Electronic Telegram No. 5289 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 13P/OLBERS A. Hale, Cloudcroft, NM, USA, reports his recovery of this comet, which was last seen in 1956 (cf. IAUCs 1536, 1561), with Hale's astrometry tabulated below. The comet appears basically stellar. All CCD images were obtained remotely with Las Cumbres Observatory 1.0-m f/8 Schmidt-Cassegrain telescopes: those on Aug. 13, 25, 27, and 28 UT were obtained with reflectors at the South African Astronomical Observatory, Sutherland; those on Aug. 24 and 26 were obtained at Siding Spring Observatory (NSW, Australia). 2023 UT R.A. (2000) Decl. Mag. Observer Aug. 13.06550 4 14 17.42 -14 17 56.3 21.6 Hale 13.07279 4 14 17.74 -14 17 58.1 " 24.68270 4 20 27.83 -14 55 56.0 22.0 " 24.69000 4 20 28.05 -14 55 57.7 21.8 " 25.11247 4 20 39.85 -14 57 34.7 21.8 " 25.11812 4 20 39.95 -14 57 36.2 23.2 " 25.14712 4 20 40.78 -14 57 42.7 21.6 " 25.15441 4 20 40.96 -14 57 44.8 21.8 " 26.66125 4 21 22.11 -15 03 36.2 21.0 " 26.66853 4 21 22.36 -15 03 38.3 21.8 " 27.01746 4 21 31.57 -15 05 01.5 21.1 " 27.02476 4 21 31.73 -15 05 03.2 21.2 " 27.11624 4 21 34.13 -15 05 25.9 22.1 " 27.12355 4 21 34.34 -15 05 27.5 22.0 " 28.15906 4 22 01.23 -15 09 39.4 21.1 " 28.16636 4 22 01.43 -15 09 41.1 21.3 " The residuals for the recovery observations were +150" in R.A. and +145" in Decl. from the prediction in NK 3997 (and ICQ Comet Handbooks 2020-2023), with a corresponding correction of Delta(T) = -0.50 day. The following linked orbital elements by S. Nakano (Central Bureau) are from 86 observations spanning 1887-2023 (weighted mean residual 1".5), and non-gravitational parameters A1 = +1.07 +/- 0.10, A2 = +0.0589 +/- 0.0001. The comet passed 0.081 AU from Mars on 1887 July 28, 1.52 AU from Jupiter on 1889 Jan. 11, and 4.41 AU from Saturn on 1959 Mar. 22 UT. The 1815 observations are no longer fitting and yield residuals of about 0.4 deg from this orbit. The reduction of observations in 1815-1888 were made by T. Kobayashi and used by Nakano. Epoch = 1887 Oct. 16.0 TT T = 1887 Oct. 8.97348 TT Peri. = 65.35576 e = 0.9309542 Node = 86.05833 2000.0 q = 1.1990949 AU Incl. = 44.56950 a = 17.3666626 AU n = 0.01361851 P = 72.37 years Epoch = 1956 June 16.0 TT T = 1956 June 19.13771 TT Peri. = 64.64231 e = 0.9303124 Node = 86.10516 2000.0 q = 1.1784698 AU Incl. = 44.60846 a = 16.9107455 AU n = 0.01417294 P = 69.54 years Epoch = 2024 June 19.0 TT T = 2024 June 30.02023 TT Peri. = 64.41161 e = 0.9302910 Node = 85.84836 2000.0 q = 1.1754968 AU Incl. = 44.66460 a = 16.8629037 AU n = 0.01423330 P = 69.25 years Epoch = 2094 Mar. 24.0 TT T = 2094 Mar. 20.45699 TT Peri. = 64.48838 e = 0.9308090 Node = 85.65568 2000.0 q = 1.1832283 AU Incl. = 44.57579 a = 17.1009066 AU n = 0.01393719 P = 70.72 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 4.5 and 2.5n = 20 for pre-perihelion and H = 5.5 and 2.5n = 10 for post-perihelion (based photographic and visual magnitudes made at the 1956 return). Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2023 08 04 04 08.60 -13 57.1 4.308 4.199 77.1 13.6 20.1 2023 08 14 04 14.83 -14 20.6 4.093 4.106 83.6 14.2 19.8 2023 08 24 04 20.14 -14 53.4 3.877 4.013 90.4 14.6 19.5 2023 09 03 04 24.30 -15 35.0 3.661 3.918 97.3 14.8 19.2 2023 09 13 04 27.06 -16 24.7 3.448 3.823 104.3 14.8 18.8 2023 09 23 04 28.15 -17 20.7 3.242 3.727 111.4 14.5 18.5 2023 10 03 04 27.30 -18 20.5 3.045 3.630 118.5 14.0 18.1 2023 10 13 04 24.24 -19 20.4 2.861 3.533 125.3 13.3 17.7 2023 10 23 04 18.79 -20 15.1 2.694 3.434 131.4 12.6 17.4 2023 11 02 04 10.92 -20 57.9 2.547 3.335 136.2 11.9 17.0 2023 11 12 04 00.84 -21 21.1 2.422 3.235 138.9 11.6 16.6 2023 11 22 03 49.05 -21 17.0 2.322 3.134 138.8 12.0 16.3 2023 12 02 03 36.41 -20 39.7 2.248 3.032 135.5 13.2 15.9 2023 12 12 03 23.89 -19 26.2 2.199 2.929 129.8 15.0 15.5 2023 12 22 03 12.57 -17 37.5 2.173 2.825 122.4 17.1 15.2 2024 01 01 03 03.28 -15 17.9 2.167 2.721 114.1 19.3 14.9 2024 01 11 02 56.57 -12 33.7 2.176 2.616 105.5 21.2 14.5 2024 01 21 02 52.72 -09 31.1 2.197 2.511 96.8 22.9 14.2 2024 01 31 02 51.75 -06 16.0 2.223 2.405 88.3 24.2 13.9 2024 02 10 02 53.57 -02 52.5 2.251 2.299 80.2 25.0 13.5 2024 02 20 02 58.02 +00 36.4 2.278 2.193 72.4 25.5 13.1 2024 03 01 03 04.93 +04 09.0 2.300 2.087 65.1 25.5 12.7 2024 03 11 03 14.18 +07 44.3 2.316 1.981 58.2 25.2 12.3 2024 03 21 03 25.72 +11 22.1 2.322 1.877 51.8 24.6 11.8 2024 03 31 03 39.54 +15 02.0 2.319 1.774 45.9 23.8 11.3 2024 04 10 03 55.78 +18 43.8 2.305 1.675 40.5 22.9 10.8 2024 04 20 04 14.64 +22 27.1 2.281 1.578 35.7 21.8 10.3 2024 04 30 04 36.46 +26 10.3 2.247 1.488 31.7 20.9 9.7 2024 05 10 05 01.77 +29 50.9 2.204 1.404 28.6 20.2 9.2 2024 05 20 05 31.22 +33 23.9 2.154 1.329 26.6 19.9 8.6 2024 05 30 06 05.58 +36 41.0 2.099 1.267 25.9 20.4 8.2 2024 06 09 06 45.62 +39 29.1 2.043 1.218 26.3 21.7 7.8 2024 06 19 07 31.66 +41 30.4 1.989 1.188 27.7 23.5 7.5 2024 06 29 08 22.99 +42 23.4 1.942 1.176 29.9 25.5 7.3 2024 07 09 09 17.51 +41 49.5 1.909 1.183 32.4 27.4 7.6 2024 07 19 10 11.91 +39 41.1 1.895 1.211 34.9 28.7 7.7 2024 07 29 11 03.06 +36 07.1 1.906 1.255 37.1 29.2 7.9 2024 08 08 11 49.13 +31 29.9 1.943 1.315 38.7 28.8 8.1 2024 08 18 12 29.69 +26 17.8 2.008 1.388 39.6 27.7 8.4 2024 08 28 13 05.23 +20 56.5 2.098 1.470 39.7 26.0 8.8 2024 09 07 13 36.61 +15 44.9 2.210 1.559 38.8 23.9 9.2 2024 09 17 14 04.67 +10 54.9 2.340 1.654 37.2 21.5 9.5 2024 09 27 14 30.11 +06 32.0 2.482 1.754 34.7 19.0 9.9 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2023 CBAT 2023 August 28 (CBET 5289) Daniel W. E. Green