Electronic Telegram No. 5473 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 OC_2 (PANSTARRS) David J. Tholen, Institute for Astronomy, University of Hawaii, reported on Nov. 8 the discovery of a comet (mag 19.3) in G-band images obtained on Nov. 6.6 UT with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea while attempting to observe the Apollo-type minor planet 2024 OC_2, which had been discovered in July in images obtained with the Pan-STARRS1 and Pan-STARRS2 1.8-m Ritchey-Chretien reflectors at Haleakala, Hawaii (cf. MPEC 2024-P14). Tholen noted a clear tail at least 1' long to the west (p.a. 280 deg); Tholen had to contend with contamination from a galaxy to the north. Because the seeing was "lousy", Tholen thought that the minor planet (predicted to have been 4 mag fainter) may have been too faint to have been detected. Tholen's astrometry is tabulated below. 2024 UT R.A. (2000) Decl. Mag. Nov. 6.62874 11 32 09.54 - 1 26 39.4 19.3 6.63031 11 32 09.69 - 1 26 39.4 19.3 After the comet was posted on the Minor Planet Center's PCCP webpage, H. Sato (Bunkyo-ku, Tokyo, Japan) suggested the identity of Tholen's comet with 2024 OC_2; Sato obtained twelve stacked 20-s CCD exposures remotely with a 0.43-m f/6.8 astrograph located at the Utah Desert Remote Observatory (near Beryl Junction, UT, USA) on Nov. 8.54 UT, which show a moderately condensed, elongated coma of size 6" x 10" with a hint of tail 15" long toward p.a. 280 degrees; the magnitude was 18.7 as measured within a circular aperture of radius 5".7. Following a request by the Central Bureau to R. Weryk (Department of Physics and Astronomy, University of Western Ontario), Weryk reports that four 45-s w-band Pan-STARRS1 survey images taken on July 28.3 UT in 1".1-1".2 seeing do not show cometary appearance, with the head of 2024 OC_2 having a size of 1".2 (full-width-at-half-maximum); the astrometry from these images are tabulated below, along with two additional Pan-STARRS2 observations also from July 28.4 and subsequent Pan-STARRS2 images identified later by Weryk from July 9 (again, the four 45-s g-band survey images on July 9 show no cometary activity). 2024 UT R.A. (2000) Decl. Mag. July 9.35098 17 42 46.38 -11 10 25.3 20.6 9.35957 17 42 44.79 -11 10 25.7 21.5 9.37680 17 42 41.66 -11 10 26.8 21.4 28.29555 16 41 49.24 -12 07 15.2 21.8 28.30747 16 41 46.78 -12 07 18.4 22.0 28.31934 16 41 44.37 -12 07 21.4 22.0 28.33118 16 41 41.93 -12 07 25.0 22.1 28.42531 16 41 22.71 -12 07 50.3 22.0 28.42614 16 41 22.58 -12 07 50.2 21.3 Weryk adds that three 40-s follow-up gri-band images obtained with the CFHT on July 29.3 UT in 0".9 seeing also show only a sharp point-spread function for the head with no tail. A. Hale (Cloudcroft, NM, USA) reports that CCD images obtained on Nov. 12.24-12.25 UT with a 0.35-m f/3 Cassegrain reflector located at Tenerife, Canary Island, show a small, condensed, and clearly diffuse coma with a tail extending initially 0'.2 toward p.a. 275 degrees and then bending toward p.a. 285 degrees for an additional 0'.9. J. Greaves (Northants, UK) writes that the orbital