Electronic Telegram No. 5187 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/2022 U2 (ATLAS) An apparently asteroidal object discovered on CCD images taken on Oct. 25 UT with a 0.5-m f/2 Schmidt reflector at Mauna Loa, Hawaii, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program has been found to show cometary appearance by CCD astrometrists elsewhere. The discovery observations are tabulated below. 2022 UT R.A. (2000) Decl. Mag. Oct. 25.21247 19 19 35.70 +69 24 26.8 19.1 25.21675 19 19 35.41 +69 24 25.6 19.1 25.22605 19 19 33.91 +69 24 20.8 19.1 25.23995 19 19 31.74 +69 24 14.0 19.2 Eight stacked 120-s exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) with a 0.43-m f/6.8 astrograph located at Mayhill, NM, USA, on Oct. 26.1 UT show a strongly condensed object with an outer coma 12" in diameter and no tail; the magnitude was 18.9 as measured within a circular aperture of radius 7".6. Fifty-eight stacked 60-s exposures taken on Oct. 27.8 by L. Buzzi (Varese, Italy) with a 0.84-m f/3.5 reflector (measured by Buzzi and A. Aletti) show the comet as having a softer aspect with respect to nearby stars, with a condensed coma 7" wide and with a faint, round outer coma up to 15" in size but with no clear tail. Fifteen stacked 30-s exposures taken remotely on Oct. 29.1 by K. Yoshimoto (Kumage, Yamaguchi, Japan) with a 0.43-m f/6.8 reflector located at Mayhill show a very diffuse coma 48" in diameter and of total mag 17.4 with no tail. Fifteen 120-s unfiltered exposures taken on Nov. 1.8 by F. Kugel with a 0.4-m f/2.8 reflector at Dauban, France, show a total magnitude of 18.0 in an aperture of radius 0'.2 (and mag 19.0 in an aperture of radius 5".8 = 7 pixels at 0".8/pixel). Sixteen 180-s green- filtered images taken on Nov. 2.8 by M. Jaeger with a 0.41-m f/3.2 reflector at Oed, Austria, show a diffuse coma of size 180" ang total mag 16.1 with no tail. R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports that four 45-s i-band survey images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on Nov. 2.23-2.27 show a condensed but apparently "fuzzy" head of size 1".4 (full-width-at- half-maximum) in 1".1 seeing, adding that there is perhaps a broad tail about 1" long spanning p.a. 60-160 degrees. The available astrometry appears on MPEC 2022-V66. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 151 observations spanning Oct. 25-Nov. 2 (mean residual 0".5). T = 2023 Jan. 14.66104 TT Peri. = 147.52199 Node = 304.87714 2000.0 q = 1.3372839 AU Incl. = 48.56633 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 15.5 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2022 09 18 21 47.12 +69 05.3 1.634 2.145 106.2 26.7 19.2 2022 09 28 21 02.04 +70 33.8 1.549 2.044 104.4 28.4 18.9 2022 10 08 20 16.96 +70 49.7 1.471 1.945 102.1 30.2 18.6 2022 10 18 19 39.57 +70 10.7 1.399 1.849 99.7 32.1 18.4 2022 10 28 19 13.52 +69 05.2 1.328 1.757 97.3 34.1 18.1 2022 11 07 18 58.58 +68 01.6 1.255 1.670 95.4 36.2 17.8 2022 11 17 18 53.18 +67 22.1 1.176 1.589 94.1 38.4 17.5 2022 11 27 18 56.44 +67 24.2 1.091 1.517 93.6 40.5 17.1 2022 12 07 19 08.96 +68 24.1 0.998 1.454 94.3 42.5 16.8 2022 12 17 19 34.82 +70 35.6 0.899 1.403 96.2 44.2 16.4 2022 12 27 20 28.09 +74 02.8 0.798 1.366 99.6 45.2 16.1 2023 01 06 22 31.76 +77 29.8 0.701 1.343 104.5 45.1 15.8 2023 01 16 01 54.59 +74 50.6 0.623 1.337 110.7 43.5 15.5 2023 01 26 03 56.85 +62 52.0 0.581 1.348 116.5 40.8 15.4 2023 02 05 04 53.60 +46 51.8 0.592 1.374 119.0 38.9 15.5 2023 02 15 05 26.92 +31 45.1 0.662 1.415 116.9 38.5 15.8 2023 02 25 05 50.98 +19 55.8 0.777 1.470 112.0 38.6 16.3 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 November 3 (CBET 5187) Daniel W. E. Green