Electronic Telegram No. 5048 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/2021 S2 = P/2012 TK_8 (TENAGRA) E. Schwab, Egelsbach, Germany, reports his recovery of this comet (cf. CBET 3262) on CCD images that he took with the 0.8-m f/3 Schmidt telescope at Calar Alto, Spain, in a program with D. Koschny, M. Micheli, and E. Petrescu. On each of the two nights, twelve 60-s stacked exposures show a tail about 10" long in p.a. 270 degrees. The astrometry is tabulated below. 2021 UT R.A. (2000) Decl. Mag. Observer Sept.30.15890 4 24 05.53 +28 23 08.0 20.0 Schwab 30.17118 4 24 05.71 +28 23 09.5 19.9 " 30.18346 4 24 05.91 +28 23 10.9 20.0 " Oct. 1.15890 4 24 19.65 +28 24 39.6 19.7 " 1.17119 4 24 19.83 +28 24 40.7 19.8 " 1.18348 4 24 19.96 +28 24 42.2 19.8 " The residuals for the recovery observations are +5'.9 in R.A. and +0'.4 in Decl. from the prediction in NK 2685 and in the ICQ's 2020 and 2021 Comet Handbooks, with a corresponding correction of Delta(T) = -0.38 day. The following linked orbital elements by S. Nakano (CBAT) are from 68 observations spanning 2012-2021 (mean residual 0".4). These indicate that the comet passed 0.72 AU from Jupiter on 1983 Jan. 14 UT. A search of archival astrometry files produced no additional observations of this comet. Epoch = 2013 May 28.0 TT T = 2013 May 10.57375 TT Peri. = 128.20732 e = 0.2620587 Node = 289.72361 2000.0 q = 3.0909444 AU Incl. = 6.29547 a = 4.1886048 AU n = 0.11497410 P = 8.57 years Epoch = 2021 Nov. 2.0 TT T = 2021 Oct. 25.70805 TT Peri. = 128.03139 e = 0.2742119 Node = 288.96571 2000.0 q = 2.9954405 AU Incl. = 6.33997 a = 4.1271557 AU n = 0.11755140 P = 8.38 years Epoch = 2030 Apr. 9.0 TT T = 2030 Mar. 27.89477 TT Peri. = 128.27057 e = 0.2729671 Node = 288.88502 2000.0 q = 3.0118429 AU Incl. = 6.33180 a = 4.1426503 AU n = 0.11689251 P = 8.43 years Epoch = 2038 Aug. 5.0 TT T = 2038 Aug. 24.58689 TT Peri. = 128.40087 e = 0.2743588 Node = 288.81931 2000.0 q = 2.9933793 AU Incl. = 6.34223 a = 4.1251509 AU n = 0.11763710 P = 8.38 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 14.0 and 2.5n = 7.5 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2021 09 23 04 21.72 +28 10.3 2.485 3.000 111.4 18.1 19.6 2021 10 03 04 24.70 +28 27.3 2.364 2.998 120.4 16.7 19.4 2021 10 13 04 25.23 +28 37.2 2.255 2.996 130.0 14.8 19.3 2021 10 23 04 23.27 +28 39.0 2.162 2.995 140.2 12.3 19.2 2021 11 02 04 18.97 +28 31.4 2.089 2.996 150.9 9.3 19.2 2021 11 12 04 12.78 +28 13.3 2.040 2.997 161.8 5.9 19.1 2021 11 22 04 05.43 +27 45.1 2.018 2.999 171.5 2.8 19.1 2021 12 02 03 57.86 +27 08.7 2.025 3.002 170.6 3.1 19.1 2021 12 12 03 51.03 +26 27.3 2.060 3.006 160.5 6.3 19.2 2021 12 22 03 45.77 +25 45.4 2.121 3.010 149.4 9.6 19.2 2022 01 01 03 42.62 +25 07.0 2.207 3.016 138.6 12.4 19.3 2022 01 11 03 41.87 +24 35.3 2.313 3.022 128.3 14.8 19.4 2022 01 21 03 43.55 +24 11.7 2.435 3.029 118.4 16.6 19.5 2022 01 31 03 47.53 +23 56.6 2.568 3.038 109.1 17.8 19.7 2022 02 10 03 53.63 +23 49.2 2.710 3.046 100.4 18.6 19.8 2022 02 20 04 01.57 +23 48.3 2.856 3.056 92.1 18.9 19.9 2022 03 02 04 11.12 +23 52.2 3.004 3.067 84.2 18.8 20.0 2022 03 12 04 22.06 +23 59.1 3.152 3.078 76.7 18.3 20.2 2022 03 22 04 34.16 +24 07.5 3.296 3.090 69.5 17.6 20.3 2022 04 01 04 47.23 +24 15.8 3.434 3.103 62.5 16.6 20.4 2022 04 11 05 01.11 +24 22.5 3.567 3.116 55.8 15.4 20.5 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2021 CBAT 2021 October 4 (CBET 5048) Daniel W. E. Green