Electronic Telegram No. 5313 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/2023 V3 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in images obtained on Nov. 3 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".3 seeing show a diffuse coma of size around 1".8 (full-width-at-half-maximum) with a possible straight 4" tail in p.a. 280 degrees. 2023 UT R.A. (2000) Decl. Mag. Nov. 3.45563 3 32 09.03 -23 17 52.6 20.5 3.46816 3 32 08.56 -23 17 51.9 21.3 3.48070 3 32 08.12 -23 17 50.9 20.7 3.49323 3 32 07.65 -23 17 49.4 21.0 3.55205 3 32 05.53 -23 17 44.9 21.9 3.55287 3 32 05.46 -23 17 44.9 21.2 Pre-discovery Pan-STARRS1 observations were identified in the Minor Planet Center's "isolated tracklet file" from Oct. 11.5 UT (mag 21.3-21.8). Also, additional Pan-STARRS1 observations were subsequently reported from Sept. 25.5 (mag 20.5-21.7), Oct. 7.54-7.57 (mag 20.7-21.5), and Oct. 30.5 (mag 21.0-21.9) -- as were observations made with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala on Oct. 15.5 (mag 20.9-21.1). After the comet was posted on the MPC's PCCP webpage, other CCD astrometrists have commented on the comet's appearance. Exposures obtained by M. T. Read with the Spacewatch 1.8-m f/2.7 reflector at Kitt Peak on Nov. 5.34-5.35 UT show a "slight" coma and a tail about 10" long toward p.a. 270 degrees. Ten stacked 120-s exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) with a "Deep Sky Chile" 0.51-m f/6.8 astrograph at Rio Hurtado, Chile, on Nov. 6.2 show a strongly condensed coma 4" in diameter with a fan-like tail 10" long spanning p.a. 265-315 degrees; the magnitude was 20.9 as measured within a circular aperture of radius 2".2. The available astrometry appears on MPEC 2023-V109. The following elliptical orbital elements by S. Nakano (Central Bureau) are from 34 observations spanning 2023 Sept. 25-Nov. 6 (mean residual 0".3). These indicate that the comet will pass 0.84 AU from Jupiter on 2025 Feb. 23 UT. T = 2023 Aug. 6.21148 TT Peri. = 291.51351 e = 0.6624167 Node = 91.50178 2000.0 q = 4.4705627 AU Incl. = 40.25114 a = 13.2428450 AU n = 0.02045183 P = 48.19 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 12.5 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2023 10 23 03 38.54 -23 22.5 3.729 4.500 136.1 8.8 20.6 2023 11 02 03 33.01 -23 19.6 3.714 4.508 138.8 8.3 20.6 2023 11 12 03 26.93 -22 59.7 3.721 4.517 139.2 8.2 20.6 2023 11 22 03 20.79 -22 21.4 3.752 4.527 137.2 8.5 20.6 2023 12 02 03 15.07 -21 25.1 3.807 4.538 133.0 9.1 20.7 2023 12 12 03 10.18 -20 12.3 3.885 4.550 127.3 9.9 20.7 2023 12 22 03 06.46 -18 45.7 3.982 4.562 120.6 10.7 20.8 2024 01 01 03 04.10 -17 08.4 4.098 4.576 113.2 11.4 20.8 2024 01 11 03 03.18 -15 23.6 4.228 4.590 105.6 11.9 20.9 2024 01 21 03 03.71 -13 34.3 4.369 4.605 97.7 12.2 21.0 2024 01 31 03 05.63 -11 43.1 4.517 4.622 89.9 12.3 21.1 2024 02 10 03 08.83 -09 52.1 4.669 4.639 82.2 12.2 21.2 2024 02 20 03 13.18 -08 02.9 4.822 4.656 74.5 11.8 21.3 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2023 CBAT 2023 November 8 (CBET 5313) Daniel W. E. Green