PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
FOR IMMEDIATE RELEASE

       A new survey of comets and asteroids, described by scientists as the most comprehensive ever, was carried out by the Infrared Astronomical Satellite (IRAS). The information was reported during the current annual fall meeting of the American Geophysical Union, in San Francisco.

       The survey, the largest, most uniform and least biased ever made of asteroids and comets, was conducted by scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The team, led by JPL scientist Dr. Dennis L. Matson, included Drs. Glenn J. Veeder and Edward F. Tedesco, also of JPL; Dr. L.A. Lebofsky, Lunar and Planetary Laboratory, University of Arizona, Tucson and Russell G. Walker, Jamieson Science and Engineering, Inc., Felton Calif.

       A total of 11,499 sightings of known asteroids was made. Ultimately, 7,015 of the sightings met the high reliability and other requirements of the asteroid catalog and are listed.

       For the comets, there were 384 sightings of which 131 met the catalog acceptance requirements. The data correspond to 22 individual comets.

       According to Matson, "IRAS scanned about 96 percent of the sky through four infrared regions of the spectrum.

       The large number of object sightings provided excellent sampling of the spatial distributions of the objects. The instrument and survey parameters were relatively constant throughout, yielding uniform set of data."

       This was the first survey to observe thermal emissions and thereby avoided the severe albedo, or reflection, bias present in visual surveys.

       IRAS, joint project of the United States, The Netherlands and the United Kingdom, was launched Jan. 25, 1983, from the Western Test Range in California.

       Matson and his colleagues presented various plots and tables which show the characteristics of the survey data. The data provide new basis upon which to assess the location and potential amount of these primitive bodies in the solar system.

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12/8/86 JD
#1113