Electronic Telegram No. 5588 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 T6 = P/2007 C2 (CATALINA) On 2024 Dec. 8, S. Nakano forwarded a report from T. Kobayashi, who had identified apparently asteroidal recovery observations of comet P/2007 C2 (cf. IAUC 8806) in the Minor Planet Center's "isolated tracklet file" (which is accessible publicly) that were made at Mt. Lemmon (2024 Oct. 23) and with the 2.25-m Bok reflector at Kitt Peak (2024 Oct. 28), with that astrometry tabulated below). 2024 UT R.A. (2000) Decl. Mag. Oct. 23.20710 1 03 45.06 +17 57 32.7 21.7 23.21270 1 03 44.95 +17 57 30.7 21.3 23.21828 1 03 44.77 +17 57 29.9 21.7 23.22386 1 03 44.55 +17 57 28.8 22.1 28.31354 1 01 16.82 +17 38 17.7 21.4 28.31916 1 01 16.65 +17 38 16.3 21.8 28.32477 1 01 16.48 +17 38 15.1 21.5 28.33037 1 01 16.33 +17 38 13.6 21.7 Then on 2025 July 26, R. Weryk (Department of Physics and Astronomy, University of Western Ontario) reported the discovery of a possible new comet (mag 21.1-21.2) in four 45-s w-band survey images taken with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala, HI, USA, in 1".2 seeing -- noting a condensed head of size 1".9 (full-width-at-half-maximum) with possible point-spread-function asymmetry along the direction of motion. Weryk added that the MPC moved his object off of the PCCP soon after his posting there, with a linkage to P/2007 C2 given at the MPC website. The available astrometry appears on MPEC 2025-P121. The designation P/2024 T6 was assigned by the MPC because of additional Pan-STARRS1 astrometry from 2024 Oct. 3.5 UT (magnitude then given as 21.8-22.2) and 2024 Oct. 13.5 (mag 22.0), and Pan-STARRS2 observations on 2024 Oct. 11.3 (mag 22.0-22.1) that were sent by Weryk to the MPC on 2025 July 26 after he identified earlier observations after his accidental 2025 July 26 recovery. (The resultant recovery designation therefore should have been P/2024 U3.) The residuals for the recovery observations were +7'.8 in R.A. and +3'.1 in Decl. from the prediction on NK 1630 (and in the ICQ Comet Handbook 2023), with a corresponding correction of Delta(T) = -1.11 days. An earlier linked orbit by Nakano (Central Bureau) was posted on NK 5353 (not including the 2025 observations). The following linked orbital elements by S. Nakano are from 319 observations spanning 2006 Oct. 19-2025 July 28 (mean residual 0".7). The comet passed 1.64 AU from Saturn on 2020 Jan. 11 and will pass 1.35 AU from Jupiter on 2027 Mar. 18 UT. Epoch = 2007 Sept.17.0 TT T = 2007 Sept. 4.63182 TT Peri. = 179.46439 e = 0.4621827 Node = 276.11807 2000.0 q = 3.7794410 AU Incl. = 8.67490 a = 7.0273698 AU n = 0.05290721 P = 18.63 years Epoch = 2026 Mar. 21.0 TT T = 2026 Mar. 19.54847 TT Peri. = 180.05551 e = 0.4765672 Node = 275.21091 2000.0 q = 3.6930077 AU Incl. = 8.60138 a = 7.0553618 AU n = 0.05259266 P = 18.74 years Epoch = 2044 Apr. 15.0 TT T = 2044 Mar. 27.85770 TT Peri. = 180.25143 e = 0.4722502 Node = 271.89980 2000.0 q = 3.6385164 AU Incl. = 8.60455 a = 6.8943967 AU n = 0.05444521 P = 18.10 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 11.0 and 2.5n = 10 for the magnitudes (i.e., about a magnitude fainter than at the 2007 apparition). Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2025 07 24 04 25.80 +26 24.7 4.509 3.969 52.2 11.7 20.3 2025 08 03 04 37.09 +26 45.7 4.370 3.948 59.2 12.8 20.2 2025 08 13 04 47.75 +27 02.9 4.222 3.927 66.3 13.7 20.1 2025 08 23 04 57.62 +27 16.6 4.068 3.907 73.7 14.4 20.0 2025 09 02 05 06.52 +27 26.9 3.909 3.888 81.4 14.9 19.9 2025 09 12 05 14.27 +27 34.1 3.749 3.869 89.3 15.1 19.7 2025 09 22 05 20.67 +27 38.3 3.588 3.852 97.6 15.0 19.6 2025 10 02 05 25.52 +27 39.8 3.432 3.835 106.3 14.5 19.5 2025 10 12 05 28.64 +27 38.5 3.283 3.819 115.4 13.6 19.4 2025 10 22 05 29.90 +27 34.3 3.144 3.804 125.1 12.4 19.3 2025 11 01 05 29.22 +27 26.9 3.021 3.790 135.2 10.6 19.2 2025 11 11 05 26.68 +27 15.7 2.917 3.777 145.7 8.5 19.1 2025 11 21 05 22.49 +27 00.2 2.837 3.765 156.6 6.0 19.0 2025 12 01 05 17.06 +26 40.1 2.784 3.753 167.8 3.2 19.0 2025 12 11 05 10.97 +26 15.8 2.759 3.743 176.7 0.9 18.9 2025 12 21 05 04.89 +25 48.2 2.765 3.733 168.2 3.1 18.9 2025 12 31 04 59.49 +25 19.0 2.800 3.725 157.0 5.9 18.9 2026 01 10 04 55.35 +24 50.1 2.862 3.717 145.9 8.5 19.0 2026 01 20 04 52.88 +24 23.5 2.948 3.711 135.2 10.8 19.0 2026 01 30 04 52.31 +24 00.5 3.053 3.705 124.8 12.6 19.1 2026 02 09 04 53.70 +23 41.6 3.174 3.701 115.0 14.0 19.2 2026 02 19 04 57.00 +23 27.0 3.307 3.697 105.6 14.9 19.3 2026 03 01 05 02.09 +23 16.1 3.446 3.695 96.7 15.4 19.4 2026 03 11 05 08.80 +23 07.9 3.589 3.693 88.2 15.6 19.4 2026 03 21 05 16.92 +23 01.6 3.732 3.693 80.1 15.4 19.5 2026 03 31 05 26.29 +22 55.8 3.872 3.694 72.3 14.9 19.6 2026 04 10 05 36.71 +22 49.5 4.008 3.695 64.9 14.2 19.7 2026 04 20 05 48.02 +22 41.7 4.137 3.698 57.7 13.3 19.8 2026 04 30 06 00.05 +22 31.6 4.257 3.702 50.7 12.2 19.8 2026 05 10 06 12.67 +22 18.3 4.367 3.707 43.9 10.9 19.9 2026 05 20 06 25.75 +22 01.3 4.466 3.712 37.3 9.5 19.9 2026 09 17 09 02.76 +13 06.4 4.579 3.858 39.6 9.6 20.2 2026 09 27 09 13.44 +12 02.9 4.496 3.876 46.6 10.8 20.1 2026 10 07 09 23.38 +10 59.1 4.402 3.895 53.7 11.9 20.1 2026 10 17 09 32.48 +09 56.1 4.296 3.914 61.2 12.9 20.1 2026 10 27 09 40.63 +08 54.9 4.183 3.935 68.8 13.6 20.1 2026 11 06 09 47.72 +07 56.4 4.062 3.956 76.8 14.1 20.0 2026 11 16 09 53.61 +07 01.8 3.937 3.977 85.2 14.3 20.0 2026 11 26 09 58.18 +06 12.2 3.810 4.000 93.9 14.3 19.9 2026 12 06 10 01.30 +05 28.9 3.686 4.023 103.0 13.8 19.9 2026 12 16 10 02.88 +04 53.1 3.568 4.047 112.5 13.0 19.8 2026 12 26 10 02.87 +04 25.7 3.460 4.072 122.4 11.8 19.8 2027 01 05 10 01.28 +04 07.7 3.366 4.097 132.6 10.2 19.8 2027 01 15 09 58.24 +03 59.4 3.293 4.123 143.2 8.2 19.7 2027 01 25 09 53.99 +04 00.5 3.242 4.149 153.9 6.0 19.7 2027 02 04 09 48.89 +04 10.1 3.219 4.176 164.1 3.7 19.7 2027 02 14 09 43.39 +04 26.5 3.225 4.203 171.1 2.1 19.8 2027 02 24 09 38.01 +04 47.3 3.261 4.231 167.0 3.0 19.8 2027 03 06 09 33.20 +05 10.2 3.327 4.260 157.4 5.1 19.9 2027 03 16 09 29.38 +05 32.5 3.420 4.289 147.0 7.3 20.0 2027 03 26 09 26.83 +05 52.1 3.537 4.318 136.7 9.1 20.1 2027 04 05 09 25.69 +06 07.4 3.675 4.348 126.7 10.6 20.2 2027 04 15 09 26.01 +06 17.2 3.829 4.378 117.1 11.8 20.3 2027 04 25 09 27.76 +06 20.9 3.995 4.408 107.8 12.5 20.5 2027 05 05 09 30.82 +06 18.0 4.169 4.439 99.0 13.0 20.6 2027 05 15 09 35.07 +06 08.7 4.347 4.471 90.5 13.1 20.7 2027 05 25 09 40.35 +05 52.9 4.526 4.502 82.2 12.9 20.8 2027 06 04 09 46.52 +05 30.9 4.702 4.534 74.3 12.4 20.9 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 August 9 (CBET 5588) Daniel W. E. Green