Electronic Telegram No. 5518 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/2025 E1 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in images obtained on Mar. 2 with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala (discovery observations tabulated below); four 45-s w-band survey images taken in 1".2 seeing show a very condensed head of size 1".6 (full-width-at-half-maximum) with no tail. 2025 UT R.A. (2000) Decl. Mag. Mar. 2.42936 11 02 08.59 -19 53 55.0 20.6 2.44027 11 02 08.10 -19 53 56.2 20.8 2.45119 11 02 07.59 -19 53 57.5 20.6 2.54257 11 02 03.41 -19 54 07.1 20.5 2.54450 11 02 03.33 -19 54 07.2 20.3 Three 60-s gri-band follow-up images obtained by Weryk and R. Wainscoat on Mar. 3.49 UT with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea (queue observer A. Acohido; queue coordinator V. Khatu) in 0".8 seeing show a condensed head of size 1".2 (FWHM) with a broad tail about 0".5 long spanning p.a. 80-130 degrees. Weryk identified pre-discovery images taken with the Pan-STARRS1 telescope on Jan. 3.6 (mag 21.7-22.3), as well as images taken with with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala on Jan. 4.6 (mag 21.4-22.0) and on Jan. 25.53-25.56 (mag 20.5-21.3). The available astrometry appears on MPEC 2025-E58. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 21 observations Jan. 3-Mar. 3 (mean residual 0".2); there are no close approaches to major planets. T = 2026 Sept.23.19165 TT Peri. = 274.46472 Node = 344.60820 2000.0 q = 3.9929371 AU Incl. = 69.09118 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 10.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2025 02 14 11 13.77 -19 11.5 5.446 6.251 141.6 5.6 20.0 2025 02 24 11 06.88 -19 40.4 5.321 6.192 149.3 4.7 20.0 2025 03 06 10 59.44 -19 59.7 5.226 6.134 154.2 4.0 19.9 2025 03 16 10 51.79 -20 09.8 5.162 6.076 154.7 4.0 19.8 2025 03 26 10 44.30 -20 11.6 5.130 6.019 150.6 4.7 19.8 2025 04 05 10 37.32 -20 06.7 5.127 5.961 143.6 5.7 19.8 2025 04 15 10 31.17 -19 57.3 5.150 5.904 135.2 6.9 19.7 2025 04 25 10 26.06 -19 45.8 5.197 5.847 126.2 8.0 19.7 2025 05 05 10 22.17 -19 34.6 5.262 5.791 117.1 8.9 19.7 2025 05 15 10 19.54 -19 26.1 5.340 5.735 108.1 9.6 19.7 2025 05 25 10 18.18 -19 21.9 5.426 5.679 99.3 10.1 19.7 2025 06 04 10 18.04 -19 23.5 5.517 5.623 90.8 10.4 19.7 2025 06 14 10 19.04 -19 32.1 5.606 5.568 82.7 10.4 19.7 2025 06 24 10 21.07 -19 48.3 5.692 5.514 74.8 10.2 19.7 2025 07 04 10 24.04 -20 12.7 5.770 5.460 67.3 9.9 19.7 2025 07 14 10 27.83 -20 45.5 5.838 5.406 60.2 9.4 19.7 2025 07 24 10 32.33 -21 26.9 5.893 5.353 53.6 8.8 19.7 2025 08 03 10 37.45 -22 17.1 5.933 5.300 47.5 8.1 19.7 2025 08 13 10 43.08 -23 15.9 5.957 5.248 42.0 7.4 19.6 2025 11 01 11 36.04 -36 19.4 5.525 4.853 43.5 8.1 19.2 2025 11 11 11 42.21 -38 36.1 5.403 4.807 48.7 8.9 19.1 2025 11 21 11 47.84 -41 01.2 5.271 4.761 54.2 9.7 19.0 2025 12 01 11 52.74 -43 34.2 5.131 4.717 60.1 10.4 18.9 2025 12 11 11 56.66 -46 14.4 4.987 4.674 66.0 11.1 18.8 2025 12 21 11 59.29 -49 01.0 4.840 4.631 72.0 11.7 18.7 2025 12 31 12 00.22 -51 52.2 4.695 4.590 77.8 12.1 18.7 2026 01 10 11 58.97 -54 45.7 4.554 4.549 83.5 12.4 18.6 2026 01 20 11 54.90 -57 38.3 4.420 4.510 88.9 12.6 18.5 2026 01 30 11 47.28 -60 25.3 4.295 4.472 93.9 12.7 18.4 2026 02 09 11 35.37 -63 00.6 4.182 4.435 98.4 12.7 18.3 2026 02 19 11 18.52 -65 17.0 4.084 4.399 102.1 12.7 18.2 2026 03 01 10 56.67 -67 06.0 4.000 4.364 105.1 12.7 18.1 2026 03 11 10 30.74 -68 20.5 3.933 4.331 107.1 12.7 18.1 2026 03 21 10 02.88 -68 56.3 3.881 4.299 108.3 12.7 18.0 2026 03 31 09 36.05 -68 54.7 3.845 4.268 108.5 12.8 18.0 2026 04 10 09 12.87 -68 22.4 3.823 4.239 107.9 13.0 17.9 2026 04 20 08 54.82 -67 29.4 3.813 4.211 106.6 13.2 17.9 2026 04 30 08 42.25 -66 26.0 3.813 4.185 104.8 13.5 17.9 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 March 3 (CBET 5518) Daniel W. E. Green