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Circular No. 8954 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Mailstop 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://www.cfa.harvard.edu/iau/cbat.html ISSN 0081-0304 Phone 617-495-7440/7244/7444 (for emergency use only) COMET C/2008 L3 (HILL) R. E. Hill reports his discovery of another comet on CCD images taken with the 0.68-m Catalina Schmidt telescope (discovery observation tabulated below), the co-added images from the discovery night showing a diffuse coma of diameter about 10"-12" and a diffuse, fan-shaped tail 1'-2' long in p.a. 100 deg; additional co-added images from June 14.2 UT show a poorly defined diffuse nuclear region, a coma diameter of 8"-10", and a broad tail fan about 2' long in p.a. 110 deg. Following posting on the Minor Planet Center's 'NEOCP' webpage, several other CCD astrometrists have reported cometary appearance. J. E. McGaha (Tucson, AZ, U.S.A., 0.36-m reflector) writes that his stacked images from June 13.4 UT show a round 20" coma without condensation and an apparent ill- defined 45" elongation in p.a. 150 deg; his stacked images from June 14.2 show a round 30" coma without condensation. R. Ligustri (Talmassons, Udine, Italy, 0.35-m reflector, June 13.9) notes that stacked images show a 30" coma elongated in p.a. 119 deg. M. Pietschnig (Vienna, Austria, 0.35-m reflector, June 13.9) finds the comet diffuse with a 10" coma, a bright knot 5" from the coma's center in p.a. 117 deg, and a tail about 30" long in p.a. 120 deg. G. Hug (Eskridge, KS, U.S.A., 0.7-m reflector, June 14.14-14.15) detects a short, diffuse tail in p.a. about 100 deg. P. Birtwhistle (Great Shefford, Berkshire, England, 0.40-m reflector, June 15.0) reports a diffuse, poorly condensed coma of diameter 10" in poor seeing. 2008 UT R.A. (2000) Decl. Mag. June 13.27522 13 50 13.13 +58 24 51.1 18.9 The available astrometry, the following preliminary parabolic orbital elements, and an ephemeris appear on MPEC 2008-L56. T = 2008 Apr. 20.148 TT Peri. = 100.558 Node = 23.885 2000.0 q = 2.00238 AU Incl. = 100.404 COMET C/2008 A1 (McNAUGHT) Visual total-magnitude and coma-diameter estimates: Apr. 11.96 UT, 12.2, 2' (M. Goiato, Aracatuba, Brazil, 22-cm reflector; moonlight); 24.94, 11.6, 4' (Goiato); May 5.40, 11.8, 2' (D. A. J. Seargent, Cowra, NSW, Australia, 25-cm reflector); 7.44, 11.4, 2' (Seargent); 11.93, 10.8, 4' (Goiato; moonlight); 25.92, 10.3, 5' (Goiato); June 6.92, 9.9, 5' (Goiato). (C) Copyright 2008 CBAT 2008 June 15 (8954) Daniel W. E. Green
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