------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 856 1994 July 12 17.42UT 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) R. M. West, European Southern Observatory, has measured the nuclei on CCD images obtained during July 1-8 by O. Hainaut, R. Schulz, M. Carollo, C. Alard and A. Cimatti with the 3.5-m New Technology Telescope and 1.5-m Danish telescope. Reductions were with the help of southern Sky Atlas plates and provisional Hipparcos reference-star positions provided by M. Perryman and C. Turon. S. Nakano, Sumoto, Japan, has computed improved orbits and the following times (corrected for light time) for the impacts on Jupiter: A = 21, July 16.826 UT; B = 20, 17.113; C = 19, 17.287; D = 18, 17.483; E = 17, 17.625; F = 16, 18.014; G = 15, 18.308; H = 14, 18.805; K = 12, 19.425; L = 11, 19.919; N = 9, 20.428; P = 8 (= P2 = 8b), 20.624; Q = 7 (= Q1 = 7a), 20.831; R = 6 , 21.223; S = 5, 21.627; T = 4, 21.758; U = 3, 21.907; V = 2, 22.166; W = 1, 22.330. Comparison with computations by P. W. Chodas and D. K. Yeomans, Jet Propulsion Laboratory, suggests that the uncertainty is now around +/- 0.005 day for almost all these nuclei, the remaining uncertainty being mainly because most of the earlier observations were reduced using the STScI Guide Star Catalogue. Using the tidal-disruption model of Z. Sekanina, Chodas and Yeomans provide less certain impact times for lost and less well observed fragments: J = 13, July 19.11 UT; M = 10, 20.24; P1 = 8a, 20.69; Q2 = 7b, 20.81. They add that a significant number of particles beyond the eastern end of the nuclear train should now already have begun to strike Jupiter. IAUC 6017 Guy M Hurst --- 00011 ---