Electronic Telegram No. 5277 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/2023 M3 = P/2015 T3 (PANSTARRS) Jacqueline B. Fazekas, Lunar and Planetary Laboratory, University of Arizona, reported the discovery of a comet on CCD images obtained with the Mt. Lemmon Survey's 1.5-m reflector on June 26 (discovery observations tabulated below). The comet showed a condensed coma of size 12" with a broad 3"-long tail spanning p.a. 220-250 degrees. 2023 UT R.A. (2000) Decl. Mag. Observer June 26.42483 0 26 58.95 - 6 04 48.1 19.1 Fazekas 26.43005 0 26 59.42 - 6 04 47.5 18.8 " 26.43527 0 26 59.86 - 6 04 46.6 19.0 " 26.44051 0 27 00.29 - 6 04 46.3 19.2 " Pre-discovery Catalina Sky Survey observations made with the 0.7-m reflector by D. Rankin on June 22.45-22.46 UT (and reported later) show a condensed 10" coma of magnitude 18.7-19.6 with no tail. After the comet was posted to the Minor Planet Center's PCCP webpage, other CCD astrometrists also commented on the cometary appearance. L. Buzzi, Varese, Italy, notes that fifty-five stacked 60-s exposures taken on June 29.2 UT by A. Aletti, F. Bellini, G. Galli, and himself with a 0.36-m f/8.4 reflector located at Hakos, Namibia, in good conditions show a diffuse 9" coma of mag 19.3 that is elongated east-west, with a possible faint tail in p.a. about 260 degrees. T. Prystavski (Lviv, Ukraine) writes that eight stacked 60-s exposures obtained on June 29.34 UT remotely with an iTelescope 0.51-m f/6.8 Corrected Dall-Kirkham telescope located in the Rio Hurtado Valley in Chile show a diffuse 0'.3 coma of total mag 18.0. Ten stacked 60-s exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) on June 29.38 with a 0.51-m f/6.8 astrograph also in the Rio Hurtado Valley show a strongly condensed coma 10" in diameter with a fan-like tail 20" long spanning p.a. 225-315 degrees; the magnitude was 18.7 as measured within a circular aperture of radius 5".0. The comet was then identified by M. Suzuki (Kitami, Hokkaido, Japan) as an accidental recovery of comet P/2015 T3 (cf. CBET 4152). The available astrometry appears on MPEC 2023-N18. The residuals for the recovery observations were -0.19 deg in R.A. and -0.05 deg in Decl. from the prediction on NK 4409 (= ICQ Comet Handbook 2023), with a corresponding correction of Delta(T) = +0.58 day. The following linked orbital elements by S. Nakano (Central Bureau) are from 96 observations spanning 2015-2023 (mean residual 0".6). The comet passed 0.63 AU from Jupiter on 2003 Aug. 24 and will pass 0.28 AU from Jupiter on 2025 Dec. 24 UT. Also, the comet passed 3.56 AU from Saturn in 1978 August. Epoch = 2007 Jan. 20.0 TT T = 2007 Jan. 16.36163 TT Peri. = 196.54663 e = 0.4667885 Node = 119.96144 2000.0 q = 2.1538785 AU Incl. = 12.24057 a = 4.0394445 AU n = 0.12140082 P = 8.12 years Epoch = 2015 Feb. 27.0 TT T = 2015 Mar. 10.15371 TT Peri. = 196.60342 e = 0.4650167 Node = 119.89850 2000.0 q = 2.1694469 AU Incl. = 12.22038 a = 4.0551675 AU n = 0.12069544 P = 8.17 years Epoch = 2023 May 16.0 TT T = 2023 May 3.64277 TT Peri. = 196.69154 e = 0.4667373 Node = 119.87132 2000.0 q = 2.1546812 AU Incl. = 12.23680 a = 4.0405625 AU n = 0.12135044 P = 8.12 years Epoch = 2031 Feb. 23.0 TT T = 2031 Feb. 4.36145 TT Peri. = 195.32745 e = 0.4289454 Node = 113.81311 2000.0 q = 2.3079434 AU Incl. = 16.14343 a = 4.0415459 AU n = 0.12130614 P = 8.12 years Epoch = 2039 Apr. 2.0 TT T = 2039 Apr. 1.78621 TT Peri. = 195.52403 e = 0.4277491 Node = 113.76704 2000.0 q = 2.3216470 AU Incl. = 16.11451 a = 4.0570440 AU n = 0.12061171 P = 8.17 years Epoch = 2047 June 19.0 TT T = 2047 May 30.99993 TT Peri. = 195.64939 e = 0.4291187 Node = 113.71163 2000.0 q = 2.3088690 AU Incl. = 16.13242 a = 4.0443940 AU n = 0.12117803 P = 8.13 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 13.5 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2023 06 25 00 24.92 -06 07.4 1.952 2.195 89.6 27.6 18.4 2023 07 05 00 38.68 -05 55.2 1.863 2.211 95.8 27.2 18.3 2023 07 15 00 50.72 -05 59.5 1.778 2.230 102.5 26.4 18.2 2023 07 25 01 00.73 -06 21.6 1.698 2.252 109.6 25.2 18.2 2023 08 04 01 08.41 -07 01.8 1.624 2.276 117.3 23.4 18.1 2023 08 14 01 13.49 -07 59.4 1.561 2.302 125.5 21.0 18.1 2023 08 24 01 15.76 -09 11.6 1.510 2.330 134.2 18.1 18.1 2023 09 03 01 15.20 -10 33.3 1.474 2.360 143.1 14.9 18.1 2023 09 13 01 12.04 -11 57.2 1.458 2.392 151.7 11.5 18.1 2023 09 23 01 06.81 -13 14.4 1.463 2.425 158.5 8.7 18.2 2023 10 03 01 00.39 -14 15.7 1.493 2.460 160.9 7.6 18.3 2023 10 13 00 53.78 -14 54.4 1.547 2.497 157.3 8.9 18.4 2023 10 23 00 47.97 -15 07.1 1.624 2.535 149.9 11.4 18.6 2023 11 02 00 43.75 -14 53.8 1.724 2.574 141.2 14.0 18.8 2023 11 12 00 41.55 -14 17.5 1.843 2.614 132.2 16.3 19.0 2023 11 22 00 41.56 -13 21.9 1.979 2.654 123.4 18.1 19.2 2023 12 02 00 43.73 -12 11.4 2.128 2.696 114.9 19.4 19.4 2023 12 12 00 47.86 -10 49.9 2.287 2.738 106.7 20.1 19.7 2023 12 22 00 53.73 -09 20.5 2.455 2.781 98.8 20.5 19.9 2024 01 01 01 01.08 -07 45.8 2.627 2.825 91.3 20.4 20.1 2024 01 11 01 09.68 -06 08.1 2.801 2.869 83.9 19.9 20.3 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2023 CBAT 2023 July 7 (CBET 5277) Daniel W. E. Green