Electronic Telegram No. 5377 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 E2 (BOK) An apparently asteroidal object with a nearly parabolic orbit that was discovered on CCD images obtained by M. J. Brucker on Mar. 10 and 11 with the 2.25 "Bok" reflector at Kitt Peak as part of the Catalina Sky Survey (cf. CBET 5103) has been found to show cometary appearance on images taken elsewhere after it was posted on the Minor Planet Center's PCCP webpage. The discovery observations are tabulated below. 2024 UT R.A. (2000) Decl. Mag. Observer Mar. 10.25252 8 29 30.82 +22 09 00.7 22.7 Brucker 10.25814 8 29 30.59 +22 09 01.6 22.3 " 10.26376 8 29 30.34 +22 09 02.9 22.3 " 10.26937 8 29 30.14 +22 09 04.0 23.5 " 11.19206 8 28 53.95 +22 12 26.2 21.8 " 11.20024 8 28 53.62 +22 12 27.6 22.0 " 11.20465 8 28 53.44 +22 12 28.8 22.0 " 11.20836 8 28 53.30 +22 12 29.5 21.8 " J. Maikner (New Ringgold, PA, USA) reports that fifty 120-s CCD exposures taken on Mar. 14.09 UT with a 0.30-m f/3.8 Riccardi-Honders telescope show a condensed coma of size 2" with a straight tail 9".5 long in p.a. 130 degrees. Further reports of cometary activity and astrometry appear on MPEC 2024-F91. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 44 observations spanning Mar. 10-25 (mean residual 0".3). There is no close approach to any major planet. T = 2023 July 24.33710 TT Peri. = 351.93192 Node = 135.74926 2000.0 q = 7.671572 AU Incl. = 156.12627 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 9.5 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 02 20 08 43.67 +20 48.4 6.862 7.782 157.2 2.8 20.8 2024 03 01 08 35.98 +21 32.7 6.958 7.793 145.2 4.2 20.8 2024 03 11 08 29.02 +22 11.7 7.087 7.804 133.5 5.3 20.9 2024 03 21 08 23.00 +22 45.3 7.241 7.815 122.1 6.2 20.9 2024 03 31 08 18.01 +23 13.6 7.414 7.827 111.0 6.8 21.0 2024 04 10 08 14.10 +23 37.0 7.601 7.840 100.2 7.2 21.1 2024 04 20 08 11.27 +23 56.0 7.794 7.853 89.7 7.3 21.1 2024 04 30 08 09.46 +24 11.3 7.987 7.866 79.5 7.2 21.2 2024 05 10 08 08.59 +24 23.4 8.175 7.880 69.6 6.9 21.2 2024 09 27 08 34.28 +26 10.2 8.575 8.120 60.0 6.1 21.4 2024 10 07 08 34.49 +26 31.7 8.432 8.140 69.8 6.6 21.4 2024 10 17 08 33.87 +26 57.4 8.278 8.161 79.8 6.9 21.4 2024 10 27 08 32.34 +27 27.5 8.119 8.182 90.1 7.0 21.4 2024 11 06 08 29.79 +28 01.9 7.961 8.203 100.7 6.8 21.3 2024 11 16 08 26.14 +28 40.1 7.811 8.225 111.5 6.4 21.3 2024 11 26 08 21.37 +29 21.5 7.674 8.248 122.6 5.8 21.3 2024 12 06 08 15.48 +30 04.9 7.557 8.270 133.8 4.9 21.2 2024 12 16 08 08.55 +30 48.9 7.467 8.293 145.1 3.9 21.2 2024 12 26 08 00.75 +31 31.9 7.408 8.316 156.1 2.8 21.2 2025 01 05 07 52.30 +32 12.0 7.384 8.340 165.5 1.7 21.2 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 March 28 (CBET 5377) Daniel W. E. Green