Circular No. 5344 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 1991 RB Further precise positions have been reported as follows: 1991 UT R.A. (1950) Decl. Observer Sept. 8.58380 21 21 57.59 -65 51 08.5 McNaught 10.35627 20 49 17.51 -66 01 17.3 Gilmore 10.38370 20 48 43.59 -66 01 16.9 " R. H. McNaught (Siding Spring). Uppsala Schmidt. Faint image. A. C. Gilmore and P. M. Kilmartin (Mt. John Observatory). Revised elements from observations on Sept. 4, 6.616, 8 and 10: T = 1991 Nov. 9.278 ET Peri. = 68.418 e = 0.52448 Node = 358.536 1950.0 q = 0.73614 AU Incl. = 20.896 a = 1.54807 AU n = 0.511702 P = 1.93 years 1991 ET R.A. (1950) Decl. Delta r V Sept.11 20 36.20 -65 57.1 0.163 1.082 17.3 16 18 42.93 -61 48.5 21 17 02.89 -48 46.7 0.111 0.997 17.4 26 15 56.31 -28 05.9 Oct. 1 15 13.43 - 7 27.2 0.118 0.917 20.2 PERIODIC COMET GRIGG-SKJELLERUP S. Roeser, Astronomisches Rechen-Institut, Heidelberg, advises us that he and U. Bastian are preparing a special star catalogue for use in making observations of this comet in connection with the Giotto encounter next year. The first part, consisting of an extract from the PPM and Fokat catalogues (but using equinox B1950.0) with stars extending 1 deg on each side of the comet's ephemeris during Nov. 1991-July 1992, will be available from the European Space Operations Centre (ESOC), Robert-Bosch Strasse 5, W-6100 Darmstadt, Germany, around Oct. 1. For the most critical time (1992 May 1 to early July) some 1000 additional reference stars of mv about 12 within 15 arcmin of the ephemeris are being selected from the GSC and AC in order to give a density of 35 stars/deg**2. Positions of these stars will be accurately observed with the Carlsberg Meridian Circle on La Palma later this year. This part of the catalogue should be available next March. 1991 September 12 (5344) Brian G. Marsden
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