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4.8 micron 10.74 micron

17.4 micron 20.6 micron

MIRAC2 Images of Jupiter at the Time of Galileo Probe Entry

These images of the heat radiation from Jupiter were obtained at the NASA Infrared Telescope Facility (IRTF) during the period Dec. 7 UT 22:06 to 23:18 covering the Galileo probe entry time of 22:57. The 4.8 micron image shows the cloud structure with holes in the clouds appearing bright because of increasing temperature with depth in the Jupiter atmosphere. The image at 10.74 microns is sensitive to ammonia gas abundance and those at 17.4 microns and 20.6 microns to tropospheric temperature. The images all show Jupiter's bands. All but the 20.6 micron image show the longitudinal wave structure. On the 4.8 micron image the probe site is at the lower edge of the upper (North) equatorial band 2/3 of the way from the center to the right (West) limb.

These observations were part of a special daytime observing program carried out Dec 1-10 with the IRTF's NSFCAM at 5 microns and the guest instrument MIRAC2 at 4.8, 7.95, 8.57, 10.74, 13.3, 17.0, 17.4, and 20.6 microns. The telescope primary mirror was covered with a sheet of white polypropylene to protect it from direct radiation from the sun, which was 8 degrees from Jupiter during this period. This resulted in a reduction of signal-to-noise of a factor of 20 at 4.8 microns and 4 at 20 microns.

The observing was done by Jim Friedson, Jay Goguen, Glenn Orton, Sarah Stewart, and Padma Yanamandra-Fisher (JPL), John Spencer (Lowell Observatory), Bill Hoffmann (Steward Observatory), and Bill Golisch (telescope operator, IRTF), with support from Joseph Hora at the Institute for Astronomy and Joe Spitale and Jose Ortiz at JPL.

MIRAC2 was built by the Steward Observatory, University of Arizona, and Smithsonian Astrophysical Observatory, with support from NASA, NSF, Steward Observatory, and Smithsonian Astrophysical Observatory. It is operated by Bill Hoffmann, Giovanni Fazio, Joseph Hora, and Lynne Deutsch.

December 12, 1995