PDS_VERSION_ID                    = PDS3
RECORD_TYPE                       = STREAM
LABEL_REVISION_NOTE               = "NULL"

OBJECT                            = INSTRUMENT
  INSTRUMENT_HOST_ID              = "AMON"
  INSTRUMENT_ID                   = "AMPG"

  OBJECT                          = INSTRUMENT_INFORMATION
    INSTRUMENT_NAME               = "AMATEUR PHOTOGRAPHY"
    INSTRUMENT_TYPE               = "CAMERA"
    INSTRUMENT_DESC               = "

    Instrument Overview
    ===================
    Amateur observations of periodic Comet Halley commenced with
    the visual recovery of the comet by S. J. O'Meara on 1985
    January 23. They ended with D.H. Levy's observation on 1988
    February 23. Within that period 11641 magnitudes and other
    related visual estimates were made. 2170 photographs span
    1985 August 12 to 1988 February 16. Observations from 637
    amateur astronomers were used in the archive.
 
        The observations, compiled by the Discipline Specialist
    Team, can be grouped into two distinct categories:
 
        (1) Visual-appearance descriptions.
        (2) Photographs.
 
        Because of the subjective nature of visual-appearance
    observation methods there is diversity in the type and
    quality of information recorded in the archive. When a range
    of values was given by the observer the more conservative
    value was adopted, i.e. a shorter tail, more diffuse
    condensation, smaller coma, and fainter magnitude.
 
        All the photographic images listed are on file and were
    examined for quality before inclusion in the archive
    listings.
 
 
    Scientific Objectives
    =====================
         In the archive, telescopes used for photography
    commonly have the focal length, focal ratio, and aperture
    all specified. When camera lenses were used, only the
    focal length and focal ratio are listed. The focal ratio
    listed for a camera lens is that used for the photograph.
 
       Auxiliary lenses are sometimes used on telescopes and
    cameras to change the focal length. When reimaging is not
    involved and a negative lens is used to increase the
    telescope's effective focal length, these lenses are
    commonly called telextenders (or Barlow's when used
    visually). A telecompressor shortens the effective focal
    length without reimaging.
 
       The ISO speed of the emulsion is given as supplied by the
    observer or manufacturer. Some emulsions do not have a speed
    determined and in some cases the film has been
    push-processed beyond published limits.
 
       Kodak developer D-19b is commonly used by European
    astrophotographers. It is an X-ray emulsion developer that
    is radically different in composition from its high-contrast
    American namesake, D-19. Contact Eastman Kodak Co. for
    details. Kodak can also provide details on the spectral
    transmission of its gelatin Wratten filter series; many of
    these designation numbers have been adopted for equivalent
    glass filters made by other manufacturers.
 
       While there are some originals in the archive, the
    archive largely lists copies of one of the following type:
    Contact Prints, Negatives, Prints, Slides, and
    Transparencies. The data files contain hardcopy images
    ranging in size from 135-size images to oversize prints."

  END_OBJECT                      = INSTRUMENT_INFORMATION

  OBJECT                          = INSTRUMENT_REFERENCE_INFO
    REFERENCE_KEY_ID              = "JPL D-400-450"
  END_OBJECT                      = INSTRUMENT_REFERENCE_INFO
END_OBJECT                        = INSTRUMENT
END