Electronic Telegram No. 3439 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network COMET C/2013 E2 (IWAMOTO) Syuichi Nakano, Sumoto, Japan, reports the discovery by Masayuki Iwamoto (Awa, Tokushima-ken, Japan) of a diffuse comet on three 60-s CCD frames taken with a Pentax 100-mm f/4 lens and a Canon EOS 5D digital camera, as follows: 2013 UT R.A. (2000) Decl. Mag. Observer Mar. 10.83377 20 33 - 3 00 13 Iwamoto 11.84324 20 36 - 2 45 13 " Nakano adds that K. Kadota looked closely at Iwamoto's three frames and sees a faint green coma; Nakano measured the three Iwamoto frames, yielding the better astrometric positions tabulated below. Nakano also forwards the astrometry below by Toru Yusa (Osaki, Miyagi-ken, Japan), obtained remotely with a 0.25-m f/3.4 hyperbolic astrograph at the iTelescope Observatory near Mayhill, NM, U.S.A.; Yusa measures a coma diameter of 44" and notes a well-condensed nuclear region. 2013 UT R.A. (2000) Decl. Mag. Observer Mar. 10.83412 20 32 28.19 - 2 58 30.6 14 Iwamoto 11.84359 20 35 59.4 - 2 45 49 " 11.84451 20 35 59.78 - 2 45 53.0 14 " 14.49168 20 45 09.03 - 2 12 26.5 14.5 Yusa 14.49271 20 45 09.24 - 2 12 25.6 " 14.51021 20 45 12.84 - 2 12 12.9 " 14.51123 20 45 13.05 - 2 12 12.1 " 14.51225 20 45 13.24 - 2 12 10.5 " The following preliminary parabolic orbital elements are by G. V. Williams, Minor Planet Center: T = 2013 Mar. 5.5103 TT Peri. = 92.9367 Node = 181.9785 2000.0 q = 1.396249 AU Incl. = 21.9078 The following ephemeris (from the above orbital elements) assumes H_8 = 11.5 for the magnitudes: Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2013 03 09 20 26.02 -03 21.3 1.953 1.397 42.7 28.8 14.1 2013 03 10 20 29.54 -03 08.9 1.953 1.398 42.8 28.9 14.1 2013 03 11 20 33.04 -02 56.4 1.953 1.399 42.8 28.9 14.1 2013 03 12 20 36.53 -02 43.9 1.953 1.399 42.9 28.9 14.1 2013 03 13 20 40.00 -02 31.3 1.953 1.400 43.0 28.9 14.1 2013 03 14 20 43.45 -02 18.6 1.953 1.402 43.0 28.9 14.1 2013 03 15 20 46.89 -02 06.0 1.954 1.403 43.1 29.0 14.1 2013 03 16 20 50.30 -01 53.3 1.954 1.405 43.2 29.0 14.1 2013 03 17 20 53.70 -01 40.6 1.955 1.406 43.2 29.0 14.1 2013 03 18 20 57.08 -01 27.9 1.956 1.408 43.3 29.0 14.1 2013 03 19 21 00.44 -01 15.1 1.956 1.410 43.4 29.0 14.2 2013 03 20 21 03.78 -01 02.4 1.957 1.412 43.5 29.0 14.2 2013 03 21 21 07.11 -00 49.7 1.958 1.414 43.6 29.0 14.2 2013 03 22 21 10.41 -00 36.9 1.960 1.417 43.6 29.0 14.2 2013 03 23 21 13.69 -00 24.2 1.961 1.419 43.7 29.0 14.2 2013 03 24 21 16.95 -00 11.6 1.962 1.422 43.8 29.1 14.2 2013 03 25 21 20.20 +00 01.1 1.963 1.425 43.9 29.1 14.2 2013 03 26 21 23.42 +00 13.7 1.965 1.428 44.0 29.1 14.2 2013 03 27 21 26.62 +00 26.3 1.966 1.431 44.2 29.1 14.2 2013 03 28 21 29.80 +00 38.9 1.968 1.434 44.3 29.1 14.2 2013 03 29 21 32.96 +00 51.4 1.969 1.437 44.4 29.1 14.2 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2013 CBAT 2013 March 14 (CBET 3439) Daniel W. E. Green