Electronic Telegram No. 5590 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/2025 M4 = P/2010 U1 (BOATTINI) On July 28, T. Oribe reported his recovery of comet P/2010 U1 (cf. IAUC 9174) as a stellar object in CCD images obtained with a 1.03-m reflector (+ L filter) at Saji, Japan (recovery astrometry tabulated below). On Jan. 27, the seeing was worse, making measurements difficult. 2025 UT R.A. (2000) Decl. Mag. Observer July 24.69642 22 06 17.64 - 4 00 43.5 21.7 Oribe 24.70200 22 06 17.52 - 4 00 43.5 " 24.70758 22 06 17.41 - 4 00 44.3 " 24.71316 22 06 17.26 - 4 00 43.8 " 27.62656 22 05 13.03 - 4 02 17.4 21.5 " 27.63214 22 05 12.81 - 4 02 17.5 " 27.63772 22 05 12.74 - 4 02 17.5 " 27.64329 22 05 12.67 - 4 02 17.5 " On July 29, R. Weryk (Department of Physics and Astronomy, University of Western Ontario), not knowing of Oribe's recovery, reported the discovery of an apparently new comet in images obtained with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala (observations tabulated below), in which he noted that four 45-s w-band survey images taken in 0".9-1".0 seeing showed a condensed head of size 1".3 (full-width-at-half-maximum) with a straight 6" tail in p.a. 240 degrees. 2025 UT R.A. (2000) Decl. Mag. July 29.48982 22 04 29.73 - 4 03 33.1 21.5 29.50135 22 04 29.45 - 4 03 33.6 21.7 29.51289 22 04 29.17 - 4 03 34.1 21.5 29.52444 22 04 28.89 - 4 03 34.6 21.4 After Weryk noticed that the Minor Planet Center had found this to be an accidental recovery of P/2010 U1, he identified pre-recovery astrometry with the same telescope from June 20 and July 23 (tabulated below). 2025 UT R.A. (2000) Decl. Mag. June 20.55099 22 12 36.72 - 4 26 05.3 21.6 20.56373 22 12 36.70 - 4 26 04.0 21.8 20.57650 22 12 36.69 - 4 26 02.5 21.8 20.58930 22 12 36.70 - 4 26 01.0 21.7 July 23.48160 22 06 43.26 - 4 00 14.5 21.1 23.49309 22 06 43.02 - 4 00 14.5 21.3 23.50463 22 06 42.78 - 4 00 14.6 21.6 23.51619 22 06 42.51 - 4 00 14.7 21.5 The MPC inadvertently gave this a designation for the June pre-recovery observations (P/2024 M4) on MPEC 2025-P122, when it should have assigned the designation P/2025 O1. The residuals of the recovery observations were +4'.4 in R.A. and +2'.1 in Decl. from the prediction on NK 2398 (and in the ICQ's 2025 Comet Handbook) with a corresponding correction of Delta(T) = -0.72 day. The following linked orbital elements by S. Nakano (Central Bureau) are from 131 observations spanning 2009 Sept. 17-2025 July 29 (mean residual 0".5). The comet passed 0.62 AU from Jupiter in 1973 Nov. and 2.04 AU from Jupiter on 2014 Sept. 2 UT. Epoch = 2010 Mar. 25.0 TT T = 2010 Mar. 27.88190 TT Peri. = 88.82290 e = 0.2633949 Node = 281.50232 2000.0 q = 4.9027747 AU Incl. = 8.24329 a = 6.6559069 AU n = 0.05739753 P = 17.17 years Epoch = 2026 Aug. 28.0 TT T = 2026 Sept. 9.06817 TT Peri. = 86.68406 e = 0.2475839 Node = 280.65090 2000.0 q = 4.8752857 AU Incl. = 8.22682 a = 6.4795074 AU n = 0.05975732 