 Jun 88 Penn St Landaberry, S Brazil 12 23 Jun 88 Obs Nat Brazil Cochran, A Texas, USA 558 27 Jun 88 McDonald Cochran, A Texas, USA 76 14 Jul 88 McDonald Tanabe, H Japan 8 03 Aug 88 Tokyo Astr Lamy, P France 14 03 Aug 88 ESO Engel, L Arizona, USA 18 01 Sep 88 KPNO Lindholm, E Arizona, USA 17 01 Sep 88 Mt Stromlo Lindholm, E Arizona, USA 18 07 Sep 88 Mt Stromlo Theobald, J Arizona, USA 13 04 Oct 88 AAT Festou, M France 350 07 Nov 88 IUE Encrenaz, T France 70 07 Nov 88 ESO Sivaraman, K R India 16 22 Nov 88 Bappu Obs Martin, R United Kingdom 116 28 Nov 88 La Palma Peterson, B Australia 60 02 Dec 88 AAT Tegler, S Arizona, USA 7 19 Dec 88 CTIO Kidger, M Spain 48 28 Dec 88 La Palma Belton, M Arizona, USA 19 04 Jan 89 KPNO Feldman, P Maryland, USA 4 04 Jan 89 Rocket Womack, M Arizona, USA 7 30 Jan 89 AAT Wagner, M Arizona, USA 76 06 Feb 89 Lowell Womack, M Arizona, USA 4 20 Feb 89 AAT Festou, M France 152 08 Mar 89 IUE Wehinger, P Arizona, USA 6 09 Mar 89 CTIO Yatskiv, Y Urkaine, USSR 259 14 Mar 89 Kiev Wu, G P.R. China 6 22 Mar 89 Yunnan Zucconi, J-M France 15 28 Mar 89 OHP Festou, M France 264 10 Apr 89 IUE Total 3500 (140% of expected submissions) ____________________________________________________________________ Table V. Worldwide Distribution of Halley Spectroscopic Contributions ____________________________________ Australia Spain Belgium United Kingdom Brazil United States Canada Arizona Chile California China, P.R. Hawaii France Maryland Germany Massachusetts India New Mexico Italy Pennsylvania Japan Texas South Africa Wisconsin Soviet Union ____________________________________ 13. SPECTROSCOPIC SOLAR ATLASES Two high resolution integrated disk solar spectra compiled from a variet of sources are presented in this archive. One was contributed by M. A'Hearn and the other by R. Kurucz. The A'Hearn solar spectrum found in one file, SOLATLS1.FIT, is given in vacuum wavelengths (Angstroms), calibrated in flux units (erg/cm**2/s/A) covering the wavelength range 2245 A to 7000 A in steps of 0.005 A. The Kurucz solar spectrum can be found in two files, SOLATLS2.FI and SOLATLS3.FIT, in air wavelengths (Angstroms), calibrated in flux units (erg/cm**2/s/A). SOLATLS2.FIT covers a wavelength range 2960 A to 8000 A in steps of 0.005 A, SOLATLS3.FIT covers the wavelength range of 8000 A to 13,00 A in steps of 0.01 A. We note a wavelength shift between the two solar spectra presented in this archive of approximately 0.03 A in the sense A'Hear minus Kurucz. We therefore caution users of these files requiring wavelength accuracies better than this difference to first assess and correct the wave- lengths the solar spectra to rest frame. 14. REFERENCES ON COMETARY SPECTROSCOPY Listed below are a few key review papers on cometary physics and spectroscopy that may serve as an introduction for interested observers who are just getting started in the field. These references are simply listed as a guide and a starting point for future investigators. 1. A'Hearn, M.F. 1982. Spectrophotometry of comets at optical wavelengths. In: Wilkening, L.L. (ed.), Comets, Tucson: University of Arizona Press, pp. 433-460. 2. A'Hearn, M.F. 1988. Observations of comet nuclei. Ann. Rev. Earth Planet. Sci. 16, 273-293. 3. Feldman, P.D. 1982. Ultraviolet spectroscopy of comets. In: Wilkening, L.L. (ed.), Comets, Tucson: University of Arizona Press, pp. 461-479. 4. Grewing, M., Praderie, F., and Reinhard, R. (eds.) 1988. Exploration of Halley's Comet, Berlin: Springer, pp. 1-984; see also Astron. Astrophys. 187, 1-936 (1987). 5. Huebner, W.F. 1985. The photochemistry of comets. In: The Photo- chemistry of Atmospheres, Earth, the Other Planets and Comets, New York: Academic Press, pp. 437-508. 6. Krishna Swamy, K.S. 1986. Physics of Comets, Singapore: Worls Scientific Publishing Company. 7. Mendis, D.A. 1988. A post-encounter view of comets. Ann. Rev. Astron. Astrophys. 26, 11-49. 8. Mendis, D.A., Houpis, H.L.F., and Marconi, M.L. 1985. The Physics of Comets. Fundamentals of Cosmic Physics 10, 1-353. 9. Spinrad, H. 1987. Comets and their composition. Ann. Rev. Astron. Astrophys. 25, 231-269. 10. Whipple, F.L., and Huebner, W.F. 1976. Physical Processes in Comets. Ann. Rev. Astron. Astrophys. 14, 143-172. 11. Wyckoff, S. 1982. Overview of comet observations. In: Wilkening, L.L. (ed.), Comets, Tucson: University of Arizona Press, pp.3-55. 12. Wyckoff, S. 1983. Interaction of cometary ices with the Interplanetary Medium. J. Phys. Chem. 87, 4234-4242. 13. Wyckoff, S. 1990. Comets: clues to the early history of the solar system. Earth Sci. Rev., in press. Susan Wyckoff, Anthony J. Ferro, and Peter A. Wehinge Physics-Astronomy Department Arizona State University Tempe, AZ 85281 U.S.A.