Electronic Telegram No. 5443 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 R2 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in images obtained on Sept. 3 with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala (discovery observations tabulated below). The four 45-s w-band discovery survey images, taken in variable seeing (1".3-1".8) show a very diffuse coma of size about 2".4 in an image stack, with a straight 6" tail in p.a. 260 degrees. 2024 UT R.A. (2000) Decl. Mag. Sept. 3.53032 3 23 25.24 +13 23 02.6 20.7 3.54150 3 23 25.79 +13 22 59.5 20.9 3.55268 3 23 26.35 +13 22 55.6 20.9 3.56385 3 23 26.90 +13 22 52.3 20.7 3.62859 3 23 30.15 +13 22 32.9 21.4 3.62925 3 23 30.19 +13 22 32.6 21.4 Weryk adds that an earlier Pan-STARRS2 detection that had been made on Aug. 9.6 UT (and was in the Minor Planet Center's "isolated tracklet file") did not show obvious activity (the magnitude was given as 20.5-20.6). After the comet was posted on the MPC's PCCP webpage by Weryk, H. Sato (Bunkyo-ku, Tokyo, Japan) reported that twenty stacked 60-s CCD exposures taken remotely on Sept. 4.4 with a 0.43-m f/6.8 astrograph located at the Utah Desert Remote Observatory (near Beryl Junction, UT, USA) show a strongly condensed coma 8" in diameter with a hint of a tail 10" long toward p.a. 280 deg; the magnitude was 19.8 as measured within a circular aperture of radius 5".7. The available astrometry appears on MPEC 2024-R202. The following orbital elements by S. Nakano (Central Bureau) are from 35 observations spanning 2024 Aug. 9-Sept. 7 (mean residual 0".5). There are no close approaches to major planets. T = 2024 Oct. 1.90207 TT Peri. = 203.96586 e = 0.2653145 Node = 193.02762 2000.0 q = 2.3015973 AU Incl. = 15.10624 a = 3.1327653 AU n = 0.17775109 P = 5.545 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 15.0 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 08 18 03 06.35 +14 22.4 1.964 2.316 97.0 25.7 20.1 2024 08 28 03 17.31 +13 52.4 1.845 2.311 104.2 25.1 20.0 2024 09 07 03 26.28 +13 04.3 1.732 2.306 111.9 23.9 19.8 2024 09 17 03 32.87 +11 57.9 1.628 2.303 120.2 22.2 19.7 2024 09 27 03 36.80 +10 33.6 1.534 2.302 129.1 19.8 19.6 2024 10 07 03 37.82 +08 53.6 1.456 2.302 138.5 16.7 19.4 2024 10 17 03 35.96 +07 02.2 1.395 2.303 148.3 13.2 19.3 2024 10 27 03 31.57 +05 06.5 1.356 2.306 157.5 9.5 19.3 2024 11 06 03 25.35 +03 15.8 1.342 2.311 163.9 6.8 19.3 2024 11 16 03 18.36 +01 40.2 1.353 2.317 162.9 7.2 19.3 2024 11 26 03 11.75 +00 28.0 1.390 2.324 155.4 10.2 19.4 2024 12 06 03 06.58 -00 16.2 1.450 2.333 146.0 13.7 19.5 2024 12 16 03 03.60 -00 31.9 1.531 2.343 136.3 16.9 19.6 2024 12 26 03 03.17 -00 22.1 1.628 2.354 126.9 19.5 19.8 2025 01 05 03 05.37 +00 09.1 1.739 2.366 118.0 21.5 19.9 2025 01 15 03 10.08 +00 56.4 1.861 2.380 109.7 22.9 20.1 2025 01 25 03 17.03 +01 55.1 1.989 2.395 102.0 23.7 20.3 2025 02 04 03 25.98 +03 01.2 2.122 2.411 94.6 24.0 20.5 2025 02 14 03 36.64 +04 11.0 2.258 2.429 87.7 24.0 20.6 2025 02 24 03 48.75 +05 21.6 2.395 2.447 81.2 23.6 20.8 2025 03 06 04 02.09 +06 30.6 2.530 2.466 74.9 22.9 20.9 2025 03 16 04 16.47 +07 36.1 2.664 2.486 68.9 21.9 21.1 2025 03 26 04 31.70 +08 36.3 2.794 2.507 63.1 20.8 21.2 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 September 8 (CBET 5443) Daniel W. E. Green