Electronic Telegram No. 5466 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 S3 = P/2010 A3 (HILL) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reported the discovery of another comet in images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on Oct. 7.6 UT (discovery observations tabulated below), and he put the object on the Minor Planet Center's PCCP webpage. Four stacked 45-s w-band survey images taken in 1".3-1".5 seeing show a very condensed head of size 1".6 (full-width-at- half-maximum) with a broad 6"-long tail spanning p.a. 250-290 degrees. 2024 UT R.A. (2000) Decl. Mag. Oct. 7.55722 3 06 32.35 + 4 18 59.3 20.2 7.57040 3 06 32.08 + 4 18 59.9 20.3 7.58366 3 06 31.83 + 4 19 00.3 20.2 7.59644 3 06 31.57 + 4 19 00.9 20.4 Weryk then identified apparently asteroidal unlinked observations of this comet in the MPC's "isolated tracklet file" that were obtained on Sept. 11.4 UT with the Mt. Lemmon 1.5-m reflector (mag 20.6-21.1) and on Sept. 14.6 with the Pan-STARRS1 reflector (mag 21.1-21.3). These observations are tabulated below (and were not included in MPEC 2024-U42 with other astrometry). 2024 UT R.A. (2000) Decl. Mag. Sept.11.37922 3 04 49.64 + 4 01 13.7 21.1 11.38441 3 04 49.76 + 4 01 14.2 21.3 11.38960 3 04 49.87 + 4 01 14.4 20.6 11.39478 3 04 49.97 + 4 01 14.7 21.1 14.57432 3 05 56.71 + 4 04 07.4 21.1 14.58606 3 05 56.91 + 4 04 08.1 21.2 14.60623 3 05 57.24 + 4 04 08.9 21.3 This led Weryk to identify additional images of the comet in observations obtained with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala from Sept. 26.59-26.62 (at mag 20.2-20.5) and Oct. 3.42-3.46 UT (mag 20.0- 20.1). The best of four 45-s w-band survey images from Sept. 26 was taken in 0".9 seeing and shows a very condensed head of size 1".0 (FWHM) with a possible point-spread-function asymmetry suggesting a tail toward the west. Four stacked 45-s w-band survey images taken on Oct. 3 in 1".2-1".4 seeing show a very condensed head of size 1".5 (FWHM) with a broad, 5"-long tail spanning p.a. 250-290 degrees. This comet was then identified at the Minor Planet Center as being an accidental recovery of comet P/2010 A3 (cf. IAUCs 9106, 9108). The residuals for the recovery observations are +0.44 deg in R.A. and +0.23 deg in Decl. from the prediction in NK 1956, with a corresponding correction of Delta(T) = -1.05 days. The following linked orbital elements by S. Nakano (Central Bureau) are from 413 observations spanning 2009 Oct. 14-2024 Oct. 22 (mean residual 0".5). The comet passed 2.26 AU from Saturn on 2020 July 31 UT. Epoch = 1995 May 3.0 TT T = 1995 May 21.13513 TT Peri. = 41.21308 e = 0.7320813 Node = 65.04360 2000.0 q = 1.6234935 AU Incl. = 15.04234 a = 6.0596507 AU n = 0.06607432 P = 14.92 years Epoch = 2010 Mar. 25.0 TT T = 2010 Apr. 3.68211 TT Peri. = 41.28293 e = 0.7322146 Node = 64.82894 2000.0 q = 1.6218162 AU Incl. = 15.02815 a = 6.0564035 AU n = 0.06612746 P = 14.90 years Epoch = 2025 Mar. 26.0 TT T = 2025 Mar. 10.28383 TT Peri. = 42.24753 e = 0.7343306 Node = 63.58745 2000.0 q = 1.6210473 AU Incl. = 14.81457 a = 6.1017464 AU n = 0.06539173 P = 15.07 years Epoch = 2040 Mar. 27.0 TT T = 2040 Mar. 21.87975 TT Peri. = 42.36701 e = 0.7347048 Node = 63.59349 2000.0 q = 1.6122462 AU Incl. = 14.81028 a = 6.0771776 AU n = 0.06578868 P = 14.98 years Epoch = 2054 Sept.10.0 TT T = 2054 Sept.23.46411 TT Peri. = 42.57752 e = 0.7389921 Node = 61.97057 2000.0 q = 1.5496557 AU Incl. = 14.70010 a = 5.9371974 AU n = 0.06812897 P = 14.47 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 14.5 and 2.5n = 10 for the magnitudes. This is about 2 mag fainter than in 2009-2010. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 09 27 03 08.02 +04 12.6 1.588 2.418 136.7 16.5 19.3 2024 10 07 03 06.70 +04 18.6 1.447 2.345 146.2 13.7 19.0 2024 10 17 03 02.49 +04 28.2 1.325 2.273 156.1 10.2 18.7 2024 10 27 02 55.52 +04 46.2 1.226 2.202 165.4 6.5 18.4 2024 11 06 02 46.32 +05 17.9 1.151 2.133 169.3 4.9 18.1 2024 11 16 02 36.05 +06 08.2 1.101 2.066 162.6 8.2 17.9 2024 11 26 02 26.18 +07 20.1 1.076 2.002 152.0 13.4 17.7 2024 12 06 02 18.28 +08 54.3 1.073 1.941 141.1 18.6 17.5 2024 12 16 02 13.64 +10 49.3 1.088 1.883 130.6 23.4 17.4 2024 12 26 02 12.98 +13 02.0 1.116 1.829 121.1 27.4 17.4 2025 01 05 02 16.63 +15 29.0 1.155 1.780 112.5 30.7 17.3 2025 01 15 02 24.59 +18 06.5 1.200 1.737 105.0 33.2 17.3 2025 01 25 02 36.66 +20 50.3 1.249 1.699 98.4 35.0 17.3 2025 02 04 02 52.66 +23 36.0 1.302 1.669 92.6 36.2 17.3 2025 02 14 03 12.37 +26 18.6 1.358 1.645 87.6 36.8 17.3 2025 02 24 03 35.57 +28 52.3 1.415 1.629 83.3 37.1 17.4 2025 03 06 04 02.02 +31 11.1 1.476 1.622 79.5 37.0 17.4 2025 03 16 04 31.39 +33 08.5 1.541 1.622 76.2 36.5 17.5 2025 03 26 05 03.18 +34 38.8 1.610 1.631 73.2 35.8 17.7 2025 04 05 05 36.79 +35 37.2 1.685 1.648 70.5 34.9 17.8 2025 04 15 06 11.42 +36 00.8 1.766 1.673 68.0 33.8 18.0 2025 04 25 06 46.22 +35 49.2 1.854 1.704 65.6 32.5 18.2 2025 05 05 07 20.43 +35 04.2 1.949 1.743 63.1 31.1 18.4 2025 05 15 07 53.41 +33 49.5 2.051 1.787 60.6 29.5 18.6 2025 05 25 08 24.74 +32 10.3 2.161 1.837 58.0 27.9 18.8 2025 06 04 08 54.24 +30 11.8 2.276 1.891 55.2 26.1 19.1 2025 06 14 09 21.85 +27 59.3 2.398 1.949 52.2 24.3 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 October 23 (CBET 5466) Daniel W. E. Green