Electronic Telegram No. 5038 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 P5 = P/2015 Q1 (SCOTTI) On Aug. 3, F. Kugel posted (on the "ICQ Comet Observations" forum on Facebook) a CCD image taken on Aug. 2.96 UT at Dauban, Banon, France, with a 0.4-m f/2.8 reflector showing a recovery of comet P/2015 Q1 (cf. CBET 4138; later shown to be a periodic comet). Thirty-five 90-s CCD exposures taken by Kugel on Aug. 7.0 show a coma of diameter 5" and a short tail in p.a. 230 degrees. His astrometry over three nights is tabulated below. 2021 UT R.A. (2000) Decl. Mag. Observer Aug. 2.95741 22 00 24.21 +19 46 43.4 20.3 Kugel 2.99251 22 00 23.12 +19 46 44.0 21.0 " 3.02743 22 00 22.03 +19 46 44.6 19.8 " 7.02411 21 58 14.27 +19 44 02.8 20.7 " 7.04724 21 58 13.44 +19 44 01.0 20.9 " 7.07127 21 58 12.57 +19 43 58.8 20.4 " 16.04037 21 52 34.79 +19 15 31.2 20.4 " 16.06334 21 52 33.82 +19 15 23.9 21.0 " 16.08740 21 52 32.82 +19 15 16.6 21.9 " Additional astrometry from 2021 appear on MPEC 2021-Q75. The following 2002 NEAT observations of this comet, obtained with the 1.2-m Schmidt telescope at Palomar, were found and measured by R. Matson and published on MPEC 2021-R75: 2002 UT R.A. (2000) Decl. Mag. Nov. 16.27773 4 02 24.02 - 3 38 44.5 19.5 16.30167 4 02 23.15 - 3 39 10.9 19.6 16.34359 4 02 21.65 - 3 39 58.4 19.0 The residuals of the recovery observations on 2021 Aug. 2 were +6'.7 in R.A. and +1'.2 in Decl. from the prediction in NK 3984 and in the ICQ's 2020 and 2021 Comet Handbooks, with a corresponding correction of Delta(T) = -0.25 day. The residuals of the 2002 observations were +22" mainly in R.A. from a linked orbit (2015-2021) on NK 4519, with a corresponding correction of Delta(T) = -0.008 day. The following linked orbital elements by S. Nakano (CBAT) are from 359 observations spanning 2002-2021 (mean residual 0".7). The comet passed 0.58 AU and 1.54 AU from Jupiter on 2005 Dec. 2 and 2017 Dec. 8 UT, respectively. Epoch = 2002 Oct. 13.0 TT T = 2002 Oct. 8.13816 TT Peri. = 195.15148 e = 0.4461073 Node = 205.76071 2000.0 q = 1.9503707 AU Incl. = 23.45493 a = 3.5212068 AU n = 0.14916494 P = 6.61 years Epoch = 2009 May 9.0 TT T = 2009 Apr. 30.98772 TT Peri. = 198.75683 e = 0.4893379 Node = 203.37773 2000.0 q = 1.7498483 AU Incl. = 22.65902 a = 3.4266264 AU n = 0.15538316 P = 6.34 years Epoch = 2015 Sept.15.0 TT T = 2015 Sept. 9.15504 TT Peri. = 198.96479 e = 0.4892169 Node = 203.31006 2000.0 q = 1.7516813 AU Incl. = 22.64897 a = 3.4294034 AU n = 0.15519446 P = 6.35 years Epoch = 2022 Mar. 2.0 TT T = 2022 Feb. 13.36773 TT Peri. = 199.85616 e = 0.4776873 Node = 202.84639 2000.0 q = 1.8136825 AU Incl. = 22.39218 a = 3.4724073 AU n = 0.15232041 P = 6.47 years Epoch = 2028 Aug. 17.0 TT T = 2028 Aug. 9.23783 TT Peri. = 199.98018 e = 0.4766251 Node = 202.79615 2000.0 q = 1.8208697 AU Incl. = 22.36768 a = 3.4790924 AU n = 0.15188159 P = 6.49 years Epoch = 2035 Feb. 2.0 TT T = 2035 Feb. 3.36281 TT Peri. = 199.84795 e = 0.4755591 Node = 202.78295 2000.0 q = 1.8274108 AU Incl. = 22.35073 a = 3.4844931 AU n = 0.15152862 P = 6.50 years The astrometric CCD magnitudes indicate that the comet was intrinsically brighter in 2015-2016 than in 2002 and 2021 by about 3 magnitudes; the ephemeris below uses photometric power-law parameters H = 15.5 and 2.5n = 10 for the magnitudes, which follow the 2002 and 2021 brightness data. Close photometric monitoring of the comet during the remainder of the current return is encouraged. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2021 08 14 21 53.94 +19 24.9 1.464 2.371 145.8 13.9 20.1 2021 08 24 21 47.01 +18 23.2 1.393 2.323 149.8 12.6 19.9 2021 09 03 21 40.06 +16 41.8 1.344 2.276 150.4 12.6 19.7 2021 09 13 21 34.21 +14 25.9 1.316 2.230 147.2 14.1 19.6 2021 09 23 21 30.53 +11 46.4 1.311 2.185 141.2 16.7 19.5 2021 10 03 21 29.74 +08 56.8 1.326 2.142 133.6 19.8 19.4 2021 10 13 21 32.25 +06 10.1 1.358 2.100 125.4 22.8 19.4 2021 10 23 21 38.11 +03 37.5 1.405 2.060 117.3 25.4 19.4 2021 11 02 21 47.13 +01 25.9 1.463 2.022 109.4 27.6 19.4 2021 11 12 21 59.02 -00 20.7 1.529 1.987 102.0 29.2 19.4 2021 11 22 22 13.39 -01 40.6 1.602 1.954 95.0 30.2 19.4 2021 12 02 22 29.86 -02 34.5 1.678 1.924 88.5 30.8 19.5 2021 12 12 22 48.10 -03 03.5 1.756 1.897 82.4 31.0 19.5 2021 12 22 23 07.76 -03 10.0 1.836 1.873 76.7 30.7 19.5 2022 01 01 23 28.58 -02 56.5 1.916 1.853 71.4 30.2 19.6 2022 01 11 23 50.34 -02 25.8 1.995 1.837 66.4 29.4 19.6 2022 01 21 00 12.85 -01 40.9 2.073 1.825 61.7 28.3 19.7 2022 01 31 00 35.95 -00 44.8 2.150 1.818 57.3 27.1 19.8 2022 02 10 00 59.56 +00 19.6 2.225 1.814 53.1 25.8 19.8 2022 02 20 01 23.55 +01 29.3 2.299 1.815 49.2 24.4 19.9 2022 03 02 01 47.88 +02 41.3 2.372 1.820 45.5 22.8 20.0 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2021 CBAT 2021 September 17 (CBET 5038) Daniel W. E. Green