PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (213) 354-5011
FOR RELEASE
AUG 21, 1982

       An international network of scientists and amateur astronomers is being organized to observe Comet Halley as part of coordinated program when the comet passes Earth in 1986, it was announced today at meeting of the International Astronomical Union in Patras, Greece.

       The organization, called the International Halley Watch (IHW), will be led by Ray Newburn, cometary science team leader at Caltech's Jet Propulsion Laboratory, Pasadena, Calif., U.S.A., and Jurgen Rahe, director of Remeis Observatory (Bamberg) of the University of Erlangen-Nurnberg, Erlangen, Federal Republic of Germany.

       The IHW invites all Comet Halley observers, professional or amateur, to share their data with the IHW networks now being created. Ground-based observations along with those of balloon, airborne and Earth-orbital instruments will be collected by the IHW. Data compiled by the IHW will form the Halley Archive, the largest collection of information ever produced on single comet.

       Japan, the Soviet Union, and the European Space Agency are each sending spacecraft to encounter the comet in 1986, and plan to supply their scientific results to the Halley Archive.

       Experiment teams supported by the IHW will study the comet using seven general techniques:

       * Large-scale phenomena studies will use wide angle photography to study the comet's tails.

       * Near-nucleus studies, using high-resolution photo graphic and electronic imaging of the coma, will yield data on the nucleus, its rotation rate, surface structure, and the comet's general activity.

       * Spectroscopy and spectrophotometry will provide data on the physical composition of the nucleus, coma and tail.

       * Photometry and polarimetry will determine the abundances and distribution of volatile and non-volatile components of the coma and tail.

       * Radio science experiments study the chemical composition and kinematics, or motion, of the coma, nucleus and tail, searching for chemical species not discernable in optical wavelengths. Radio experiments will also detect thermal emissions from solids and perform studies of plasmas.

       * Infrared spectroscopy and radiometry will determine the temperature, size and composition of dust particles released by the comet. Gaseous components may also be identified.

       * Astrometric observations -- studies of Halley's position in relation to stars -- will provide information on the comet's orbit and ephemeris. The observations will also help determine what effect outgassing of ice from the nucleus has on the comet's velocity.

       The efforts of amateur astronomers will be coordinated by the IHW to complement those of professionals:

       * Amateur visual and photographic observations will be compared with those of the l9l0 apparition of Halley.

       * Spectroscopy and photoelectric photometry of the comet obtained by amateurs can provide supplementary coverage of Halley in cases of weather interference at major observatories.

       * Amateur studies of meteors during the Halley apparition will be especially helpful, since few professional astronomers devote time to meteor observations. The Eta Aquarid meteor shower in May 1986 and the Orionid Meteor shower in October in the same year are believed to originate from Halley.

       The IHW office at JPL is funded by NASA, and the Bamberg office is supported by the Federal Republic of Germany.

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8/21/82 MBM
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