Electronic Telegram No. 5379 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 F1 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in four 45-s w-band survey images obtained in 1".2-1".4 seeing with the Pan-STARRS1 1.8-m reflector at Haleakala on Mar. 18 (discovery observations tabulated below). The very condensed coma showed a size of 1".8 (full-width-at-half-maximum) in stacked images, and there was a clear 8" tail in p.a. 305 degrees. 2024 UT R.A. (2000) Decl. Mag. Mar. 18.41096 11 56 42.07 -12 37 58.8 20.7 18.42262 11 56 41.51 -12 37 54.3 20.9 18.43427 11 56 40.95 -12 37 49.7 20.6 18.44593 11 56 40.41 -12 37 45.2 21.3 18.52141 11 56 36.81 -12 37 14.5 21.0 18.52222 11 56 36.78 -12 37 14.2 21.1 Weryk adds that four additional stacked 45-s Pan-STARRS1 w-band survey images taken in 1".3-1".4 seeing on Mar. 30.33-30.37 UT show a condensed coma of size 1".8 (FWHM) and a straight 6" tail in p.a. 305 degrees. He further notes that images from Feb. 15 show the comet with a clear 8" tail in p.a. 300 degrees, but he was unable to measure astrometry because the comet's head was lost in a "cell gap" on the camera chip. Weryk further adds that three 60-s gri-band follow-up images were obtained via R. Wainscoat with the 3.6-m Canada-France- Hawaii Telescope at Mauna Kea in 1".0 seeing on Apr. 5.47 (queue oberver L. Wells; queue coordinator T. Burdullis, which show this clearly to be a comet in the best image, with a very condensed coma of size 1".4 (FWHM) and a 9" tail in p.a. 305 degrees. After the comet was posted on the Minor Planet Center's PCCP webpage, H. Sato (Bunkyo-ku, Tokyo, Japan) obtained ten stacked 120-s CCD exposures remotely on Mar. 18.56-18.57 UT with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW, Australia, showing a strongly condensed coma 6" in diameter with no tail; the magnitude was 20.6 as measured within a circular aperture of radius 3".2. The available astrometry appears on MPEC 2024-G102. The following elliptical orbital elements by S. Nakano (Central Bureau) are from 40 observations spanning 2024 Mar. 18-Apr. 6. The comet passed 0.62 AU from Jupiter on 2021 Feb. 17 UT. T = 2023 Oct. 25.67633 TT Peri. = 229.53400 e = 0.4597310 Node = 251.55325 2000.0 q = 1.8594016 AU Incl. = 7.00390 a = 3.4416217 AU n = 0.15436875 P = 6.38 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 15.5 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 03 31 11 47.91 -11 04.9 1.282 2.263 165.7 6.3 19.6 2024 04 10 11 42.67 -09 47.5 1.351 2.307 157.1 9.7 19.8 2024 04 20 11 39.75 -08 37.3 1.443 2.352 147.4 13.3 20.0 2024 04 30 11 39.36 -07 40.8 1.554 2.397 137.7 16.4 20.3 2024 05 10 11 41.44 -07 00.8 1.683 2.444 128.6 18.8 20.5 2024 05 20 11 45.76 -06 38.4 1.826 2.491 120.0 20.6 20.8 2024 05 30 11 51.99 -06 32.4 1.980 2.538 111.9 21.8 21.0 2024 06 09 11 59.81 -06 41.1 2.142 2.585 104.2 22.4 21.3 2024 06 19 12 08.95 -07 02.8 2.310 2.633 96.9 22.5 21.5 2024 06 29 12 19.15 -07 35.1 2.481 2.681 90.0 22.3 21.8 2024 07 09 12 30.21 -08 16.2 2.655 2.729 83.3 21.7 22.0 2024 07 19 12 41.97 -09 04.4 2.828 2.777 76.7 20.9 22.2 2024 07 29 12 54.30 -09 58.0 3.000 2.825 70.4 19.8 22.4 2024 08 08 13 07.11 -10 55.6 3.168 2.873 64.1 18.5 22.6 2024 08 18 13 20.31 -11 55.9 3.330 2.920 57.9 17.1 22.8 2024 08 28 13 33.83 -12 57.9 3.486 2.968 51.7 15.5 22.9 2024 09 07 13 47.63 -14 00.4 3.634 3.015 45.5 13.8 23.1 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 April 9 (CBET 5379) Daniel W. E. Green