------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 862 1994 July 20 19.47UT 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 G N.James, Chelmsford, UK reports visual detection of a large dark spot at the longitude of the impact of fragment G. It crossed the Central Meridian on July 18 at about 20.00UT. The spot looked initially like a shadow transit (although none were in progress) and was visible even at x50 in a 0.075-m refractor. In the 0.30-m reflector x180 it occasionally showed fine structure under good seeing. Fragment H Mark Kidger, Teide Observatory, reports: "Around 19:26UT on 1994 July 18, Fragment H (14) impacted with Jupiter. The Carlos Sanchez Telescope (1.52m infrared telescope) and IAC-80 (an 82cm optical telescope) detected the explosion when it reached the edge of the disc of the planet at 20:07UT. The mark left by the explosion was almost as large as the Great Red Spot, some 20 thousand kilometres in length. Unlike the impact of Fragment A last Saturday, the explosion of Fragment H was immediately visible through a filter tuned to the wavelength of methane gas, when it reached the edge of the disc. The impact zone was immediately visible without having to process the images. The brightness of the visible cloud was clearly superior to that of Fragment A, which is logical given that Fragment H was one of the larger ones in the comet. The night offered a series of thrilling views, such as that of the cloud from Fragment H on the edge of the planet at the same time that the enormous cloud from Fragment G was crossing the centre of the disc. Along with fragment Q, which will impact on Wednesday night, Fragment G is the very largest and has left a mark on the planet which is some 30 thousand kilometres long. This cloud is larger than the Great Red Spot, which could be seen on the disc at the same time. Later, the near simultaneous appearance of the twin spots from impacts E and F left four impact clouds lined up across the face of the planet at the same time." James Lancashire, Cambridge, UK reports his visual observation with the 0.20-m refractor at the University at Cambridge Observatories of the central part of impact site H crossing Jupiter's central meridian on July 18.926UT. Fragment K At Okayama Astrophysical Observatory an initial 2.36-micron flash was detected on July 19.434, followed by an increase on July 19.438 that reached a maximum around 19.443 of perhaps more than 20 times the brightness of Io. M. A'Hearn, University of Maryland, reports that R filter observations at the Perth Observatory during July 19.417-19.437 showed no hint of a flash reflected from Europa, then in eclipse; beginning July 19.441 methane 893-nm filter observations showed a definite prominence above the apparent limb of Jupiter having approximately the same surface brightness as other portions of that latitude belt. IAUC 6028 Guy M Hurst --- 00022 --- Date: Thu, 21 Jul 1994 17:37:29 +1000