Electronic Telegram No. 5400 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 P/2024 H1 = P/2018 L5 (Leonard) Erwin Schwab, Egelsbach, Germany, reports his recovery of comet P/2018 L5 (cf. CBET 4528) on CCD images that he obtained (along with F. Ocana, L. Conversi, R. Kresken, and M. Micheli) using the 0.8-m f/3 Schmidt telescope at Calar Alto on Apr. 18, when twelve stacked 60-s exposures showed no tail and no coma visible. Schwab obtained eight 60-s confirming frames with a 1.0-m f/8 reflector of Las Cumbres Observatory at Sutherland, South Africa, on Apr. 21; when he stacked the eight exposures, they show no tail, but the head shows a size of 2".3 (full-width-at-half-maximum) compared to nearby stars with FWHM 1".5. Schwab's astrometry is given below. 2024 UT R.A. (2000) Decl. Mag. Observer Apr. 18.06708 15 03 32.70 -17 07 04.8 20.7 Schwab 18.07627 15 03 32.31 -17 07 03.2 21.1 " 18.08546 15 03 31.96 -17 07 01.2 21.1 " 18.09465 15 03 31.64 -17 06 59.4 20.6 " 21.11250 15 01 35.65 -16 56 58.8 21.2 " 21.12090 15 01 35.29 -16 56 57.4 20.8 " 21.12928 15 01 34.93 -16 56 55.6 21.3 " Additional astrometry appears on MPEC 2024-K145, which includes observations made at two observatories in incidental astrometry sent to the Minor Planet Center (and identified with this comet at the MPC): images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on May 3, 9, and 29; and images obtained with the 1.5-m Mt. Lemmon Survey reflector on Apr. 29 (with the magnitudes given as 19.9-21.0) and May 9 (mag 20.0-21.1). The residuals for the recovery observations are +48" in R.A. and -12" in Decl. from the prediction in NK 4854 and the ICQ's Comet Handbook 2024, with a corresponding correction of Delta(T) = -0.054 day. The following linked orbital elements by S. Nakano (Central Bureau) are from 219 observations spanning 2018 June 8-2024 May 29 (mean residual 0".5). The comet passed 0.40 and 0.37 AU from Jupiter on 1978 July 19 and 2014 Sept. 25 UT, respectively. A search by Nakano of archival astrometry produced no definite observations of this comet, but there is a possible identification with 1937 BG (a single observation) with residuals of +0.39 deg in R.A. and -0.01 deg in Decl., with a corresponding correction of Delta(T) = +3.7 days. Epoch = 2001 July 30.0 TT T = 2001 July 14.89821 TT Peri. = 18.35548 e = 0.1747547 Node = 294.15866 2000.0 q = 3.5102781 AU Incl. = 3.48230 a = 4.2536180 AU n = 0.11234826 P = 8.77 years Epoch = 2010 Mar. 25.0 TT T = 2010 Apr. 9.85065 TT Peri. = 17.94233 e = 0.1773608 Node = 294.14368 2000.0 q = 3.4964970 AU Incl. = 3.48227 a = 4.2503412 AU n = 0.11247821 P = 8.76 years Epoch = 2018 May 2.0 TT T = 2018 May 4.47949 TT Peri. = 93.63886 e = 0.3644086 Node = 219.15712 2000.0 q = 2.3033244 AU Incl. = 2.20919 a = 3.6239073 AU n = 0.14286915 P = 6.90 years Epoch = 2025 Mar. 26.0 TT T = 2025 Apr. 3.84050 TT Peri. = 93.94579 e = 0.3635962 Node = 219.02484 2000.0 q = 2.3089275 AU Incl. = 2.20948 a = 3.6280859 AU n = 0.14262240 P = 6.91 