Electronic Telegram No. 5514 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 P/2025 D4 (ATLAS) An apparently asteroidal object discovered on CCD images taken on Feb. 24.3 UT with a 0.5-m f/2 Schmidt reflector at Rio Hurtado, Chile, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program has been found to show cometary appearance by CCD astrometrists elsewhere. The discovery observations are tabulated below, together with pre-discovery ATLAS observations subsequently identified from the previous night. 2025 UT R.A. (2000) Decl. Mag. Feb. 23.32394 14 42 43.89 -23 58 26.5 19.2 23.33550 14 42 44.24 -23 58 27.7 18.9 24.30865 14 43 14.24 -23 59 03.0 18.9 24.31141 14 43 14.34 -23 59 01.7 18.9 24.31429 14 43 14.42 -23 59 02.5 19.1 24.31942 14 43 14.59 -23 59 03.3 19.2 After the comet was posted on the Minor Planet Center's NEOCP webpage, R. Weryk (Department of Physics and Astronomy, University of Western Ontario) identified pre-discovery images obtained with the Pan-STARRS2 1.8-m Ritchey- Chretien reflector at Haleakala on 2023 Dec. 10.6 UT (at mag 23.3), 2023 Dec. 14.6 (mag 13.2), and 2024 Jan. 5.5 (mag 22.4), as well as pre-discovery images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on 2023 Dec. 18.6 (mag 22.5), 2023 Dec. 23.6 (mag 22.9), 2024 Mar. 29.3 (mag 20.8-21.4), 2024 Apr. 27.24 (mag 21.5), 2024 May 8.26 (mag 21.3), 2024 May 22.26 (mag 20.8), 2024 May 26.26 (mag 20.8), and 2025 May 6.6 (mag 20.4). Pan-STARRS2 observations from 2024 Feb. 6.4 (at mag 21.6-21.9) were also in the MPC's "isolated tracklet file". Four 45-s w-band Pan-STARRS1 survey pre-discovery images from 2025 Jan. 6.6, obtained in 1".1 seeing, show a very condensed head of size 1".7 (full-width-at-half-maximum) with a tail > 10" long in p.a. 280 degrees. Four 45-s w-band Pan-STARRS1 survey images taken on 2025 Feb. 27.6 in 1".4-1".5 seeing show a very condensed head of size 2".0 (FWHM) with a 10" tail in p.a. 280 degrees. The available astrometry appears on MPEC 2025-D235. The following elliptical orbital elements by S. Nakano (Central Bureau) are from 42 observations spanning 2023 Dec. 10-2025 Feb. 27 (mean residual 0".3). There are no close approaches to any major planets. Epoch = 1998 Sept.24.0 TT T = 1998 Sept.24.96731 TT Peri. = 332.99451 e = 0.6336796 Node = 233.32267 2000.0 q = 3.2543514 AU Incl. = 15.93084 a = 8.8838936 AU n = 0.03722194 P = 26.48 years Epoch = 2025 Feb. 14.0 TT T = 2025 Feb. 14.28207 TT Peri. = 332.88954 e = 0.6342037 Node = 233.11948 2000.0 q = 3.2549282 AU Incl. = 15.94112 a = 8.8982001 AU n = 0.03713221 P = 26.54 years Epoch = 2051 Nov. 5.0 TT T = 2051 Oct. 22.44991 TT Peri. = 334.08130 e = 0.6385958 Node = 231.45836 2000.0 q = 3.2660925 AU Incl. = 15.73442 a = 9.0372289 AU n = 0.03627865 P = 27.17 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 11.5 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2025 02 14 14 37.08 -23 47.3 2.923 3.255 100.8 17.3 19.0 2025 02 24 14 43.08 -23 58.9 2.791 3.256 109.4 16.7 18.9 2025 03 06 14 47.22 -23 58.4 2.667 3.258 118.4 15.5 18.8 2025 03 16 14 49.39 -23 44.9 2.556 3.263 127.9 13.9 18.7 2025 03 26 14 49.61 -23 17.9 2.460 3.269 137.9 11.8 18.6 2025 04 05 14 47.99 -22 37.2 2.384 3.277 148.2 9.3 18.5 2025 04 15 14 44.89 -21 43.9 2.331 3.286 158.8 6.3 18.5 2025 04 25 14 40.80 -20 40.3 2.304 3.298 169.4 3.2 18.5 2025 05 05 14 36.32 -19 30.1 2.304 3.310 175.7 1.3 18.5 2025 05 15 14 32.10 -18 18.0 2.332 3.325 167.0 3.9 18.6 2025 05 25 14 28.72 -17 08.8 2.388 3.341 156.6 6.9 18.6 2025 06 04 14 26.60 -16 06.8 2.468 3.359 146.2 9.7 18.7 2025 06 14 14 26.04 -15 15.0 2.571 3.378 136.3 12.0 18.8 2025 06 24 14 27.13 -14 35.0 2.692 3.399 126.8 13.9 19.0 2025 07 04 14 29.88 -14 07.3 2.828 3.421 117.7 15.3 19.1 2025 07 14 14 34.22 -13 51.1 2.976 3.445 109.1 16.2 19.2 2025 07 24 14 40.00 -13 45.2 3.132 3.470 100.9 16.7 19.4 2025 08 03 14 47.09 -13 48.2 3.294 3.496 93.0 16.8 19.5 2025 08 13 14 55.35 -13 58.4 3.458 3.524 85.4 16.7 19.7 2025 08 23 15 04.61 -14 14.0 3.623 3.552 78.0 16.2 19.8 2025 09 02 15 14.77 -14 33.5 3.785 3.582 70.8 15.4 19.9 2025 09 12 15 25.69 -14 55.4 3.944 3.613 63.8 14.5 20.1 2025 09 22 15 37.26 -15 18.3 4.096 3.646 56.9 13.3 20.2 2025 10 02 15 49.39 -15 41.0 4.241 3.679 50.0 12.0 20.3 2025 10 12 16 01.97 -16 02.4 4.376 3.713 43.3 10.6 20.4 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 February 28 (CBET 5514) Daniel W. E. Green