Electronic Telegram No. 5484 Central Bureau for Astronomical Telegrams Mailing address: 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/2015 K7 [Editor's note: this text replaces that on CBET 5482 (discovery information).] Seitaro Urakawa, Japan Spaceguard Association and the leader of the Japanese citizen-science "Small Solar System Bodies Search Project" (COIAS) reports the discovery of a comet on images acquired with the Subaru 8.2-m telescope at Mauna Kea. On 2024 Nov. 26, COIAS member A. Yamauchi contacted Urakawa to report that cometary activity was found for an object visible in images from 2015 May 17 and 21; at that time, Yamauchi reported the astrometry to the Minor Planet Center. Urakawa contacted P. Veres (MPC) on Dec. 11 to report their verification of cometary appearance in the images from 2015 May 17, 21, and 26. 2015 UT R.A. (2000) Decl. Mag. May 17.40688 14 43 08.79 - 1 21 19.1 23.4 17.46303 14 43 07.08 - 1 21 09.8 23.3 17.47151 14 43 06.78 - 1 21 08.1 23.4 17.48635 14 43 06.36 - 1 21 05.9 23.5 17.49695 14 43 06.02 - 1 21 04.2 23.3 21.37537 14 41 10.62 - 1 10 53.6 22.9 21.39295 14 41 10.10 - 1 10 50.9 22.8 21.40102 14 41 09.84 - 1 10 49.5 23.1 21.40910 14 41 09.60 - 1 10 48.3 23.1 23.41231 14 40 10.91 - 1 05 45.8 23.42708 14 40 10.47 - 1 05 43.7 26.31072 14 38 47.31 - 0 58 43.7 23.9 26.32544 14 38 46.88 - 0 58 41.9 23.8 26.32836 14 38 46.83 - 0 58 41.6 23.4 After posting on the MPC's PCCP webpage, S. Deen (Simi Valley, CA, USA) reported that this object was found in publicly available CCD images obtained on 2013 Mar. 9.37 UT with the 4-m reflector (+ DECam) at Cerro Tololo Interamerican Observatory in 0".9 seeing, showing only an apparently stellar object with no clear tail; DECam images taken in similar conditions on 2013 May 6.19 show a very condensed 1".0 coma and no clear tail. Deen notes that a single r-band CCD image taken by B. Gladman with the 3.6-m Canada-France- Hawaii Telescope at Kitt Peak on 2014 Feb. 28.56 in 0".6 seeing shows the comet to be generally stellar but with a possible elongation toward p.a. 125 degrees; a similar exposure taken on 2014 Mar. 6.60 shows a very condensed 0".7 coma with a 2" tail toward p.a. 115 degrees, and another similar exposure on 2014 Mar. 7.57 shows a very condensed 0".7 coma of mag 23.2 with a 1".5 tail toward p.a. 125 degrees. Deen then found that Subaru exposures taken on 2015 Mar. 23.4 in 0".5-0".7 seeing show an appparently stellar coma but a 5"-long tail in p.a. 125 degrees. After the comet was posted on the Minor Planet Center's PCCP webpage, R. Weryk (Department of Physics and Astronomy, University of Western Ontario) reported that he identified pre-discovery images of the comet in photos obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala from 2015 Mar. 28, 29, Apr. 20, and 21 (mag 21.8-24.0), noting that the object was too faint to tell if there was any cometary activity. Additional astrometry appears on MPEC 2024-Y66. The following orbital elements by S. Nakano (Central Bureau) are from 59 observations spanning 2013 Mar. 9-2015 May 26 (mean residual 0".3), with corresponding "original" and "future" values of 1/a being +0.000067 and +0.000139 (+/- 0.000003) AU**-1, respectively. The comet passed 1.26 AU from Saturn on 2014 June 27 UT. Epoch = 2013 Mar. 9.0 TT T = 2013 Feb. 20.05234 TT Peri. = 5.10314 e = 1.0044148 Node = 257.93551 2000.0 q = 9.9404565 AU Incl. = 159.89050 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 December 26 (CBET 5484) Daniel W. E. Green