Electronic Telegram No. 5069 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 V3 = P/2011 UE_215 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in seven 45-s w-band survey images obtained on Nov. 1.5 UT with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala (discovery observations tabulated below) in 1".2 seeing; the comet showed a condensed coma of size 1".6 (full-width-at-half- maximum) and a short 2" tail in p.a. 255 degrees. 2021 UT R.A. (2000) Decl. Mag. Nov. 1.49510 2 51 22.42 +18 23 52.2 21.9 1.49575 2 51 22.40 +18 23 52.2 21.1 1.50902 2 51 21.83 +18 23 49.2 21.2 1.50967 2 51 21.85 +18 23 49.2 21.6 1.52300 2 51 21.32 +18 23 46.5 21.5 1.54607 2 51 20.42 +18 23 41.5 21.2 1.54671 2 51 20.39 +18 23 41.5 21.6 1.54671 2 51 20.39 +18 23 41.5 21.3 Weryk further identified pre-discovery observations obtained with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala on Oct. 13.6 UT (at mag 22.2-22.8) and 29.5 (mag 20.9-21.3), as well as additional Pan-STARRS1 observations on Oct. 14.5 (mag 21.6-22.2) and 26.5 (mag 22.0-22.3). After the comet was posted on the Minor Planet Center's PCCP webpage, H. Sato (Tokyo, Japan) found that twenty-four stacked 60-s CCD exposures taken remotely on Nov. 5.2 UT with a 0.43-m f/6.8 astrograph located near Mayhill, NM, USA, show a strongly condensed coma 6" in diameter with no tail; the magnitude was 20.5 as measured within a circular aperture of radius 5".7. With the longer 2021 arc, MPC staff identified apparently asteroidal CCD observations of this comet in the MPC's "isolated tracklet file" (which is accessible publicly) made with the 1.5-m reflector at Mt. Lemmon on 2012 Jan. 20 (at mag 20.3-20.8) and Feb. 10 (mag 20.5-21.4) and with a Tenagra 0.41-m reflector at Nogales, AZ, USA, on 2012 Dec. 20 (mag 19.7-20.2) and 2013 Jan. 16 (mag 19.6-19.8). After those linkages were made, the MPC staff further identified this comet with an apparently asteroidal object that had been observed on two nights at Mt. Lemmon in 2011 and then given the minor-planet designation 2011 UE_215 (cf. MPS 398552; astrometry tabulated below). 2011 UT R.A. (2000) Decl. Mag. Oct. 24.25632 1 38 01.50 +13 26 18.0 20.9 24.26152 1 38 01.28 +13 26 16.6 21.2 24.26677 1 38 01.10 +13 26 15.2 21.1 24.27197 1 38 00.92 +13 26 13.9 21.1 30.18714 1 34 29.13 +13 02 00.0 21.0 30.19523 1 34 28.84 +13 01 58.1 21.4 30.20325 1 34 28.56 +13 01 55.9 21.1 30.21123 1 34 28.27 +13 01 53.7 21.0 All of the available astrometry appears on MPEC 2021-V173. The following linked orbital elements by S. Nakano (CBAT) are from 61 observations spanning 2011-2021 (mean residual 0".3); the formal error in the period is +/- 0.02 day. The comet passed 0.39 AU from Jupiter on 2007 Dec. 9 UT; prior to that approach, the orbital elements were T = 2004 Apr. 26.1 TT, q = 3.952 AU, e = 0.189, Peri. = 228.7 deg, Node = 268.5 deg, i = 3.8 deg, a = 4.874 AU, P = 10.8 years. Epoch = 2004 Apr. 25.0 TT T = 2004 Apr. 26.09569 TT Peri. = 228.73081 e = 0.1891891 Node = 268.48537 2000.0 q = 3.9520715 AU Incl. = 3.84975 a = 4.8742207 AU n = 0.09158963 P = 10.76 years Epoch = 2012 Nov. 9.0 TT T = 2012 Nov. 27.71364 TT Peri. = 206.85697 e = 0.2557359 Node = 245.91845 2000.0 q = 3.4047654 AU Incl. = 3.69035 a = 4.5746736 AU n = 0.10073118 P = 9.78 years Epoch = 2022 Aug. 9.0 TT T = 2022 Aug. 18.43942 TT Peri. = 206.71614 e = 0.2542778 Node = 245.86721 2000.0 q = 3.4001997 AU Incl. = 3.68935 a = 4.5596066 AU n = 0.10123088 P = 9.74 years Epoch = 2032 June 17.0 TT T = 2032 May 31.33385 TT Peri. = 206.85867 e = 0.2533941 Node = 245.77553 2000.0 q = 3.4234690 AU Incl. = 3.68331 a = 4.5853763 AU n = 0.10037871 P = 9.82 years Epoch = 2042 Mar. 17.0 TT T = 2042 Mar. 30.96990 TT Peri. = 207.09149 e = 0.2531203 Node = 245.61132 2000.0 q = 3.4228786 AU Incl. = 3.68509 a = 4.5829048 AU n = 0.10045992 P = 9.81 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 12.0 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2021 11 02 02 51.05 +18 22.1 2.662 3.650 173.4 1.8 19.7 2021 11 12 02 44.62 +17 45.9 2.648 3.634 174.4 1.5 19.7 2021 11 22 02 38.50 +17 08.9 2.663 3.619 162.9 4.6 19.7 2021 12 02 02 33.29 +16 34.5 2.707 3.604 151.5 7.5 19.7 2021 12 12 02 29.50 +16 05.9 2.776 3.590 140.3 10.1 19.8 2021 12 22 02 27.46 +15 45.4 2.868 3.576 129.6 12.2 19.8 2022 01 01 02 27.31 +15 34.2 2.976 3.562 119.3 13.9 19.9 2022 01 11 02 29.07 +15 32.8 3.097 3.549 109.5 15.1 20.0 2022 01 21 02 32.67 +15 40.7 3.227 3.536 100.2 15.9 20.0 2022 01 31 02 37.97 +15 57.0 3.361 3.524 91.3 16.2 20.1 2022 02 10 02 44.82 +16 20.4 3.496 3.512 82.9 16.2 20.2 2022 02 20 02 53.04 +16 49.4 3.628 3.501 74.8 15.8 20.2 2022 03 02 03 02.48 +17 22.7 3.756 3.491 67.1 15.2 20.3 2022 03 12 03 12.98 +17 58.7 3.876 3.481 59.6 14.3 20.4 2022 03 22 03 24.42 +18 36.1 3.987 3.471 52.4 13.2 20.4 2022 04 01 03 36.67 +19 13.7 4.088 3.462 45.5 11.9 20.5 2022 04 11 03 49.63 +19 50.4 4.177 3.454 38.8 10.5 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 November 9 (CBET 5069) Daniel W. E. Green