years Epoch = 2032 Feb. 18.0 TT T = 2032 Feb. 27.27324 TT Peri. = 93.55033 e = 0.3616592 Node = 218.91580 2000.0 q = 2.3202551 AU Incl. = 2.20771 a = 3.6348221 AU n = 0.14222611 P = 6.93 years Epoch = 2039 Feb. 21.0 TT T = 2039 Feb. 3.41582 TT Peri. = 93.70213 e = 0.3597946 Node = 218.76232 2000.0 q = 2.3316880 AU Incl. = 2.20612 a = 3.6420935 AU n = 0.14180040 P = 6.95 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 13.5 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 05 10 14 47.60 -15 44.1 2.083 3.090 174.7 1.7 20.0 2024 05 20 14 40.05 -15 03.3 2.073 3.055 163.1 5.5 19.9 2024 05 30 14 33.43 -14 26.2 2.088 3.020 151.8 9.1 19.9 2024 06 09 14 28.37 -13 56.5 2.127 2.985 140.9 12.4 19.9 2024 06 19 14 25.33 -13 36.8 2.187 2.950 130.6 15.2 19.9 2024 06 29 14 24.52 -13 28.8 2.261 2.916 120.8 17.4 19.9 2024 07 09 14 25.99 -13 32.5 2.347 2.881 111.6 19.1 19.9 2024 07 19 14 29.68 -13 47.6 2.441 2.848 103.0 20.3 20.0 2024 07 29 14 35.44 -14 12.6 2.538 2.814 94.9 21.1 20.0 2024 08 08 14 43.12 -14 46.1 2.638 2.781 87.3 21.4 20.0 2024 08 18 14 52.56 -15 26.4 2.735 2.748 80.1 21.3 20.1 2024 08 28 15 03.59 -16 11.6 2.830 2.716 73.2 20.9 20.1 2024 09 07 15 16.08 -17 00.0 2.920 2.685 66.6 20.2 20.1 2024 09 17 15 29.91 -17 49.8 3.005 2.654 60.3 19.2 20.1 2024 09 27 15 44.97 -18 39.2 3.082 2.624 54.2 18.0 20.1 2024 10 07 16 01.18 -19 26.8 3.151 2.595 48.3 16.7 20.1 2024 10 17 16 18.42 -20 10.7 3.212 2.567 42.5 15.2 20.1 2025 03 26 21 50.44 -11 15.9 2.993 2.310 39.3 15.9 19.5 2025 04 05 22 09.42 -09 30.7 2.918 2.309 44.2 17.6 19.5 2025 04 15 22 27.76 -07 43.4 2.838 2.310 49.1 19.2 19.4 2025 04 25 22 45.44 -05 55.4 2.754 2.313 54.2 20.6 19.3 2025 05 05 23 02.38 -04 08.2 2.666 2.319 59.3 22.0 19.3 2025 05 15 23 18.53 -02 23.5 2.574 2.326 64.6 23.1 19.2 2025 05 25 23 33.80 -00 42.7 2.479 2.335 70.0 24.1 19.2 2025 06 04 23 48.08 +00 52.7 2.381 2.346 75.7 24.8 19.1 2025 06 14 00 01.24 +02 21.1 2.282 2.359 81.6 25.2 19.0 2025 06 24 00 13.10 +03 41.0 2.182 2.374 87.9 25.3 18.9 2025 07 04 00 23.46 +04 50.8 2.082 2.390 94.6 25.1 18.9 2025 07 14 00 32.09 +05 48.8 1.985 2.408 101.8 24.4 18.8 2025 07 24 00 38.73 +06 33.5 1.891 2.428 109.5 23.2 18.7 2025 08 03 00 43.12 +07 03.0 1.804 2.449 117.9 21.5 18.7 2025 08 13 00 45.07 +07 16.2 1.726 2.471 126.9 19.1 18.6 2025 08 23 00 44.48 +07 11.9 1.661 2.495 136.7 16.1 18.6 2025 09 02 00 41.46 +06 50.4 1.612 2.520 147.2 12.5 18.6 2025 09 12 00 36.39 +06 13.5 1.584 2.546 158.2 8.4 18.6 2025 09 22 00 29.92 +05 25.1 1.580 2.574 169.7 4.0 18.6 2025 10 02 00 22.96 +04 31.0 1.601 2.602 177.5 1.0 18.7 2025 10 12 00 16.47 +03 38.0 1.650 2.631 166.5 5.1 18.8 2025 10 22 00 11.28 +02 52.1 1.725 2.661 155.2 9.0 18.9 2025 11 01 00 07.99 +02 18.3 1.823 2.692 144.3 12.4 19.1 2025 11 11 00 06.91 +01 59.1 1.942 2.723 133.9 15.2 19.3 2025 11 21 00 08.05 +01 55.2 2.078 2.755 124.0 17.3 19.5 2025 12 01 00 11.33 +02 06.2 2.228 2.788 114.7 18.7 19.7 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 May 31 (CBET 5400) Daniel W. E. Green