Electronic Telegram No. 5475 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/2024 V2 (SARNECZKY) Krisztian Sarneczky [in TeX form: Kriszti\'an S\'arneczky], Konkoly Observatory, reports the discovery of a comet in twelve 60-s stacked w-band CCD images (limiting mag about 21) taken on Nov. 10.1 UT at the Piszkesteto Observatory in Hungary with the 0.60-m Schmidt telescope (discovery observations tabulated below). Fifteen 50-s stacked follow-up images taken one hour after the discovery show a condensed coma 7" in diameter and a faint, 12"-long straight tail in p.a. 280 deg. Fifteen 60-s stacked follow-up images taken on next night (Nov. 11.1) with the same telescope show a condensed but elongated coma of size 8" x 12" with an ill-defined optocenter. The straight, but slightly widening, tail was 25" long in p.a. 280 deg. The morphological changes between the two nights suggest, that the object is in a possible disintegration event, but more observations are encouraged. Twenty-two stacked 60-s CCD exposures taken by the discoverer with the 0.60-m Schmidt telescope Nov. 12.07 show a diffuse coma 12" in diameter with a 30"-long straight tail toward p.a. 280 deg; the G magnitude was 19.6 as measured within a circular aperture of radius 6". 2024 UT R.A. (2000) Decl. Mag. Observer Nov. 10.09731 11 03 48.71 +31 48 27.1 19.8 Sarneczky 10.10845 11 03 52.08 +31 49 14.0 19.7 " 10.11959 11 03 55.37 +31 50 01.7 19.8 " 10.14845 11 04 03.86 +31 52 04.2 " 10.15428 11 04 05.58 +31 52 29.6 19.5 " After the comet was posted on the Minor Planet Center's PCCP webpage, other astrometrists also commented on the cometary appearance. Twenty-four stacked 20-s CCD exposures taken remotely on Nov. 10.5 UT by H. Sato (Bunkyo-ku, Tokyo, Japan) using a 0.51-m f/6.8 astrograph located at the Utah Desert Remote Observatory near Beryl Junction, UT, USA, show a strongly condensed coma 6" in diameter with no tail; the magnitude was 19.4 as measured within a circular aperture of radius 4".9. Seventy-nine stacked CMO images obtained on Nov. 11.2 UT by L. Buzzi at Varese, Italy, with a 0.84-m f/3.5 reflector (measured by A. Aletti and Buzzi) show a moderately diffuse 6" coma and a 12"-long fan-shaped tail in p.a. about 280 degrees. The available astrometry appears on MPEC 2024-W9. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 43 observations spanning Nov. 10-17 (mean residual 0".8). T = 2024 Nov. 4.34442 TT Peri. = 14.27514 Node = 102.46071 2000.0 q = 1.2471946 AU Incl. = 96.08550 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 18.5 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 10 17 09 44.09 +10 08.5 1.465 1.279 59.0 41.9 20.2 2024 10 22 09 56.31 +13 34.1 1.371 1.264 62.2 44.2 20.0 2024 10 27 10 10.18 +17 30.2 1.279 1.254 65.6 46.2 19.8 2024 11 01 10 26.24 +22 01.0 1.193 1.248 69.0 47.9 19.7 2024 11 06 10 45.26 +27 09.1 1.115 1.247 72.4 49.2 19.5 2024 11 11 11 08.33 +32 52.8 1.049 1.251 75.6 50.0 19.4 2024 11 16 11 36.91 +39 02.5 0.999 1.260 78.7 50.3 19.3 2024 11 21 12 12.89 +45 16.8 0.968 1.273 81.2 50.1 19.3 2024 11 26 12 58.12 +51 01.6 0.959 1.291 83.1 49.4 19.3 2024 12 01 13 53.19 +55 35.7 0.972 1.312 84.2 48.4 19.4 2024 12 06 14 55.25 +58 25.9 1.007 1.338 84.4 47.1 19.5 2024 12 11 15 57.59 +59 25.0 1.060 1.367 83.8 45.7 19.7 2024 12 16 16 53.30 +58 55.7 1.128 1.400 82.7 44.2 19.9 2024 12 21 17 39.23 +57 33.5 1.208 1.435 81.1 42.6 20.2 2024 12 26 18 15.75 +55 48.7 1.296 1.473 79.2 41.0 20.4 2024 12 31 18 44.66 +54 00.7 1.390 1.513 77.1 39.3 20.7 2025 01 05 19 07.84 +52 19.5 1.487 1.556 75.0 37.6 20.9 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 November 18 (CBET 5475) Daniel W. E. Green