------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 3129 2015 Dec 19 16.47UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074 INTERNET: GUY@TAHQ.DEMON.CO.UK Backup: gmh@wdcc1.bnsc.rl.ac.uk WORLD WIDE WEB http://www.theastronomer.org ------------------------------------------------------------------- COMET C/2015 X7 (ATLAS) Larry Denneau, on behalf of the "Asteroid Terrestrial-impact Last Alert System" (ATLAS) Team, reports the discovery of a slightly diffuse comet with the new ATLAS 0.5-m f/2.0 Schmidt telescope at Haleakala from nine wide-band "orange" (r + i bands) CCD exposures taken on Dec. 12 and 13 (discovery observations tabulated below). The ATLAS Team obtained confirming images on Dec. 17 with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea by (queue observer D. Woodworth) that show the comet to have a small coma with a short tail at p.a. 30 deg and a longer, fainter tail extending for about 1' in p.a. approximately 110 deg. 2015 UT R.A. (2000) Decl. Mag. Dec. 12.46909 7 10 04.33 -29 38 58.6 17.6 12.52884 7 10 02.54 -29 38 52.5 17.5 13.48565 7 09 34.45 -29 37 24.5 17.4 13.53470 7 09 32.79 -29 37 18.6 17.2 Following a posting on NEOCP and PCCP webpages, L. Buzzi (Varese, Italy) reports his stacked CCD exposures of Dec. 17.04-17.05 UT with a 0.60-m f/4.6 reflector at low altitude shows a condensed coma 10" in size with no clear tail visible in the crowded star field; he measured red magnitude 18.0. Gareth Williams, Minor Planet Centre reports on MPEC 2015-Y18: T 2016 July 30.22018 TT MPCW q 3.6941388 (2000.0) P Q Peri. 348.33293 -0.67913428 -0.49272503 Node 139.88421 +0.72289070 -0.57752632 e 1.0 Incl. 57.60466 +0.12730146 +0.65091120 Ephemeris: Date TT R. A. (2000) Decl. Delta r Elong. m1 2015 12 18 07 07 12.9 -29 27 29 3.5769 4.1974 123.2 18.0 2015 12 24 07 03 46.6 -29 06 34 3.5216 4.1730 125.7 17.9 2016 01 01 06 58 48.9 -28 24 05 3.4584 4.1411 128.4 17.9 2016 01 16 06 49 14.9 -26 17 49 3.3760 4.0838 130.5 17.8 THE ASTRONOMER, 2015 DECEMBER PAPER EDITION The paper magazines for the December edition were posted by Anne Hurst to catch Saturday (Dec 19) morning's post which is the deadline for the delivery of second class UK post by Christmas. We hope this action results in UK subscribers receive their copies by post on time for Christmas. We would like to wish all our TA E-Circular subscribers a very happy Christmas and enjoyable 2016. Guy M Hurst