Electronic Telegram No. 5494 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 A2 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala (discovery observations tabulated below). Four 45-s w-band survey images taken on Jan. 7 in 1".1-1".3 seeing show a very condensed head of size 1".4 (full-width-at- half-maximum) with a straight 5"-long tail in p.a. 310 degrees. 2025 UT R.A. (2000) Decl. Mag. Jan. 7.41644 8 33 10.87 - 7 16 11.5 21.0 7.42769 8 33 10.52 - 7 16 11.0 20.7 7.43897 8 33 10.18 - 7 16 10.4 20.8 7.45031 8 33 09.83 - 7 16 09.8 20.8 Weryk also identified, in the Minor Planet Center's "isolated tracklet file", images of the comet obtained with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala on 2024 Dec. 23.5 UT (at mag 20.9-21.0) and on 2024 Dec. 27.5 (at mag 20.8-21.0). After the comet was posted on the MPC's PCCP webpage, S. Deen (Simi Valley, CA, USA) found archival observations of this object in publicly available images obtained with the Cerro Tololo 4-m reflector (+ DECam) from 2024 Nov. 27.29 UT (magnitude V = 21.5), 28.29 (g = 22.0), and 30.29 (g = 21.8); the object did not appear obviously cometary in any of the images except for possibly on Nov. 28, when it may have had a 1".5-long tail towards p.a. 335 degrees and an essentially stellar nuclear condensation in 1".0 seeing. Deen also identified the comet in archival images obtained on 2024 Dec. 1.44-1.46 with the Mt. Lemmon 1.5-m reflector (no magnitude given), with no obvious cometary appearance; he adds that a single Mt. Lemmon image taken on 2024 Nov. 1 show nothing at the predicted position to limiting mag 22.0. The available astrometry appears on MPEC 2025-A162 and includes Mt. Lemmon observations from 2024 Dec. 27.4 UT that had been in the ITF. Note that an apparently asteroidal 20th-mag object with a nearly parabolic orbit that was discovered on Jan. 2 with the Mt. Lemmon survey (with pre-discovery observations identified back to 2024 Oct. 28) was given the designation A/2025 A1 (cf. MPEC 2025-A108), so this new comet receives the designation P/2025 A2. The following 2-body orbital elements by S. Nakano (Central Bureau) are from 30 observations spanning 2024 Nov. 27-2025 Jan. 9 (mean residual 0".2); they indicate that the comet passed 0.32 AU from Jupiter on 2022 Oct. 30 UT. T = 2024 Oct. 6.04820 TT Peri. = 278.11246 e = 0.3222238 Node = 189.31960 2000.0 q = 3.4465257 AU Incl. = 20.73326 a = 5.0850502 AU n = 0.08595303 P = 11.47 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 15.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 12 16 03 40.69 +41 41.0 2.347 3.237 150.0 8.7 20.9 2024 12 26 03 15.72 +41 27.1 2.526 3.321 137.9 11.4 21.2 2025 01 05 02 56.73 +40 55.9 2.737 3.406 125.7 13.6 21.4 2025 01 15 02 43.32 +40 21.7 2.972 3.490 114.1 14.9 21.7 2025 01 25 02 34.60 +39 53.0 3.221 3.575 103.1 15.6 22.0 2025 02 04 02 29.64 +39 33.9 3.477 3.660 92.8 15.6 22.2 2025 02 14 02 27.63 +39 26.0 3.732 3.745 83.1 15.2 22.4 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 January 11 (CBET 5494) Daniel W. E. Green