------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 860 1994 July 18 20.30UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England. Telephone/FAX(0256)471074 Int:+44256471074 INTERNET: GMH at AST.STAR.RL.AC.UK or GMH at GXVG.AST.CAM.AC.UK ------------------------------------------------------------------- PERIODIC COMET SHOEMAKER-LEVY 9 (1993e)/COLLISION WITH JUPITER Fragment C The SL9 message centre relays that an impact associated with fragment C = 19 was detected by P. McGregor and M. Allen at 2.34 microns using the CASPIR infrared camera on the Australian National University 2.3-m telescope and by D. Crisp, V. Meadows, S. Lumsden and S. Lee using IRIS on the 3.9-m Anglo-Australian Telescope at Siding Spring. The event, seen at the limb on July 17.306 UT, brightened appreciably during the first 5 min and was still visible after one hour. A weaker event on July 17.267 has been identified by M. Brown as a probable recurrence of impact A after one Jupiter rotation. The NASA/IRTF Comet Collision Science Team reports that NSFCAM 2.248-micron observations beginning on July 17.285 UT did not record any obvious flash on Io and Europa, but the data are yet to be photometrically reduced. On July 17.302 both the remnant of the A impact (with a surface brightness similar to that of the south polar hood) and a dim spot from fragment C were detected. By July 17.304 site C was considerably brighter than site A, but by July 17.311 site C had faded to about site A's brightness, and it continued to fade until about July 17.319. IAUC 6024 John Rogers, British Astronomical Association, reports his visual detection (before sunset using yellow and polaroid filters) with the 0.30-m refractor at the University of Cambridge of conspicuous dark spots at the predicted impact sites of fragments A and C. Site A, which has clearly grown since the first Hubble image, was the darker (similar to the NEB) and remained visible until it approached Jupiter's limb on July 17.851 UT. Site C was on the central meridian on July 17.828 +/- 0.002. IAUC 6025 Fragment D J. Watanabe and others report the appearance of the plume of fragment D on July 17.501 UT in 2.36-micron images obtained with the 1.88-m telescope at the Okayama Astrophysical Observatory. It was fainter than the plume recorded from the impact of C on July 17.303; that plume was brightest around July 17.306, and the decay phase was observed over one hour. IAUC 6025 Fragment E The French-Swedish-Spanish Nordic Optical Telescope team reports that the impact of fragment E was recorded at 10 microns around July 17.637 UT. It was fainter than impact A seen yesterday. The Calar Alto Observing Team (cf. IAUC 6023) reports the detection of the fireball from fragment E with the 3.5-m Calar Alto telescope in the 2.3-micron band. The event was first noted on July 17.637 UT, and it rapidly increased to more than 30 times the brightness of Europa. By July 17.641 the fireball had dimmed to less than Europa's brightness. On July 17.768 three spots were visible--a bright one (impact E) just past the central meridian, a fainter one (impact A) approaching the central meridian and the faintest one (impact C) just coming over the east limb. At 2.3 microns the brightest spot was 15-20 times fainter than Io, and the others were fainter by further factors of about 1.5 and 2.2. IAUC 6025 Guy M Hurst --- 00020 --- Date: Tue, 19 Jul 1994 22:50:48 +0100 (BST)