DATA FILE DESCRIPTION
This product represents averaged radiometric diameters and geometric albedos derived from observations made by the Infrared Astronomical Satellite in 1983 for 1796 numbered asteroids and 88 unnumbered asteroids whose orbital elements were determined using astrometry from two or more apparitions.
In the original release of the IMPS data products, a number of of 'asteroid status word (ASTATW)' bits were always set to zero (flag not set) or one (flag set) and have been excluded here, these were:
ASTATW 5 - WSDB MCON position match. All MCON (WSDB 'weeks' or months confirmed) asteroid sightings are rejected by IMPS. These sightings are likely to be confused with stationary background sources (e.g. molecular clouds, galaxies, knots of infrared cirrus). See ASTATW 9. No accepted detections had flag set.
ASTATW 8 - IMPS asteroid association. Set to unity for every accepted asteroid sighting, therefore the flag is always one in this file by definition.
ASTATW 9 - Point Source Ver. 2 match. All asteroid sightings confused with sources in the IRAS Point Source Catalog are rejected by IMPS. This is a subset of ASTATW 5.
ASTATW 10 - Detections only by small detectors on the outer edge of the focal plane array. No accepted detections had this flag set.
ASTATW 11 - Predicted flux < 0.14 Jy. Set a priori for all candidate associations of an IMPS asteroid if no predicted flux density at 25 microns is greater than 0.14 Jansky. No detections were accepted when this flag was set.
ASTATW 16 - 100 micron albedo used in the final average albedo. Since no 100 micron detections contribute to derived IMPS average values, this flag is never set.
ASTATW 17 - Faint Source Version 2 match. All asteroid sightings confused with sources in the IRAS Faint Source Survey are rejected by IMPS (See MOSHIRETAL1992), therefore this flag is always zero in this data file.
ASTATW 20 - Serendipitous Version 1 match. All asteroid sightings confused with sources in the IRAS Serendipitous Survey Catalog are rejected by IMPS (See KLEINMANETAL1986), therefore this flag is always set to zero in this data file.
ASTATW 29 - Not used. Always zero.
ASTATW 31 - 2+ sightings match. Set if more than one source is associated with a single asteroid prediction and therefore rejected by IMPS. No detections were accepted in this file when this flag was set.
ASTATW 32 - Not used. Always zero.
PRODUCT_CREATION_TIME = 1998-03-23 /* Peer Review Date */ ROWS = 1884 COLUMNS = 33 RECORD_FORMAT = "(a5,1x,a18,1x,a9,1x,f5.2,1x,f6.4,1x,f5.3, 1x,f6.2,1x,f4.1,1x,f4.2,1x,i2,1x,i2,1x,f4.2,21(1x,a1))"
ASTEROID ID - The IAU asteroid number designation. For unnumbered asteroids, this field is blank.
ASTEROID NAME - IAU asteroid name. For unnamed asteroids, this field is blank.
ASTEROID PROVISIONAL DESIGNATION - Asteroid principal provisional designation. For named asteroids, this field is blank.
ASSUMED ABSOLUTE MAGNITUDE - Value assumed for absolute visual magnitude H of the asteroid in the derivation of the albedo.
MEAN ALBEDO - The average of geometric albedos derived from assumed values of H and G and each IRAS observation (scaled to zero phase).
MEAN ALBEDO SIGMA - One sigma uncertainty in mean geometric albedo.
EFFECTIVE DIAMETER - Radiometric diameter derived from the mean geometric albedo and the assumed value of H.
EFFECTIVE DIAMETER SIGMA - One sigma uncertainty in effective diameter, set so that its relative uncertainty is half that of the mean geometric albedo.
INTRINSIC VARIATION PROBABILITY - This quantity is used as a measure of the probability that a lightcurve effect is present in the data. Values are constrained to be between 0.1 and 1.0. Less than significant variation is assigned a value of 0.1.
