Electronic Telegram No. 5316 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 V5 (LEONARD) Gregory J. Leonard, Lunar and Planetary Laboratory, University of Arizona, reports his discovery of another comet on images obtained on Nov. 6 UT with the Catalina Sky Survey's 0.68-m Schmidt telescope (discovery observations tabulated below). The comet showed a moderately condensed coma 10" across with no apparent tail in four co-added 30-s exposures. 2023 UT R.A. (2000) Decl. Mag. Observer Nov. 6.14346 22 17 57.49 - 8 47 42.1 17.4 Leonard 6.14852 22 17 51.86 - 8 46 39.7 17.7 " 6.15358 22 17 46.19 - 8 45 38.3 " 6.15865 22 17 40.47 - 8 44 37.0 17.8 " After the comet was posted to the Minor Planet Center's PCCP webpage, other CCD astrometrists have also commented on the cometary appearance. A. C. Gilmore and P. M. Kilmartin write that images taken on Nov. 6.4 UT with the Mount John University Observatory 1.0-m f/7.7 reflector show a coma diameter of 7" with a diffuse edge in p.a. 60 degrees; magnitudes of 18.3-19.1 were measured in an 11" aperture. Sixteen stacked 15-s exposures taken by K. Yoshimoto (Kumage, Yamaguchi, Japan) with a 0.51-m f/6.8 reflector located at Siding Spring, NSW, Australia, on Nov. 6.49 show a diffuse coma 15" in diameter of total magnitude 17.8 with no tail. Thirty stacked 8-s exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) with a 0.51-m f/6.8 astrograph located at Siding Spring on Nov. 6.53-6.58 show a strongly condensed coma 12" in diameter with no tail; the magnitude was 17.9 as measured within a circular aperture of radius 6".5. Three-hundred-forty-two stacked 8-s exposures taken on Nov. 7.7 by A. Aletti (and measured by M. Auteri and Aletti) with a 0.36-m f/7.5 reflector at Varese, Italy, show this object to be clearly a comet with a slightly condensed 8" coma of mag 18.2 and a faint, straight tail at least 15" long in p.a. 75 degrees. One- hundred stacked 13-s exposures taken by L. Buzzi and G. Galli with a 0.84-m f/3.5 reflector at Varese (measured by Buzzi, Galli, and Aletti) on Nov. 7.8 show a moderately diffuse 8" coma with a tail 15" long in p.a. 75 degrees. R. Bouma, Groningen, The Netherlands, notes that this comet's orbital elements appear similar to that of the C/1988 A1 group of comets that also includes C/1996 Q1, C/2015 F3, and C/2019 Y1. The available astrometry appears on MPEC 2023-V193. The following preliminary parabolic orbital elements by S. Nakano (Central Bureau) are from 114 observations spanning Nov. 6-10 (mean residual 0".7); these elements indicate that the comet passed 0.22 AU from the earth on 2023 Nov. 4 UT. T = 2023 Dec. 14.08199 TT Peri. = 57.23504 Node = 31.55731 2000.0 q = 0.8447278 AU Incl. = 73.39038 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 21.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2023 10 23 02 44.99 -35 47.6 0.358 1.260 131.2 36.5 19.6 2023 10 28 01 29.71 -32 55.6 0.274 1.199 133.4 37.1 18.8 2023 11 02 23 43.95 -22 38.6 0.227 1.139 125.6 45.1 18.2 2023 11 07 22 02.72 -05 56.0 0.237 1.083 106.6 61.3 18.2 2023 11 12 20 53.49 +07 29.4 0.298 1.030 89.2 74.0 18.5 2023 11 17 20 10.27 +15 26.4 0.384 0.982 77.7 79.8 18.9 2023 11 22 19 41.96 +20 05.2 0.479 0.939 70.0 81.4 19.2 2023 11 27 19 21.86 +22 56.6 0.578 0.903 64.4 80.4 19.5 2023 12 02 19 06.50 +24 45.2 0.675 0.874 60.1 77.9 19.7 2023 12 07 18 54.06 +25 53.1 0.769 0.855 56.7 74.5 19.9 2023 12 12 18 43.58 +26 32.5 0.858 0.846 54.1 70.6 20.1 2023 12 17 18 34.52 +26 50.9 0.940 0.846 52.1 66.6 20.3 2023 12 22 18 26.57 +26 53.7 1.014 0.858 50.8 62.7 20.5 2023 12 27 18 19.55 +26 45.3 1.080 0.878 50.1 59.2 20.7 2024 01 01 18 13.30 +26 29.6 1.137 0.908 50.1 56.1 20.9 2024 01 06 18 07.69 +26 09.8 1.185 0.945 50.7 53.6 21.2 2024 01 11 18 02.54 +25 48.7 1.223 0.989 51.9 51.5 21.4 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2023 CBAT 2023 November 11 (CBET 5316) Daniel W. E. Green