Electronic Telegram No. 5478 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 W1 (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). 2024 UT R.A. (2000) Decl. Mag. Nov. 22.60604 9 50 31.05 -30 03 59.4 20.7 22.61710 9 50 31.01 -30 04 20.0 20.8 22.63923 9 50 30.92 -30 05 01.2 20.6 Three 60-s gri-band follow-up images were obtained on Nov. 27.6 UT with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea by Weryk and R. Wainscoat (queue observer J. Silva; queue coordinator H. Flewelling) in 1".3 seeing that show a very condensed head of size 1".6 (full-width-at-half-maximum) with a 10" tail toward p.a. 325 degrees. After the comet was posted to the Minor Planet Center's PCCP webpage, H. Sato (Bunkyo-ku, Tokyo, Japan) found only a stellar appearance on twelve stacked 60-s CCD exposures taken remotely on Nov. 23.7 with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW; the magnitude was 20.5 as measured within a circular aperture of radius 3".2. Additional observations are givevn on MPEC 2024-X279. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 20 observations spanning 2024 Nov. 22-Dec. 6 (mean residual 0".7). There are no close approaches to minor planets. T = 2025 Mar. 16.11226 TT Peri. = 255.95781 Node = 310.93155 2000.0 q = 2.5804588 AU Incl. = 83.24247 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 14.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 11 26 09 50.21 -31 50.3 2.786 2.833 82.6 20.2 19.8 2024 12 06 09 47.17 -37 17.7 2.642 2.792 88.2 20.7 19.7 2024 12 16 09 40.05 -43 00.5 2.521 2.753 93.0 20.9 19.5 2024 12 26 09 27.34 -48 46.4 2.425 2.718 96.5 21.1 19.4 2025 01 05 09 07.03 -54 16.1 2.358 2.687 98.6 21.2 19.3 2025 01 15 08 37.14 -59 03.4 2.320 2.659 99.1 21.4 19.2 2025 01 25 07 57.00 -62 39.2 2.310 2.636 98.1 21.7 19.2 2025 02 04 07 09.63 -64 40.6 2.325 2.616 95.8 22.0 19.2 2025 02 14 06 22.28 -65 05.5 2.360 2.601 92.7 22.3 19.2 2025 02 24 05 42.13 -64 15.3 2.407 2.589 89.2 22.5 19.2 2025 03 06 05 12.31 -62 41.8 2.462 2.583 85.6 22.5 19.3 2025 03 16 04 52.17 -60 53.5 2.519 2.580 82.2 22.5 19.3 2025 03 26 04 39.71 -59 08.9 2.573 2.583 79.4 22.3 19.3 2025 04 05 04 32.98 -57 39.6 2.621 2.589 77.1 22.1 19.4 2025 04 15 04 30.42 -56 32.2 2.660 2.600 75.7 21.9 19.4 2025 04 25 04 30.95 -55 50.3 2.689 2.615 75.0 21.8 19.5 2025 05 05 04 33.79 -55 36.4 2.706 2.635 75.2 21.7 19.5 2025 05 15 04 38.36 -55 52.4 2.712 2.659 76.2 21.7 19.6 2025 05 25 04 44.29 -56 39.5 2.708 2.686 77.9 21.6 19.6 2025 06 04 04 51.27 -57 59.2 2.696 2.717 80.4 21.6 19.6 2025 06 14 04 59.06 -59 52.7 2.678 2.752 83.3 21.5 19.7 2025 06 24 05 07.49 -62 20.6 2.658 2.791 86.7 21.3 19.7 2025 07 04 05 16.38 -65 22.9 2.640 2.832 90.2 21.0 19.7 2025 07 14 05 25.52 -68 58.4 2.629 2.877 93.6 20.6 19.8 2025 07 24 05 34.69 -73 04.2 2.628 2.924 96.6 20.2 19.8 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 December 11 (CBET 5478) Daniel W. E. Green