Electronic Telegram No. 87 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html COMET P/2004 NL21 (LINEAR) An apparently asteroidal object, designated 2004 NL21 on the basis of LINEAR observations on July 15 and 16 (MPS 110794; discovery observation below), and for which the Minor Planet Center has published several "cometary" orbits (cf. e.g., MPEC 2004-O40, MPO 66393, MPEC 2004-S06), has been reported as of cometary appearance by R. H. McNaught from observations with the 0.5-m Uppsala Schmidt at Siding Spring. Sixty-second CCD exposures on Sept. 6.6 UT showed a near-asteroidal condensation with a narrow fan tail extending about 40" in p.a. 220 deg; on Sept. 18.5 there was a tail about 60" long in p.a. 230 deg. 2004 UT R.A. (2000) Decl. Mag. Observer July 15.34442 23 04 09.89 -14 10 18.4 19.3 LINEAR The Siding Spring astrometry and other recent observations not already published in the MPS, together with the latest equinox 2000.0 orbital elements (T = 2004 Oct. 13, Peri. = 18 deg, Node = 337 deg, i = 17 deg, q = 2.08 AU, P = 7.9 years), residuals and an ephemeris are given on MPEC 2004-S17. NOTE: These 'Central Bureau Electronic Telegrams' are intended to be preliminary announcements of items that later appear in the formal IAU Circulars. Citations should normally be made to IAUCs rather than to CBETs. (C) Copyright 2004 CBAT 2004 September 18 (CBET 87) Brian G. Marsden