elements of 2024 OC_2 suggest a relationship to the alpha Capricornid meteor shower. The available astrometry appears on MPEC 2024-V174. The following orbital elements by S. Nakano (Central Bureau) are from 37 observations spanning 2024 July 9-Nov. 12 (mean residual 0".6). There are no close approaches to any major planets. Epoch = 2003 July 20.0 TT T = 2003 July 26.83712 TT Peri. = 248.83703 e = 0.7736089 Node = 145.90884 2000.0 q = 0.5946609 AU Incl. = 8.00294 a = 2.6266969 AU n = 0.23152032 P = 4.26 years Epoch = 2007 Oct. 27.0 TT T = 2007 Oct. 30.96636 TT Peri. = 254.58604 e = 0.7800417 Node = 140.38075 2000.0 q = 0.5741687 AU Incl. = 7.82622 a = 2.6103528 AU n = 0.23369815 P = 4.22 years Epoch = 2012 Feb. 3.0 TT T = 2012 Jan. 17.33375 TT Peri. = 254.61613 e = 0.7809552 Node = 140.35101 2000.0 q = 0.5712864 AU Incl. = 7.82790 a = 2.6080798 AU n = 0.23400372 P = 4.21 years Epoch = 2016 Apr. 2.0 TT T = 2016 Apr. 4.46981 TT Peri. = 254.70531 e = 0.7801494 Node = 140.26834 2000.0 q = 0.5737880 AU Incl. = 7.82332 a = 2.6098991 AU n = 0.23375909 P = 4.22 years Epoch = 2020 July 10.0 TT T = 2020 July 6.54752 TT Peri. = 258.45451 e = 0.7736153 Node = 136.68702 2000.0 q = 0.5948346 AU Incl. = 7.67072 a = 2.6275385 AU n = 0.23140911 P = 4.26 years Epoch = 2024 Oct. 17.0 TT T = 2024 Oct. 9.32744 TT Peri. = 258.53874 e = 0.7742545 Node = 136.61810 2000.0 q = 0.5928295 AU Incl. = 7.67127 a = 2.6260964 AU n = 0.23159974 P = 4.26 years Epoch = 2029 Jan. 24.0 TT T = 2029 Jan. 10.16153 TT Peri. = 258.53967 e = 0.7739170 Node = 136.60014 2000.0 q = 0.5938779 AU Incl. = 7.67028 a = 2.6268137 AU n = 0.23150489 P = 4.26 years Epoch = 2033 May 3.0 TT T = 2033 Apr. 16.40012 TT Peri. = 258.87044 e = 0.7719789 Node = 136.27590 2000.0 q = 0.6002194 AU Incl. = 7.65338 a = 2.6322979 AU n = 0.23078178 P = 4.27 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 20.0 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 06 19 18 30.94 -11 16.1 0.825 1.825 164.5 8.5 22.2 2024 06 29 18 10.48 -11 05.4 0.708 1.714 166.8 7.8 21.6 2024 07 09 17 43.81 -11 09.8 0.617 1.600 155.8 15.1 21.0 2024 07 19 17 12.55 -11 31.5 0.550 1.481 140.2 26.0 20.4 2024 07 29 16 39.50 -12 10.4 0.503 1.359 123.4 38.6 19.8 2024 08 08 16 07.25 -13 06.0 0.469 1.233 106.6 52.0 19.3 2024 08 18 15 36.48 -14 15.7 0.440 1.104 90.0 66.5 18.6 2024 08 28 15 04.43 -15 31.1 0.410 0.974 73.2 83.0 18.0 2024 09 07 14 24.49 -16 27.0 0.377 0.847 54.7 104.0 17.2 2024 09 17 13 27.66 -15 51.3 0.354 0.731 32.4 132.5 16.4 2024 09 27 12 17.87 -12 04.6 0.373 0.640 10.5 163.4 15.9 2024 10 07 11 26.35 -06 39.8 0.459 0.595 21.1 142.8 16.1 2024 10 17 11 09.85 -03 02.4 0.596 0.612 34.9 111.3 16.7 2024 10 27 11 16.11 -01 37.3 0.739 0.684 43.5 88.5 17.7 2024 11 06 11 31.11 -01 26.0 0.863 0.791 49.9 73.5 18.7 2024 11 16 11 47.74 -01 43.6 0.960 0.915 55.9 63.6 19.5 2024 11 26 12 03.20 -02 06.5 1.029 1.044 62.3 56.9 20.2 2024 12 06 12 16.28 -02 21.7 1.073 1.173 69.3 51.8 20.8 2024 12 16 12 26.36 -02 21.4 1.096 1.300 77.2 47.6 21.3 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 November 13 (CBET 5473) Daniel W. E. Green