Circular No. 5397 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 7 (1991d1) The following additional positions have been reported: 1991 UT R.A. (1950) Decl. m1 Observer Nov. 28.50139 3 25 12.83 +42 32 07.5 17 Seki 28.63888 3 25 10.67 +42 30 48.3 " Dec. 5.15394 3 24 43.69 +41 22 19.1 McCrosky 5.17341 3 24 43.55 +41 22 06.7 " T. Seki (Geisei). Communicated by S. Nakano. R. E. McCrosky (Oak Ridge). 1.55-m reflector + CCD. Orbital elements by B. G. Marsden, Harvard-Smithsonian Center for Astrophysics, from seven observations, Nov. 13-Dec. 5: T = 1991 Oct. 27.3096 ET Peri. = 91.7535 e = 0.542469 Node = 312.3191 1950.0 q = 1.628858 AU Incl. = 10.2625 a = 3.560102 AU n = 0.1467271 P = 6.717 years 1991 ET R.A. (1950) Decl. Delta r m1 Nov. 30 3 25.00 +42 17.5 0.712 1.663 16.6 Dec. 5 3 24.73 +41 24.1 10 3 25.21 +40 24.9 0.747 1.685 16.8 15 3 26.56 +39 22.3 20 3 28.80 +38 18.5 0.801 1.713 17.0 25 3 31.93 +37 15.3 30 3 35.89 +36 14.1 0.872 1.745 17.3 PERIODIC COMET SHOEMAKER-LEVY 6 (1991b1) Total visual magnitude estimates (cf. IAUC 5386): Nov. 14.29 UT, 11.4 (A. Hale, Tucumcari, NM, 0.20-m reflector); 25.11, 11.8 (Hale, Las Cruces, NM, 0.41-m reflector); 29.98, 12.4 (A. Boattini, Monte Morello, Italy, 0.20-m reflector); Dec. 3.85, 12.8 (H. Mikuz, Ljubljana, Yugoslavia, 0.20-m reflector). 1991 December 5 Daniel W. E. Green