Electronic Telegram No. 5032 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 C/2021 Q6 (PANSTARRS) Y. Ramanjooloo, Institute for Astronomy, University of Hawaii, identified another comet with a condensed coma of diameter 1".5 (in 0".8-1".1 seeing) in four 120-s z-band images obtained on Aug. 22 with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala, with the comment that there might be a very-low-surface-brightness tail at p.a. about 260 degrees. The discovery observations are tabulated below, along with numerous pre-discovery Pan-STARRS1 observations dating back to Jan. 2 that were reported later to the Minor Planet Center. 2021 UT R.A. (2000) Decl. Mag. Jan. 2.29049 2 12 14.02 +33 32 26.0 22.1 3.35078 2 11 52.70 +33 28 55.3 21.9 9.26746 2 10 03.94 +33 09 47.1 22.4 9.27969 2 10 03.73 +33 09 44.7 21.8 9.29186 2 10 03.52 +33 09 42.3 21.9 9.30404 2 10 03.30 +33 09 40.0 22.3 30.24801 2 05 55.37 +32 10 22.5 21.8 31.30372 2 05 48.28 +32 07 47.9 22.1 31.31607 2 05 48.24 +32 07 46.5 21.9 July 28.60384 2 25 08.31 +33 19 41.9 20.8 28.61431 2 25 08.23 +33 19 42.8 21.3 Aug. 19.46971 2 20 04.75 +33 38 19.8 20.8 19.48083 2 20 04.53 +33 38 20.3 21.7 19.49200 2 20 04.31 +33 38 20.7 21.5 19.50315 2 20 04.09 +33 38 20.7 21.3 20.51780 2 19 44.22 +33 38 48.6 21.1 20.53026 2 19 43.96 +33 38 48.6 21.6 20.54271 2 19 43.71 +33 38 48.8 21.3 20.55537 2 19 43.45 +33 38 49.4 21.5 20.63697 2 19 41.82 +33 38 51.2 20.4 22.51958 2 19 03.47 +33 39 34.7 22.2 22.52722 2 19 03.30 +33 39 34.6 22.1 22.53486 2 19 03.16 +33 39 34.8 21.9 22.54342 2 19 02.98 +33 39 35.0 22.1 R. Weryk, Department of Physics and Astronomy, University of Western Ontario, writes that he and R. Wainscoat obtained three 90-s gri-band confirming observations of this comet with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea on Sept. 3.46 UT (queue observer C. Cunningham; coordinators T. Burdullis and N. Manset) that show a very condensed coma of size 1".25 (full-width-at-half-maximum) in 0".5 seeing, along with a straight 1" tail in p.a. 200 degrees. The available astrometry appears on MPEC 2021-R167. The following orbital elements by S. Nakano (CBAT) are from 48 observations spanning 2021 Jan. 2-2021 Sept. 7 (mean residual 0".2), with corresponding original and future values of 1/a being +0.000091 and +0.000055 AU**-1, respectively (mean error +/- 0.000027 AU**-1). The comet will pass 2.03 AU from Saturn on 2024 Aug. 24 UT. Epoch = 2024 Mar. 31.0 TT T = 2024 Mar. 24.83612 TT Peri. = 140.99738 e = 1.0005490 Node = 133.53668 2000.0 q = 8.7098434 AU Incl. = 161.84654 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 7.5 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2021 08 14 02 21.71 +33 35.2 10.117 10.280 96.5 5.6 20.6 2021 08 24 02 18.53 +33 40.0 9.924 10.251 106.1 5.4 20.6 2021 09 03 02 14.52 +33 40.4 9.740 10.222 115.9 5.1 20.5 2021 09 13 02 09.72 +33 35.5 9.571 10.192 125.8 4.6 20.5 2021 09 23 02 04.21 +33 24.7 9.423 10.164 135.6 4.0 20.4 2021 10 03 01 58.12 +33 07.4 9.299 10.135 145.0 3.2 20.4 2021 10 13 01 51.63 +32 43.4 9.205 10.106 153.3 2.5 20.4 2021 10 23 01 44.95 +32 13.2 9.143 10.078 159.0 2.0 20.3 2021 11 02 01 38.30 +31 37.3 9.114 10.050 159.5 2.0 20.3 2021 11 12 01 31.91 +30 56.9 9.120 10.022 154.4 2.4 20.3 2021 11 22 01 25.99 +30 13.5 9.160 9.995 146.1 3.2 20.3 2021 12 02 01 20.69 +29 28.7 9.229 9.967 136.5 3.9 20.3 2021 12 12 01 16.15 +28 44.3 9.325 9.940 126.3 4.6 20.3 2021 12 22 01 12.44 +28 01.7 9.443 9.913 116.0 5.1 20.3 2022 01 01 01 09.59 +27 22.4 9.576 9.886 105.6 5.5 20.4 2022 01 11 01 07.59 +26 47.3 9.720 9.860 95.3 5.7 20.4 2022 01 21 01 06.39 +26 17.1 9.867 9.834 85.2 5.7 20.4 2022 01 31 01 05.94 +25 52.1 10.012 9.808 75.2 5.6 20.4 2022 02 10 01 06.15 +25 32.6 10.150 9.782 65.5 5.3 20.5 2022 02 20 01 06.94 +25 18.4 10.275 9.756 56.0 4.8 20.5 2022 03 02 01 08.20 +25 09.2 10.383 9.731 46.8 4.3 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 September 9 (CBET 5032) Daniel W. E. Green