Electronic Telegram No. 5433 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 C6 = P/2019 M2 (ATLAS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the recovery of comet P/2019 M2 (cf. CBET 4651) as an apparently stellar object in CCD images obtained on 2024 Feb. 4 with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala. Weryk identified additional apparently stellar images of the comet taken with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on Feb. 15.4, Mar. 1.4, Mar. 31.3, and Apr. 4 UT (observations tabulated below; cf. MPEC 2024-Q25). 2024 UT R.A. (2000) Decl. Mag. Feb. 4.52396 11 02 35.68 - 3 29 20.4 22.4 4.54619 11 02 34.68 - 3 29 22.8 21.9 15.39979 10 53 07.94 - 3 38 53.0 22.0 15.42304 10 53 06.48 - 3 38 52.9 22.1 15.43467 10 53 05.74 - 3 38 52.8 21.9 Mar. 1.38974 10 35 42.29 - 3 19 54.2 21.6 1.40211 10 35 41.33 - 3 19 52.5 21.8 1.41449 10 35 40.34 - 3 19 50.6 21.8 1.42624 10 35 39.42 - 3 19 49.0 21.4 31.27315 9 59 01.35 - 1 23 17.9 22.2 31.28563 9 59 00.60 - 1 23 14.5 21.6 31.29809 9 58 59.83 - 1 23 11.4 22.2 Apr. 4.31644 9 55 17.98 - 1 05 55.5 22.2 4.36512 9 55 15.36 - 1 05 43.4 22.2 4.37718 9 55 14.73 - 1 05 40.1 21.7 The residuals for the recovery observations were -37" in R.A. and +24" in Decl. from the prediction in NK 3926, with a corresponding correction of Delta(T) = +0.04 day. The following linked orbital elements by S. Nakano (Central Bureau) are from 359 observations spanning 2019 Feb. 19-2024 Apr. 4 (mean residual 0".4). The comet passed 0.66 AU from Jupiter on 1990 Jan. 11 UT, and it will pass 0.84 AU from Jupiter on 2037 May 15 UT. The suggested identity with comet D/1884 O1 (cf. CBET 4657) does not appear to be correct, as Nakano notes that the linkage below yields T = 1882 Nov. 1.9 TT, q = 1.0204 AU, e = 0.6631, Peri. = 302.56 deg, Node = 335.86 deg, i = 7.58 deg. Epoch = 2003 Aug. 29.0 TT T = 2003 Sept. 2.04476 TT Peri. = 332.52167 e = 0.6475162 Node = 307.65974 2000.0 q = 1.0682693 AU Incl. = 12.25606 a = 3.0306907 AU n = 0.18680635 P = 5.28 years Epoch = 2008 Nov. 30.0 TT T = 2008 Dec. 10.34001 TT Peri. = 332.59398 e = 0.6482629 Node = 307.60898 2000.0 q = 1.0649593 AU Incl. = 12.27256 a = 3.0277137 AU n = 0.18708194 P = 5.27 years Epoch = 2014 Mar. 4.0 TT T = 2014 Mar. 17.47923 TT Peri. = 332.52893 e = 0.6479160 Node = 307.63521 2000.0 q = 1.0665361 AU Incl. = 12.26763 a = 3.0292088 AU n = 0.18694345 P = 5.27 years Epoch = 2019 June 6.0 TT T = 2019 June 22.66928 TT Peri. = 332.51891 e = 0.6486817 Node = 307.60604 2000.0 q = 1.0633976 AU Incl. = 12.28094 a = 3.0268783 AU n = 0.18715939 P = 5.27 years Epoch = 2024 Oct. 17.0 TT T = 2024 Sept.28.18682 TT Peri. = 332.52332 e = 0.6472802 Node = 307.60773 2000.0 q = 1.0687606 AU Incl. = 12.26631 a = 3.0300554 AU n = 0.18686511 P = 5.27 years Epoch = 2030 Jan. 19.0 TT T = 2030 Jan. 7.35362 TT Peri. = 332.51747 e = 0.6455313 Node = 307.57280 2000.0 q = 1.0757315 AU Incl. = 12.25662 a = 3.0347719 AU n = 0.18642965 P = 5.29 years Epoch = 2035 Apr. 23.0 TT T = 2035 Apr. 25.57414 TT Peri. = 332.66650 e = 0.6451836 Node = 307.49726 2000.0 q = 1.0774429 AU Incl. = 12.26421 a = 3.0366208 AU n = 0.18625941 P = 5.29 years Epoch = 2040 Sept. 3.0 TT T = 2040 Sept.17.97840 TT Peri. = 336.88552 e = 0.6252021 Node = 303.65933 2000.0 q = 1.1592925 AU Incl. = 13.09930 a = 3.0931136 AU n = 0.18118001 P = 5.44 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 19.0 and 2.5n = 8 for the magnitudes. This comet shows an unsual brightness variation, with the current apparition running 2-3 magnitudes brighter than in 2019, though the 2024 observations are also about 1 AU further from the sun pre- perihelion than in 2019. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 07 29 11 46.09 -09 28.1 1.617 1.331 55.2 38.8 21.0 2024 08 08 12 12.79 -11 50.0 1.584 1.261 52.7 39.8 20.8 2024 08 18 12 42.67 -14 20.2 1.546 1.199 50.8 40.9 20.6 2024 08 28 13 16.07 -16 52.5 1.504 1.146 49.6 42.2 20.4 2024 09 07 13 53.34 -19 18.2 1.463 1.105 49.0 43.5 20.2 2024 09 17 14 34.63 -21 25.4 1.426 1.079 49.0 44.7 20.0 2024 09 27 15 19.70 -23 00.4 1.397 1.069 49.6 45.6 20.0 2024 10 07 16 07.83 -23 49.9 1.381 1.075 50.7 46.0 20.0 2024 10 17 16 57.61 -23 44.2 1.381 1.098 52.0 45.7 20.0 2024 10 27 17 47.29 -22 41.1 1.401 1.135 53.4 44.6 20.2 2024 11 06 18 35.20 -20 46.8 1.443 1.185 54.5 42.9 20.4 2024 11 16 19 20.12 -18 13.1 1.505 1.245 55.3 40.8 20.7 2024 11 26 20 01.45 -15 14.3 1.588 1.313 55.6 38.3 21.0 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 August 20 (CBET 5433) Daniel W. E. Green