Data Set Overview : In preparation for the concerted international study of Comet Halley, the IHW conducted a trial run with observations of Comet Crommelin, largely during February and March of 1984.  Data were acquired by eight disciplines, distinguished by the observing techniques they used, namely:  (1) Astrometry, (2) Infrared studies, (3) Large-scale phenomena (wide angle photography), (4) Near-nucleus studies (high resolution imaging), (5) Photometry and polarimetry, (6) Radio studies, (7) Spectroscopy and spectrophotometry, and (8) Amateur studies.   Data : The IHW data set comprises several 'tables' of results based on analysis of each of the following data types:  (1) EDR - Experiment Data Record (2) DIDR - Digitalized Image Data Record (3) RDR - Reduced Data Record (4) NDR - NO-DATA Data Record  The observations were formatted by Discipline Specialists in each area, checked, and transmitted to the Lead Center for publication and mutual evaluation. Data were machine processed to the extent possible to avoid the introduction of human errors. These data were presented in printed format in JPL Publication 86-2, dated Dec 15, 1985, and were included, with limited indexing, by the Planetary Data System organization on a test CD-ROM in 1988 (Space Science Sampler, Volume 2; PDS Interactive Data Interchange).   Data Coverage and Quality : The Crommelin archive contains about 45 Mbytes of data in 687 files, not counting supporting information, etc. These data do not have the sophisticated headers of the GZ and Halley data that permit easy manipulation and detailed database searches, but the IHW felt it was useful to make them more widely available to the cometary research community, so they are included on this 'GZ' disc.

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