Electronic Telegram No. 5513 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 D3 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in images obtained with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala (discovery observations tabulated below). Four 45-s w-band survey images taken in variable seeing show a condensed object with a soft appearance but no tail. 2025 UT R.A. (2000) Decl. Obs. Feb. 22.43215 11 17 24.29 - 0 56 41.0 21.6 22.44303 11 17 23.90 - 0 56 37.4 21.5 22.45393 11 17 23.52 - 0 56 33.7 21.6 22.46486 11 17 23.14 - 0 56 29.6 21.8 Weryk and R. Wainscoat obtained three 60-s gri-band follow-up images with the 3.6-m Canada-France-Hawaii telescope at Mauna Kea on Feb. 23.5 UT (queue observer L. Wells; queue coordinator V. Khatu) in 1".1 seeing that show a condensed head of size 1".4 (full-width-at-half-maximum) with a broad tail about 8" long spanning p.a. 290-305 degrees. Weryk also identified pre- discovery observations of this comet obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on 2024 Dec. 30.65 UT (at mag 21.7), 2025 Jan. 6.6 (at mag 21.9-22.4), Feb. 6.5 (at mag 20.3-20.4), and Feb. 7.56 (at mag 21.3). The available astrometry appears on MPEC 2025-D211. The following two-body elliptical orbital elements by S. Nakano (Central Bureau) are from 32 observations spanning 2024 Dec. 30-2025 Feb. 26 (mean residual 0".2). The comet passed 0.64 AU from Jupiter on 2021 Dec. 22 UT. T = 2024 July 26.11503 TT Peri. = 294.59501 e = 0.2514919 Node = 186.62684 2000.0 q = 2.9670984 AU Incl. = 9.64830 a = 3.9640163 AU n = 0.12488231 P = 7.89 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 13.5 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2025 02 14 11 21.74 -01 41.5 2.219 3.130 152.8 8.3 20.2 2025 02 24 11 16.52 -00 47.4 2.182 3.145 164.2 4.9 20.2 2025 03 06 11 10.54 +00 16.2 2.173 3.161 174.4 1.8 20.2 2025 03 16 11 04.54 +01 23.8 2.193 3.178 170.4 3.0 20.2 2025 03 26 10 59.20 +02 29.6 2.241 3.195 159.5 6.3 20.3 2025 04 05 10 55.11 +03 28.7 2.317 3.212 148.5 9.4 20.4 2025 04 15 10 52.68 +04 17.0 2.415 3.230 137.8 12.0 20.5 2025 04 25 10 52.07 +04 52.6 2.533 3.248 127.8 14.2 20.6 2025 05 05 10 53.33 +05 14.7 2.667 3.267 118.2 15.8 20.8 2025 05 15 10 56.37 +05 23.4 2.812 3.286 109.2 16.9 20.9 2025 05 25 11 00.99 +05 19.6 2.964 3.305 100.7 17.5 21.1 2025 06 04 11 07.04 +05 04.5 3.122 3.325 92.6 17.7 21.2 2025 06 14 11 14.29 +04 39.2 3.280 3.345 84.8 17.6 21.3 2025 06 24 11 22.58 +04 05.2 3.438 3.365 77.4 17.1 21.5 2025 07 04 11 31.73 +03 23.6 3.592 3.386 70.2 16.4 21.6 2025 07 14 11 41.60 +02 35.6 3.741 3.407 63.3 15.5 21.7 2025 07 24 11 52.07 +01 42.3 3.882 3.428 56.5 14.3 21.8 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 February 26 (CBET 5513) Daniel W. E. Green