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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