Electronic Telegram No. 5448 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/2024 R3 (PANSTARRS) Yudish Ramanjooloo, Institute for Astronomy, University of Hawaii, reports the discovery of another comet in images obtained on Sept. 8 UT with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala (discovery observations tabulated below). Four 45-s w-band survery images taken in 1".0 seeing show a condensed head of size 2".8 (full-width-at-half- maximum) with a straight 11" tail toward p.a. 247 degrees. 2024 UT R.A. (2000) Decl. Mag. Sept. 8.49160 2 33 38.60 + 9 50 06.6 21.1 8.50289 2 33 38.51 + 9 50 09.7 20.7 8.51422 2 33 38.43 + 9 50 12.2 20.7 8.52559 2 33 38.34 + 9 50 15.2 20.6 R. Weryk, Department of Physics and Astronomy, University of Western Ontario, writes that two 60-s w-band follow-up Pan-STARRS2 exposures taken on Sept. 9.5 UT in 1".2 seeing show a condensed head of size about 1".8 (FWHM) with an 18" tail toward p.a. 245 degrees. After the comet was posted to the Minor Planet Center's PCCP webpage, H. Sato (Bunkyo-ku, Tokyo, Japan) obtained sixteen stacked 60-s CCD exposures remotely on Sept. 9.39-9.40 UT using a 0.51-m f/6.8 astrograph located at the Utah Desert Remote Observatory (near Beryl Junction, UT, USA) show a poorly condensed coma of size 5" x 10", and elongated westwards; the magnitude was 19.6 as measured within a circular aperture of radius 4".9. Twenty stacked 60-s CCD exposures obtained by Sato remotely on Sept. 14.8 with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW, Australia, show a moderately condensed coma of size 4" x 10", elongated westwards, with a fan-like tail 10" long spanning p.a. 220-280 degrees; the magnitude was 20.1 as measured within a circular aperture of radius 5".4. The available astrometry appears on MPEC 2024-S11. The following two- body elliptical orbital elements by S. Nakano (Central Buerau) are from 45 observations spanning 2024 Sept. 8-14 (mean residual 0".6). There are no close approaches to major planets. T = 2024 May 6.77098 TT Peri. = 308.73840 e = 0.2728275 Node = 33.31163 2000.0 q = 2.3443028 AU Incl. = 14.73842 a = 3.2238608 AU n = 0.17027060 P = 5.79 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 14.5 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 09 07 02 33.74 +09 43.8 1.727 2.450 125.2 19.6 19.6 2024 09 17 02 31.83 +10 23.5 1.651 2.467 135.1 16.7 19.5 2024 09 27 02 27.03 +10 56.4 1.591 2.485 145.9 13.1 19.5 2024 10 07 02 19.63 +11 22.9 1.552 2.504 157.3 8.8 19.4 2024 10 17 02 10.39 +11 44.0 1.538 2.524 169.3 4.2 19.5 2024 10 27 02 00.36 +12 01.4 1.551 2.544 178.5 0.6 19.5 2024 11 06 01 50.73 +12 17.7 1.592 2.566 166.3 5.2 19.6 2024 11 16 01 42.64 +12 36.0 1.660 2.588 154.5 9.5 19.7 2024 11 26 01 36.84 +12 59.1 1.753 2.611 143.2 13.1 19.9 2024 12 06 01 33.72 +13 28.9 1.866 2.634 132.5 16.0 20.1 2024 12 16 01 33.37 +14 06.5 1.996 2.658 122.5 18.2 20.2 2024 12 26 01 35.61 +14 51.9 2.139 2.683 113.1 19.7 20.4 2025 01 05 01 40.19 +15 44.6 2.291 2.708 104.3 20.6 20.6 2025 01 15 01 46.82 +16 43.6 2.449 2.733 96.0 21.0 20.8 2025 01 25 01 55.20 +17 47.6 2.610 2.759 88.1 20.9 21.0 2025 02 04 02 05.08 +18 55.4 2.770 2.785 80.6 20.4 21.2 2025 02 14 02 16.24 +20 05.8 2.929 2.811 73.4 19.7 21.3 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 September 17 (CBET 5448) Daniel W. E. Green