Electronic Telegram No. 5460 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 T2 (RANKIN) David Rankin, Lunar and Planetary Laboratory, University of Arizona, reports his discovery of another comet on CCD images obtained on Oct. 4 with the Mt. Lemmon Survey 1.5-m reflector in Arizona (discovery observations tabulated below). The discovery images show a condensed 5" coma with a 7" tail in p.a. 270 degrees. 2024 UT R.A. (2000) Decl. Mag. Observer Oct. 4.43483 6 31 32.46 +12 27 20.5 21.1 Rankin 4.44028 6 31 32.99 +12 27 20.8 20.5 " 4.44573 6 31 33.56 +12 27 20.6 20.4 " 4.45119 6 31 34.14 +12 27 20.3 20.8 " 4.45982 6 31 34.95 +12 27 20.4 20.1 " 4.46312 6 31 35.33 +12 27 20.2 20.3 " 4.46653 6 31 35.64 +12 27 20.3 20.6 " After the comet was posted to the Minor Planet Center's PCCP webpage, R. Weryk (Department of Physics and Astronomy, University of Western Ontario) reported that J. Fairlamb obtained three 45-s exposures follow-up images of this object with the University of Hawaii 2.2-m telescope at Mauna Kea on Oct. 13.6 UT; Weryk's measurements of the image made in the best seeing (1".6) show a very condensed head of size 1".9 (full-width-at-half-maximum) with an obvious 12" straight tail in p.a. 280 degrees. Twenty-four stacked 60-s CCD exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) with a 0.43-m f/6.8 astrograph located at the Utah Desert Remote Observatory (near Beryl Junction, UT, USA) on Oc.t 14.5 show only a stellar appearance; the magnitude was 20.1 as measured within a circular aperture of radius 3".8. Fifteen 60-s exposures taken remotely by T. Prystavski (Lviv, Ukraine) with a 0.51-m f/4.5 Corrected Dall-Kirkham telescope at the Utah Desert Remote Observatory on Oct. 15.5 in local twilight show a slightly elongated object without an obvious coma (possibly a very short tail 0'.1 long in p.a. 283 degrees); the total mag was measured to be 20.1. The available astrometry appears on MPEC 2024-U16. The following elliptical two-body orbital elements by S. Nakano (Central Bureau) are from 49 observations spanning 2024 Oct. 4-17 (mean residual 0".52), with an orbital period uncertainty of +/- 1.6 years (mean error). However, Nakano notes that the comet appears to have passed 0.74 AU from Saturn on 2020 Jan. 2 UT and 1.56 AU from Jupiter in August 1994. T = 2024 Dec. 7.93352 TT Peri. = 343.58859 e = 0.6876969 Node = 113.15347 2000.0 q = 1.9759254 AU Incl. = 12.92356 a = 6.3269474 AU n = 0.06193166 P = 15.9 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 16.0 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 09 27 06 18.41 +12 29.6 1.860 2.105 89.5 28.4 20.6 2024 10 07 06 35.94 +12 26.4 1.733 2.072 94.9 28.7 20.4 2024 10 17 06 52.35 +12 23.0 1.611 2.044 100.6 28.6 20.1 2024 10 27 07 07.34 +12 22.8 1.496 2.021 106.7 28.1 19.9 2024 11 06 07 20.53 +12 30.1 1.389 2.002 113.5 27.0 19.7 2024 11 16 07 31.51 +12 50.1 1.291 1.988 120.8 25.3 19.5 2024 11 26 07 39.94 +13 27.5 1.205 1.980 128.9 22.8 19.4 2024 12 06 07 45.47 +14 27.0 1.131 1.976 137.9 19.5 19.2 2024 12 16 07 47.96 +15 50.8 1.074 1.978 147.8 15.4 19.1 2024 12 26 07 47.62 +17 37.2 1.036 1.984 158.5 10.5 19.1 2025 01 05 07 45.01 +19 40.1 1.021 1.996 169.8 5.0 19.0 2025 01 15 07 41.25 +21 48.6 1.030 2.013 178.6 0.7 19.1 2025 01 25 07 37.68 +23 50.8 1.063 2.035 167.1 6.2 19.2 2025 02 04 07 35.57 +25 36.8 1.121 2.061 156.1 11.2 19.4 2025 02 14 07 35.90 +27 00.7 1.200 2.092 145.8 15.4 19.6 2025 02 24 07 39.09 +28 01.1 1.298 2.126 136.2 18.8 19.8 2025 03 06 07 45.16 +28 38.9 1.413 2.164 127.4 21.4 20.1 2025 03 16 07 53.85 +28 56.1 1.542 2.206 119.3 23.2 20.4 2025 03 26 08 04.70 +28 55.2 1.681 2.251 111.8 24.3 20.7 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 October 19 (CBET 5460) Daniel W. E. Green