***** File FITS_IHW.TXT FITS Format Information All data were submitted to the International Halley Watch Lead Center on magnetic tape, written in FITS or ascii format. There are three primary references to basic FITS (Wells et al, 1981) and its extensions (Greisen and Harten, 1981, Harten et al, 1988). Although commonly viewed as a magnetic tape format, the actual FITS specifications can be interpreted to describe a general byte stream. As such, FITS files may be written on any storage medium, including CD-ROM. Note that there is no inherent record structure called for in the FITS agreements, only a blocking structure for block oriented media such as magnetic tape. The basic FITS agreements call for only a few required keywords (SIMPLE, BITPIX, NAXIS, END must be present; EXTEND may appear; keywords NAXIS1, ..., NAXISn appear as defined by the value of NAXIS). We have also followed recommended conventions for the representation of values of keywords (dates in the format 'dd/mm/yy', SI units used where possible, etc.). The IHW has defined an additional set of mandatory keywords for all submissions to the Lead Center. These are presented in the table below: OBJECT - Name of the object in the data file, a text string. FILE-NUM - Unique 6-digit number of the file submitted to the Lead Center. The first digit identifies the discipline, the other digits are assigned by the individual Disciplines, but must uniquely identify the file. DATE-OBS - UT Date of mid-observation, in the format 'dd/mm/yy'. TIME-OBS - UT Time of mid-observation, as fractional day. DATE-REL - IHW internal release date for data, as date string. DISCIPLN - Name of the network submitting the file, a text string. LONG-OBS - Longitude of the submitting observatory, in the format 'ddd/mm/ss', with degrees from 0 to 360, increasing in the eastward sense. LAT--OBS - Latitude of the submitting observatory, in the format 'sdd/mm/ss'. SYSTEM - An 8-digit coded character string identifying the Discipline, observatory and instrument which supplied the data. The first character identifies the network, the next three identify the observatory (by IAU code number, where one is assigned, 500 otherwise). The next four digits either identify the telescope/instrument combination (if there is an IAU number for the observatory) or the country and observatory (if no IAU number). OBSERVER - Name of the observer(s) who took the data, a text string. The notation "ET AL." indicates that there were more than two observers, and the names of the additional observers are given in a COMMENT later in the header, with the subkeyword "ADD. OBS." SUBMITTR - Name of the person submitting the data to the Lead Center, a text string. SPEC-EVT - A logical value indicating that the observation is a special event. Either T or F. DAT-FORM - A character string defining the form of the data, e.g., 'ASCII', 'NODATA'. REFERENCES Greisen, E. W. and Harten, R. H.: 1981, Astron. Astrophys. Suppl. Ser. 44, 371. Harten, R. H., Grosbol, P., Greisen, E. W. and Wells, D. C.: 1988, Astron. Astrophys. Suppl. Ser. 73, 365. Wells, D. C., Greisen, E. W. and Harten, R. H.: 1981, Astron. Astrophys. Suppl. Ser. 44, 363.