Electronic Telegram No. 5440 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 Q3 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in images obtained with the Pan-STARRS2 (Aug. 27.4 UT) and Pan-STARRS1 (Aug. 27.5) 1.8-m Ritchey-Chretien reflectors at Haleakala (discovery observations tabulated below). The Aug. 27 Pan-STARRS2 images show a soft appearance but no definite coma or tail. 2024 UT R.A. (2000) Decl. Mag. Aug. 27.41176 22 27 47.01 - 5 41 56.8 21.0 27.42368 22 27 44.92 - 5 41 55.5 21.2 27.43562 22 27 42.85 - 5 41 54.4 21.0 27.44752 22 27 40.76 - 5 41 53.0 21.4 27.51686 22 27 28.69 - 5 41 45.8 21.1 27.51751 22 27 28.57 - 5 41 46.0 20.6 27.52154 22 27 27.87 - 5 41 45.3 21.2 27.52219 22 27 27.75 - 5 41 45.4 20.7 Three 60-s gri-band follow-up images obtained by Weryk and R. Wainscoat with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea on Aug. 31.4 UT in 1".0 seeing (queue observer J. Silva; queue coordinator V. Khatu) show a very condensed head of size 1".2 (full-width-at-half-maximum) with a straight, 3" tail toward p.a. 130 degrees. Weryk adds that four 45-s Pan-STARRS1 w-band survey images taken on Sept. 5.4 in 1".4 seeing show a condensed head of size 1".9 (FWHM) and a 4" tail in p.a. 125 degrees. After the comet was posted on the Minor Planet Center's PCCP webpage, H. Sato (Bunkyo-ku, Tokyo, Japan) reported that thirty-two stacked 30-s CCD exposures taken remotely with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW, Australia, on Aug. 31.47 UT show only a stellar appearance; the magnitude was 20.8 as measured within a circular aperture of radius 3".2. The available astrometry appears on MPEC 2024-R181. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 53 observations spanning 2024 July 29-Sept. 5 (mean residual 0".3). There are no close approaches to major planets. T = 2025 Mar. 5.36647 TT Peri. = 70.18526 Node = 337.28242 2000.0 q = 2.0904620 AU Incl. = 121.35720 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 14.5 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 08 18 22 53.55 -05 57.2 2.110 3.091 162.8 5.6 20.0 2024 08 28 22 26.09 -05 40.9 2.005 3.013 175.9 1.4 19.8 2024 09 07 21 56.49 -05 21.4 1.956 2.936 163.4 5.6 19.7 2024 09 17 21 27.27 -04 56.9 1.965 2.861 147.0 11.0 19.6 2024 09 27 21 00.80 -04 27.5 2.023 2.787 131.2 15.7 19.6 2024 10 07 20 38.60 -03 53.7 2.121 2.715 116.3 19.3 19.6 2024 10 17 20 21.18 -03 16.1 2.244 2.646 102.6 21.6 19.6 2024 10 27 20 08.27 -02 34.8 2.379 2.578 90.0 22.7 19.7 2024 11 06 19 59.29 -01 49.2 2.516 2.514 78.5 22.7 19.7 2024 11 16 19 53.53 -00 58.1 2.646 2.453 67.9 21.9 19.7 2024 11 26 19 50.32 -00 00.6 2.762 2.395 58.2 20.5 19.7 2024 12 06 19 49.09 +01 04.7 2.859 2.341 49.4 18.6 19.7 2024 12 16 19 49.36 +02 19.4 2.931 2.291 41.6 16.6 19.7 2025 03 06 20 03.79 +22 13.4 2.538 2.090 52.6 22.2 19.1 2025 03 16 20 01.60 +26 52.6 2.397 2.094 60.5 24.4 19.0 2025 03 26 19 56.28 +32 18.2 2.255 2.105 68.5 26.2 18.9 2025 04 05 19 46.08 +38 32.9 2.120 2.122 76.4 27.3 18.7 2025 04 15 19 28.07 +45 29.9 2.006 2.145 83.9 27.7 18.7 2025 04 25 18 57.29 +52 43.2 1.925 2.175 90.2 27.5 18.6 2025 05 05 18 06.46 +59 12.4 1.889 2.210 94.5 27.1 18.6 2025 05 15 16 51.26 +63 18.0 1.904 2.251 96.3 26.5 18.7 2025 05 25 15 25.54 +63 35.7 1.973 2.297 95.1 26.1 18.9 2025 06 04 14 15.73 +60 32.1 2.089 2.347 91.5 25.6 19.1 2025 06 14 13 30.32 +55 50.7 2.244 2.402 86.2 25.0 19.3 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 September 8 (CBET 5440) Daniel W. E. Green