Electronic Telegram No. 5208 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 C/2023 A1 (LEONARD) G. J. Leonard reports the discovery of another comet in CCD exposures taken on Jan. 9 UT (discovery observations tabulated below) with the Mt. Lemmon Survey's 1.5-m reflector northeast of Tucson. Leonard reported a condensed coma 10" across with a possible short tail about 6" long in p.a. 340 degrees in four 30-s co-added images. 2023 UT R.A. (2000) Decl. Mag. Observer Jan. 9.54101 15 47 08.67 +51 52 42.1 18.9 Leonard 9.54616 15 47 08.54 +51 52 48.9 18.6 " 9.55132 15 47 08.40 +51 52 55.7 18.8 " 9.55648 15 47 08.28 +51 53 02.7 18.6 " After the comet was posted on the Minor Planet Center's PCCP webpage, other CCD astrometrists have commented on the cometary nature. F. Kugel found a 13" tail in p.a. 315 degrees on nine 120-s unfiltered CCD exposures taken with a 0.4-m f/2.8 reflector at Dauban, France, on Jan. 14.2 UT; the magnitude was 18.8-18.9 in an aperture of radius 4".2 (five pixels). Twelve stacked 60-s exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) on Jan. 21.57 with a 0.61-m f/6.5 astrograph located at the Sierra Remote Observatory near Auberry, CA, USA, show a strongly condensed, fuzzy coma 10" in diameter and no tail; the magnitude was 18.5 as measured within a circular aperture of radius 5".0. The available astrometry appears on MPEC 2023-B66. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 81 observations spanning 2023 Jan. 9-22 (mean residual 0".5). T = 2023 Mar. 18.75121 TT Peri. = 159.24533 Node = 318.24719 2000.0 q = 1.8359246 AU Incl. = 94.80997 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 14.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2022 12 07 15 43.00 +45 31.2 2.370 2.232 69.9 24.5 18.7 2022 12 12 15 44.78 +45 51.7 2.295 2.198 71.9 25.2 18.5 2022 12 17 15 46.36 +46 23.1 2.217 2.165 74.1 25.9 18.4 2022 12 22 15 47.63 +47 06.4 2.136 2.133 76.5 26.6 18.3 2022 12 27 15 48.47 +48 02.8 2.052 2.103 79.2 27.3 18.1 2023 01 01 15 48.72 +49 13.7 1.966 2.074 82.1 28.0 18.0 2023 01 06 15 48.17 +50 40.6 1.879 2.046 85.2 28.6 17.9 2023 01 11 15 46.53 +52 25.1 1.790 2.019 88.4 29.1 17.7 2023 01 16 15 43.36 +54 29.2 1.702 1.994 91.9 29.5 17.6 2023 01 21 15 38.02 +56 54.3 1.616 1.971 95.5 29.8 17.4 2023 01 26 15 29.46 +59 41.4 1.532 1.949 99.2 29.9 17.2 2023 01 31 15 15.95 +62 49.4 1.453 1.929 102.9 29.9 17.1 2023 02 05 14 54.59 +66 13.5 1.380 1.910 106.5 29.6 16.9 2023 02 10 14 20.35 +69 40.5 1.316 1.894 109.9 29.3 16.8 2023 02 15 13 25.70 +72 40.4 1.262 1.880 112.8 29.0 16.7 2023 02 20 12 05.81 +74 17.1 1.222 1.867 114.8 28.7 16.6 2023 02 25 10 34.91 +73 29.1 1.197 1.857 115.9 28.7 16.5 2023 03 02 09 20.68 +70 13.7 1.189 1.848 115.7 28.9 16.5 2023 03 07 08 31.61 +65 24.7 1.198 1.842 114.2 29.4 16.5 2023 03 12 08 01.09 +59 54.7 1.224 1.838 111.6 30.2 16.6 2023 03 17 07 42.05 +54 17.4 1.266 1.836 108.0 31.0 16.6 2023 03 22 07 30.07 +48 51.9 1.322 1.836 103.9 31.8 16.7 2023 03 27 07 22.59 +43 48.3 1.390 1.839 99.4 32.4 16.8 2023 04 01 07 18.09 +39 10.9 1.468 1.844 94.8 32.7 17.0 2023 04 06 07 15.64 +35 00.2 1.554 1.850 90.2 32.7 17.1 2023 04 11 07 14.66 +31 14.6 1.645 1.859 85.6 32.5 17.2 2023 04 16 07 14.76 +27 51.8 1.741 1.870 81.1 32.0 17.4 2023 04 21 07 15.69 +24 49.1 1.839 1.884 76.8 31.3 17.5 2023 04 26 07 17.25 +22 03.7 1.938 1.899 72.6 30.4 17.7 2023 05 01 07 19.32 +19 33.0 2.037 1.916 68.6 29.3 17.8 2023 05 06 07 21.77 +17 14.8 2.136 1.934 64.7 28.1 17.9 2023 05 11 07 24.55 +15 07.0 2.234 1.955 61.0 26.9 18.1 2023 05 16 07 27.58 +13 08.0 2.329 1.977 57.4 25.5 18.2 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2023 CBAT 2023 January 23 (CBET 5208) Daniel W. E. Green