NUMBER SIGHTINGS USED - The number of sightings (detected crossings of the IRAS focal plane) used to derive these results.
NUMBER OBSERVATIONS USED - The number of observations (fluxes) over all detectors averaged to produce these results.
FRACTION OBSERVED RATIO - The ratio of the number of times the asteroid was predicted to cross the IRAS focal plane to the number of crossings detected.
ASTEROID STATUS WORD 01 OR - Low position score. This flag is set to unity when the difference between the predicted and the observed positions for an asteroid's association is deemed significant for any of the accepted sightings.
ASTEROID STATUS WORD 02 OR - ADAS type 1 accept. Set for all sightings of an asteroid with identification number less than 3318 which was accepted in ADAS.
ASTEROID STATUS WORD 03 OR - ADAS type 1 reject. Set for all sightings of an asteroid with identification number less than 3318 which was rejected in ADAS.
ASTEROID STATUS WORD 04 OR - WSDB HCON position match. Set if any of the accepted sightings was hours-confirmed (WSDB reject).
ASTEROID STATUS WORD 06 OR - Small scale Ver. 1 match. Set if any of the accepted sightings indicate resolved spatial structure.
ASTEROID STATUS WORD 07 OR - Relative flux out of bounds. Set if the ratio of observed to predicted flux density at 25 microns is either less than 0.3 or greater than 3.0 for any of the accepted sightings.
ASTEROID STATUS WORD 12 OR - Low detection rate FOR. Set for all sightings of each asteroid if the rate of successful detections, i.e., the fraction observed ratio FOR [(number of sightings used)/(number used plus number missed)], is less than 0.3.
ASTEROID STATUS WORD 13 OR - Set if the 12 micron albedo from any sighting was used in calculating the mean albedo.
ASTEROID STATUS WORD 14 OR - Set if the 25 micron albedo from any sighting was used in calculating the mean albedo.
ASTEROID STATUS WORD 15 OR - Set if the 60 micron albedo from any sighting was used in calculating the men albedo.
ASTEROID STATUS WORD 18 OR - Set when the 25 micron flux of any accepted sighting was less than 1 Jy.
ASTEROID STATUS WORD 19 OR - Large albedo range. Set for all sightings of an accepted asteroid if the ratio {[max - min]/[min + max]/2} is greater than 0.75 for all derived albedos used in the final IMPS average.
ASTEROID STATUS WORD 21 OR - Set if any accepted sighting is within the galactic plane (-10 degrees < Galactic latitude < 10 degrees).
ASTEROID STATUS WORD 22 OR - Galactic center match. Set if any accepted asteroid 25 micron sightings were near the galactic center: +/- 3 degrees latitude by +/- 10 degrees longitude. Subset of asteroid status word 21.
ASTEROID STATUS WORD 23 OR - ADAS type 2 now type 1. Set if provisional asteroid elements updated and numbered since 1985.
ASTEROID STATUS WORD 24 OR - Flux correction used. Set if any accepted sighting flux density was decreased to compensate for IRAS bias near its SNR cutoff.
ASTEROID STATUS WORD 25 OR - 12 micron high density. Set if any accepted sighting is within an IRAS 12 micron High Source Density Region near the galactic center. See asteroid status word 26.
ASTEROID STATUS WORD 26 OR - 25 micron high density. Set if any accepted sighting is within an IRAS 25 micron High Source Density Region near the galactic center. See asteroid status word 25.
ASTEROID STATUS WORD 27 OR - 60 micron high density. Set if any accepted sighting is within an IRAS 60 micron High Source Density Region of low galactic latitude near the center and anti-center.
ASTEROID STATUS WORD 28 OR - 100 micron high density. Set if any accepted sighting is within an IRAS 100 micron High Source Density Region around the galactic center and anti-center.
ASTEROID STATUS WORD 30 OR - 2+ known asteroid match. Set if any accepted sighting is associated with more than one asteroid prediction.