| DATA_SET_DESCRIPTION |
Data Set Overview
=================
The data presented with this data set include:
1) SIGHTING.TAB - contains a listing of 8210 individual sightings
associated with 2004 asteroids. SIGHTING.TAB contains the
observation index, the identification of asteroids sighted,
information pertaining to observation times, positional information
on the observations of asteroids detected, geometric albedos,
diameters and their associated uncertainties, input values used in
the calculations of the geometric albedos and diameters using the
asteroid standard thermal model, the observed flux densities in
each band, detector crossing information, correlation coefficients,
and status flags for reduction steps.
2) DIAMALB.TAB - contains averaged radiometric diameters and
geometric albedos derived from individual observations for 1796
numbered asteroids and 88 unnumbered asteroids (as of 1983) whose
orbital elements were determined using astrometry from two or more
apparitions.
3) SINGLE.TAB - contains an entry for each of 120 asteroids for
which there is an accepted sighting, but in one band only. This
file includes the absolute visual magnitude of the asteroid, the
albedo and diameter derived from the measurement and their
associated uncertainties, and the accepted status word.
4) GRNDDAT.TAB - contains entries for each of 4677 numbered
asteroids and 2632 unnumbered asteroids (as of 1985) for which
associations were sought in the IRAS data. Asteroids 719 Albert
and 878 Mildred were still lost as of 1985 and are not included.
These entries include an initial estimate of geometric albedo and
diameter used in processing IRAS survey observations of asteroids,
the adopted taxonomic classification, and the orbital elements at
three epochs. The Julian dates of the epochs are 2445400.5,
2445500.5, and 2445600.5. For further information regarding these
data see Tedesco, et. al., 1992 [TEDESCOETAL1992].
5) IMPSSTAT.TAB - contains a summary of the number of times each
asteroid was predicted to be scanned, and possible reasons for any
failure to be detected. It contains entries for each of 4677
numbered asteroids and 2632 unnumbered asteroids (as of 1985) for
which associations were sought in the IRAS data. Asteroids 719
Albert and 878 Mildred were still lost as of 1985 and are not
included. These entries include the number of predicted sightings,
number of accepted sightings, number of rejected sightings, number
of missed predicted sightings, number of missed predicted faint
sightings, number of dead 25 micron detector non-detections, number
of noisy 25 micron detector non-detections, number of missed
predictions in the galactic center region, and other
non-detections.
6) REJECT.TAB - summarizes the number of rejected sightings for
each asteroid and possible reasons for rejection.
7) MISSED.TAB - contains a summary of those asteroids which were
predicted to pass across the IRAS focal plane during survey mode,
but which generated no accepted associations. Entries include the
number of times an asteroid was predicted to be scanned but was
missed, and the derived greatest lower limit on the albedo and
least upper limit on the diameter, plus a status word detailing the
circumstances of the observation failure.
8) STMODEL.TAB - contains the flux look-up table used to generate the
IMPS albedos. This table was provided by L. Lebofsky and was
derived from the IRAS standard thermal model.
Modification History
--------------------
The IMPS data set was ingested in 1994 and updated to correct a minor
error in 1995. These versions included only FP102, the diameters and
albedos. The data set has now been updated to include FP103, FP104,
FP105, FP 106, FP107, FP108, and the flux lookup table used tto
generate the IMPS albedos.
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