Circular No. 5361 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Telephone 617-495-7244/7440/7444 (for emergency use only) TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505 MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN PERIODIC COMET SHOEMAKER-LEVY 5 (1991z) The following precise positions have been reported: 1991 UT R.A. (1950) Decl. Observer Oct. 5.17350 0 21 16.56 - 7 17 26.7 McCrosky 5.18052 0 21 16.25 - 7 17 24.8 " 5.54896 0 20 58.12 - 7 15 37.5 McNaught R. E. McCrosky and C.-Y. Shao (Oak Ridge). 1.55-m reflector + CCD. R. H. McNaught (Siding Spring). Uppsala Southern Schmidt telescope. The following preliminary orbital elements, from the five available observations, indicate that this is a short-period comet: T = 1991 Dec. 1.533 ET Peri. = 0.430 e = 0.48700 Node = 30.062 1950.0 q = 1.96464 AU Incl. = 11.057 a = 3.82974 AU n = 0.131507 P = 7.49 years 1991 ET R.A. (1950) Decl. Delta r m1 Oct. 1 0 24.71 - 7 34.0 1.040 2.033 16.2 6 0 20.60 - 7 13.7 11 0 16.63 - 6 48.8 1.038 2.013 16.1 16 0 12.98 - 6 19.1 21 0 09.82 - 5 44.6 1.058 1.996 16.1 26 0 07.27 - 5 05.4 31 0 05.44 - 4 21.9 1.099 1.983 16.2 E. Bowell, Lowell Observatory, reports that unflattened R-band CCD frames of 5-min exposure taken by B. A. Skiff on Oct. 5 with the 1.1-m Hall reflector show that the comet exhibits a coma extending only 15" from the nucleus, which is very strongly condensed, most of the light being within 5" of the photocenter (m1 about 16.0-16.5). PERIODIC COMET SHOEMAKER 1 (1991p) Total visual magnitude estimate by C. S. Morris, Lockwood Valley, CA (0.51-m reflector): Oct. 6.18 UT, 14.1. 1991 October 7 Daniel W. E. Green