Electronic Telegram No. 5364 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 E1 (WIERZCHOS) Kacper W. Wierzchos, University of Arizona, reports his discovery of a comet on four 30-s CCD images obtained on Mar. 3 UT with the Mt. Lemmon Survey 1.5-m reflector (discovery observations tabulated below). The object showed a 4" coma with a slight elongation in p.a. 320 degrees, indicating the presence of a possible 6" tail. Wierzchos also obtained three 60-s follow-up unfiltered images for confirmation of cometary appearance. 2024 UT R.A. (2000) Decl. Mag. Observer Mar. 3.44584 17 19 12.26 +55 07 02.0 20.4 Wierzchos 3.45111 17 19 12.41 +55 07 04.6 20.1 " 3.45637 17 19 12.45 +55 07 05.8 21.0 " 3.46161 17 19 12.52 +55 07 07.8 20.8 " 3.46783 17 19 12.59 +55 07 10.7 20.3 " 3.47182 17 19 12.66 +55 07 12.2 20.9 " 3.47589 17 19 12.73 +55 07 13.4 20.3 " After the comet was posted on the Minor Planet Center's PCCP webpage, W. Ryan obtained images in poor seeing on Mar. 4.5 UT with the Magdalena Ridge Observatory 2.4-m reflector that show a definitive fuzzy appearance (very condensed coma of size 4".5) with respect to field stars (comet's full-width- at-half-maximum size was consistently 30 percent greater than nearby stars in both single and stacked images) with a possible short elongation at p.a. about 295 degrees. The astrometry appears on MPEC 2024-E102 and includes pre-discovery observations made on Feb. 15.5 (at mag R = 20.4 and g = 21.4) and 29.4-29.5 UT (mag R = 20.7, g = 20.5) with the 1.2-m Schmidt telescope at Palomar that were reported later to the Minor Planet Center. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 27 observations spanning 2024 Feb. 15-Mar. 6 (mean residual 0".2). T = 2026 Jan. 21.38303 TT Peri. = 243.67215 Node = 108.44951 2000.0 q = 0.5622944 AU Incl. = 75.21409 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 8.5, and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 02 20 17 15.35 +53 51.7 8.105 8.161 89.8 7.0 20.3 2024 03 01 17 18.60 +54 51.7 7.985 8.079 91.9 7.0 20.3 2024 03 11 17 20.58 +55 55.7 7.869 7.996 93.8 7.1 20.2 2024 03 21 17 21.12 +57 01.8 7.757 7.913 95.4 7.2 20.1 2024 03 31 17 20.05 +58 07.7 7.651 7.829 96.6 7.3 20.1 2024 04 10 17 17.24 +59 11.0 7.550 7.745 97.5 7.4 20.0 2024 04 20 17 12.61 +60 08.9 7.456 7.661 98.0 7.5 19.9 2024 04 30 17 06.20 +60 58.6 7.368 7.576 98.1 7.6 19.9 2024 05 10 16 58.16 +61 37.3 7.286 7.491 97.8 7.7 19.8 2024 05 20 16 48.79 +62 02.5 7.211 7.405 97.1 7.8 19.7 2024 05 30 16 38.56 +62 12.3 7.143 7.319 96.0 7.9 19.7 2024 06 09 16 28.04 +62 05.5 7.080 7.232 94.6 8.0 19.6 2024 06 19 16 17.84 +61 41.8 7.022 7.145 92.9 8.2 19.6 2024 06 29 16 08.52 +61 02.1 6.968 7.057 90.9 8.3 19.5 2024 07 09 16 00.54 +60 07.8 6.918 6.969 88.7 8.4 19.4 2024 07 19 15 54.20 +59 00.8 6.871 6.881 86.3 8.5 19.4 2024 07 29 15 49.66 +57 43.8 6.825 6.791 83.8 8.5 19.3 2024 08 08 15 46.94 +56 18.9 6.780 6.702 81.3 8.6 19.3 2024 08 18 15 45.99 +54 48.9 6.734 6.612 78.7 8.6 19.2 2024 08 28 15 46.70 +53 15.8 6.687 6.521 76.2 8.7 19.1 2024 09 07 15 48.93 +51 41.8 6.637 6.429 73.8 8.7 19.1 2024 09 17 15 52.53 +50 08.9 6.584 6.337 71.5 8.7 19.0 2024 09 27 15 57.35 +48 38.6 6.527 6.245 69.4 8.6 18.9 2024 10 07 16 03.23 +47 12.6 6.464 6.152 67.5 8.6 18.9 2024 10 17 16 10.06 +45 52.2 6.395 6.058 66.0 8.6 18.8 2024 10 27 16 17.68 +44 38.8 6.320 5.963 64.7 8.7 18.7 2024 11 06 16 26.00 +43 33.3 6.237 5.868 63.8 8.7 18.6 2024 11 16 16 34.88 +42 37.0 6.147 5.772 63.4 8.8 18.5 2024 11 26 16 44.22 +41 50.7 6.050 5.676 63.3 8.9 18.4 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 March 7 (CBET 5364) Daniel W. E. Green