Electronic Telegram No. 5716 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 (875163) = COMET P/1998 SH_2 = P/2016 EC_156 MPEC 2026-N79 reports the discovery of cometary activity in this Apollo- type minor planet. It was originally discovered on 1998 Sept. 17 with the 0.9-m Spacewatch telescope at Kitt Peak (discovery astrometry tabulated below), when it was given the minor-planet designation 1998 SH_2 (cf. MPEC 1998-S10). 1998 UT R.A. (2000) Decl. Mag. Sept.17.44420 1 06 22.71 + 3 05 15.8 19.1 17.46535 1 06 17.16 + 3 05 06.6 19.2 17.49046 1 06 10.67 + 3 04 55.5 19.2 18.31880 1 02 52.36 + 2 59 03.7 19.3 18.32284 1 02 51.37 + 2 59 01.9 19.2 18.32688 1 02 50.36 + 2 59 00.2 19.3 It was re-discovered on 2016 Mar. 10.2 UT at mag 21 on CCD images obtained with the Mt. Lemmon Survey 1.5-m reflector, whence it was given the minor- planet designation 2016 EC_156 (cf. MPEC 2016-E164). R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the following previously unpublished astrometry for (875163) obtained with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea by R. Wainscoat and himself: 2025 UT R.A. (2000) Decl. Mag. Sept.17.43982 23 39 24.21 - 5 44 14.0 17.7 17.44186 23 39 24.08 - 5 44 11.6 17.6 17.44375 23 39 23.96 - 5 44 09.3 17.6 18.46708 23 38 40.49 - 5 25 02.0 17.8 18.46967 23 38 40.34 - 5 24 59.2 17.8 18.47226 23 38 40.22 - 5 24 57.1 17.6 18.47485 23 38 40.05 - 5 24 53.7 17.8 18.47744 23 38 39.90 - 5 24 50.9 17.7 18.48035 23 38 39.73 - 5 24 47.8 17.7 18.48294 23 38 39.60 - 5 24 45.2 17.7 18.48553 23 38 39.44 - 5 24 42.3 17.7 18.48812 23 38 39.30 - 5 24 39.5 17.7 18.49073 23 38 39.15 - 5 24 36.6 17.7 18.49332 23 38 39.01 - 5 24 34.0 17.7 23.48759 23 36 09.44 - 4 14 13.2 18.5 23.49018 23 36 09.36 - 4 14 11.4 18.4 23.49277 23 36 09.27 - 4 14 09.6 18.5 23.49536 23 36 09.18 - 4 14 07.8 18.5 23.49796 23 36 09.10 - 4 14 06.0 18.5 23.50056 23 36 09.01 - 4 14 04.3 18.5 30.38428 23 34 39.97 - 3 11 44.0 19.4 30.38688 23 34 39.93 - 3 11 42.9 19.3 30.38947 23 34 39.89 - 3 11 41.6 19.6 30.39205 23 34 39.84 - 3 11 40.6 19.3 30.39464 23 34 39.80 - 3 11 39.4 19.3 30.39723 23 34 39.76 - 3 11 38.3 19.3 Three 120-s gri-band images obtained in 0".7 seeing on 2025 Sept. 17.4 UT and eleven 180-s gri-band images obtained in 1".0 seeing on 2025 Sept. 18.5 (queue observer L. Wells; queue coordinator H. Flewelling) show a head of similar size to nearby stars but with a straight tail about 20" long toward p.a. 265 degrees. No name will be assigned to this comet, as minor-planet names cannot be duplicated. The following new orbital elements by S. Nakano (Central Bureau) are from 397 observations spanning 1998-2025 (mean residual 0".4). There are no detectable non-gravitational forces, contrary to the claim by Farnocchia et al. (2026, *Nature Astron.*; via https://doi.org/10.1038/s41550-026-02913-7). The comet passed 0.0208 AU from the earth on 2025 Aug. 30 and will pass 0.0695 AU from the earth on 2052 Sept. 8 UT; also, the comet will pass 0.98 AU from Jupiter on 2037 July 4. Epoch = 1998 July 6.0 TT T = 1998 July 18.27083 TT Peri. = 259.92935 e = 0.7210182 Node = 14.29747 2000.0 q = 0.7596089 AU Incl. = 2.48760 a = 2.7227906 AU n = 0.21937276 P = 4.49 years Epoch = 2003 Jan. 1.0 TT T = 2003 Jan. 8.34953 TT Peri. = 261.12311 e = 0.7251913 Node = 13.17115 2000.0 q = 0.7443006 AU Incl. = 2.49041 a = 2.7084319 AU n = 0.22111957 P = 4.46 years Epoch = 2007 June 29.0 TT T = 2007 June 23.49655 TT Peri. = 261.20139 e = 0.7257667 Node = 13.08243 2000.0 q = 0.7424485 AU Incl. = 2.49020 a = 2.7073603 AU n = 0.22125088 P = 4.46 years Epoch = 2011 Dec. 25.0 TT T = 2011 Dec. 7.56551 TT Peri. = 261.24037 e = 0.7248807 Node = 13.04625 2000.0 q = 0.7453820 AU Incl. = 2.48884 a = 2.7093045 AU n = 0.22101275 P = 4.46 years Epoch = 2016 June 21.0 TT T = 2016 June 19.70320 TT Peri. = 268.30338 e = 0.7136506 Node = 6.48824 2000.0 q = 0.7859407 AU Incl. = 2.40381 a = 2.7446911 AU n = 0.21675238 P = 4.55 years Epoch = 2020 Dec. 17.0 TT T = 2021 Jan. 5.50116 TT Peri. = 268.46101 e = 0.7142148 Node = 6.36322 2000.0 q = 0.7837726 AU Incl. = 2.40391 a = 2.7425233 AU n = 0.21700942 P = 4.54 years Epoch = 2025 July 24.0 TT T = 2025 July 21.38931 TT Peri. = 268.42955 e = 0.7139100 Node = 6.36751 2000.0 q = 0.7848738 AU Incl. = 2.40426 a = 2.7434508 AU n = 0.21689937 P = 4.54 years Epoch = 2030 Jan. 19.0 TT T = 2030 Feb. 3.61053 TT Peri. = 268.68646 e = 0.7138098 Node = 6.06275 2000.0 q = 0.7851458 AU Incl. = 2.42542 a = 2.7434401 AU n = 0.21690065 P = 4.54 years Epoch = 2034 Aug. 26.0 TT T = 2034 Aug. 23.47806 TT Peri. = 268.93969 e = 0.7136316 Node = 5.86400 2000.0 q = 0.7860227 AU Incl. = 2.42408 a = 2.7447955 AU n = 0.21674001 P = 4.55 years Epoch = 2039 Feb. 21.0 TT T = 2039 Mar. 5.53502 TT Peri. = 276.78329 e = 0.7256065 Node = 358.43893 2000.0 q = 0.7435204 AU Incl. = 2.47718 a = 2.7096870 AU n = 0.22096597 P = 4.46 years Epoch = 2043 Aug. 19.0 TT T = 2043 Aug. 19.84940 TT Peri. = 276.87452 e = 0.7264711 Node = 358.34619 2000.0 q = 0.7406654 AU Incl. = 2.47811 a = 2.7078136 AU n = 0.22119531 P = 4.46 years NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2026 CBAT 2026 July 15 (CBET 5716) Daniel W. E. Green