P = 16.49 years Epoch = 2043 Jan. 31.0 TT T = 2043 Jan. 21.12475 TT Peri. = 85.50232 e = 0.2472668 Node = 280.44008 2000.0 q = 4.8796817 AU Incl. = 8.22708 a = 6.4826176 AU n = 0.05971432 P = 16.50 years Epoch = 2059 July 6.0 TT T = 2059 July 18.13330 TT Peri. = 84.16358 e = 0.2565365 Node = 279.67268 2000.0 q = 4.9011540 AU Incl. = 8.24600 a = 6.5923267 AU n = 0.05822989 P = 16.93 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 12.0 and 2.5n = 7.5 for the magnitudes. The comet seems to be a couple of magnitudes fainter than in 2009-2010, but it's possible that the comet could be brighter than these ephemeris magnitudes near perihelion. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2025 07 24 22 06.54 -04 00.4 4.232 5.122 148.1 6.0 20.5 2025 08 03 22 02.65 -04 07.5 4.156 5.111 158.1 4.2 20.4 2025 08 13 21 58.19 -04 20.3 4.106 5.100 167.5 2.5 20.4 2025 08 23 21 53.46 -04 37.6 4.085 5.089 172.3 1.5 20.4 2025 09 02 21 48.81 -04 57.8 4.094 5.079 165.9 2.8 20.4 2025 09 12 21 44.58 -05 18.9 4.131 5.069 156.2 4.6 20.4 2025 09 22 21 41.09 -05 39.2 4.195 5.058 145.9 6.4 20.4 2025 10 02 21 38.59 -05 57.0 4.284 5.049 135.7 8.0 20.4 2025 10 12 21 37.25 -06 10.9 4.392 5.039 125.6 9.3 20.5 2025 10 22 21 37.17 -06 19.8 4.517 5.030 115.8 10.3 20.5 2025 11 01 21 38.36 -06 22.9 4.653 5.021 106.1 10.9 20.6 2025 11 11 21 40.80 -06 19.9 4.797 5.012 96.8 11.3 20.7 2025 11 21 21 44.40 -06 10.5 4.944 5.003 87.7 11.4 20.7 2026 06 09 00 21.21 +10 34.4 5.160 4.888 69.0 11.2 20.7 2026 06 19 00 26.57 +11 24.9 5.015 4.886 76.9 11.7 20.7 2026 06 29 00 31.03 +12 10.9 4.865 4.883 85.0 12.0 20.6 2026 07 09 00 34.52 +12 51.7 4.714 4.881 93.4 12.0 20.5 2026 07 19 00 36.92 +13 26.5 4.565 4.879 102.1 11.8 20.5 2026 07 29 00 38.15 +13 54.2 4.421 4.878 111.0 11.2 20.4 2026 08 08 00 38.16 +14 14.2 4.286 4.877 120.3 10.3 20.3 2026 08 18 00 36.95 +14 25.5 4.165 4.876 129.9 9.2 20.3 2026 08 28 00 34.58 +14 27.7 4.061 4.876 139.7 7.7 20.2 2026 09 07 00 31.21 +14 20.6 3.979 4.875 149.6 6.0 20.2 2026 09 17 00 27.06 +14 04.6 3.922 4.875 159.3 4.2 20.1 2026 09 27 00 22.45 +13 40.8 3.892 4.876 167.5 2.5 20.1 2026 10 07 00 17.75 +13 11.1 3.892 4.876 168.9 2.3 20.1 2026 10 17 00 13.34 +12 37.7 3.921 4.878 161.8 3.7 20.1 2026 10 27 00 09.59 +12 03.6 3.978 4.879 152.1 5.5 20.2 2026 11 06 00 06.78 +11 31.4 4.062 4.880 141.9 7.2 20.2 2026 11 16 00 05.11 +11 03.4 4.169 4.882 131.6 8.7 20.3 2026 11 26 00 04.72 +10 41.6 4.295 4.885 121.5 9.9 20.3 2026 12 06 00 05.62 +10 27.3 4.436 4.887 111.7 10.8 20.4 2026 12 16 00 07.81 +10 21.0 4.587 4.890 102.1 11.3 20.5 2026 12 26 00 11.20 +10 23.0 4.745 4.893 92.9 11.6 20.6 2027 01 05 00 15.69 +10 33.1 4.903 4.897 83.9 11.5 20.6 2027 01 15 00 21.18 +10 50.8 5.060 4.900 75.1 11.2 20.7 2027 01 25 00 27.53 +11 15.3 5.211 4.904 66.6 10.6 20.8 2027 02 04 00 34.63 +11 45.9 5.354 4.909 58.3 9.8 20.8 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 August 12 (CBET 5590) Daniel W. E. Green