Electronic Telegram No. 5581 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/2024 XK_14 (BOK) An apparently asteroidal object discovered on 2024 Dec. 3 with the 2.25-m Bok reflector at Kitt Peak (discovery observations tabulated below) has been found to show cometary appearance elsewhere. It was given the minor-planet designation 2024 XK_14 when announced on MPEC 2024-X264 (also MPS 2292994). 2024 UT R.A. (2000) Decl. Mag. Dec. 3.24864 3 20 00.10 +17 11 15.4 22.6 3.25426 3 19 59.30 +17 11 04.6 22.5 3.25985 3 19 58.51 +17 10 53.9 22.4 3.26546 3 19 57.69 +17 10 43.3 22.2 At the time this was first published (2024 Dec. 9), pre-discovery observations had already been reported from the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala, Hawaii, on 2024 Nov. 28 (mag 22.4-22.5). Additional astrometry appears on MPEC 2025-N87. M. Mattiazzo, Swan Hill, Australia, observed this centaur-type object on 2025 May 31.41 UT with a 0.25-m f/3.8 ASAN reflector located in Rio Hurtado Valley, Chile; eight 60-s stacked CMOS exposures show a possible coma 10" wide (total V mag 17.8) and a possible 25"-long tail in p.a. 145 degrees. Eight stacked 60-s CMOS exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) with a 0.25-m f/3.8 astrograph located at Rio Hurtado on June 9.43 show a strongly condensed coma 12" in diameter and no tail; the magnitude was 17.9 as measured within a circular aperture of radius 7".0. A. Hale (Cloudcroft, NM, USA) writes that individual 300-s CCD exposures taken remotely on June 30.8 with a 0.35-m f/3 Cassegrain reflector located at Siding Spring, NSW, Australia, show a small, condensed coma of size 3".5 (and mag 18.1-18.3) with a faint but distinct straight 6"-long tail in p.a. 230 degrees. T. Prystavski (Lviv, Ukraine) reports that CCD exposures taken remotely on July 7.4 with a 0.51-m f/6.8 "corrected Dall-Kirkham" telescope located at Rio Hurtado show clear cometary activity, with a very condensed coma of total mag 18.3 and a short tail about 0'.8 long in p.a. 222 degrees. The following orbital elements by S. Nakano (Central Bureau) are from 39 observations spanning 2024 Nov. 28-2025 July 9 (mean residual 0".6). The comet passed 2.07 AU from Jupiter on 2024 Sept. 9 UT. Epoch = 2025 May 5.0 TT T = 2025 May 20.91066 TT Peri. = 243.48615 e = 0.8788703 Node = 239.08907 2000.0 q = 2.0595944 AU Incl. = 109.21432 a = 17.0032228 AU n = 0.01405747 P = 70.11 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 13.0 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2025 06 14 04 06.21 -31 53.3 2.417 2.077 58.6 24.7 18.1 2025 06 24 04 25.46 -36 32.3 2.313 2.095 64.9 26.1 18.0 2025 07 04 04 47.94 -41 54.0 2.221 2.118 70.9 27.0 18.0 2025 07 14 05 15.02 -47 53.1 2.149 2.147 76.2 27.4 18.0 2025 07 24 05 48.95 -54 15.5 2.107 2.181 80.4 27.3 18.0 2025 08 03 06 33.28 -60 34.7 2.101 2.219 83.0 27.0 18.1 2025 08 13 07 33.06 -66 10.3 2.135 2.262 83.8 26.4 18.2 2025 08 23 08 52.44 -70 11.9 2.208 2.309 82.8 25.7 18.4 2025 09 02 10 25.94 -71 57.8 2.315 2.360 80.0 24.9 18.6 2025 09 12 11 55.00 -71 30.8 2.452 2.415 76.0 23.9 18.8 2025 09 22 13 05.88 -69 40.3 2.608 2.472 71.1 22.6 19.0 2025 10 02 13 58.70 -67 17.4 2.777 2.532 65.6 21.1 19.3 2025 10 12 14 38.59 -64 51.8 2.951 2.595 59.7 19.4 19.5 2025 10 22 15 10.00 -62 36.6 3.123 2.660 53.8 17.6 19.7 2025 11 01 15 35.80 -60 36.4 3.288 2.726 48.1 15.7 19.9 2025 11 11 15 57.69 -58 51.7 3.441 2.795 42.7 13.9 20.1 2025 11 21 16 16.76 -57 21.6 3.578 2.865 38.0 12.3 20.3 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 July 10 (CBET 5581) Daniel W. E. Green