Electronic Telegram No. 5171 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 R2 (ATLAS) Alan Fitzsimmons, Queen's University, Belfast, reports the discovery of a comet in four 30-s CCD images taken on Sept. 14.6 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. Stacked images show a straight tail 30" long in p.a. 280 degrees; the coma size was 9".0 (full-width-at-half-maximum) in 4".5 seeing. The discovery observations are tabulated below. 2022 UT R.A. (2000) Decl. Mag. Sept.14.59866 7 46 12.55 +21 36 37.2 17.6 14.60189 7 46 13.64 +21 36 43.3 16.3 14.62132 7 46 21.19 +21 37 16.3 16.8 14.63380 7 46 25.88 +21 37 37.2 16.9 After the comet was posted on the Minor Planet Center's PCCP webpage, other CCD astrometrists have commented on the cometary appearance. Eighteen stacked 30-s exposures taken remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) with a 0.25-m f/3.4 reflector at Mayhill, NM, USA, on Sept. 15.44 UT show a strongly condensed coma 20" in diameter and a 50" tail toward p.a. 270 degrees; the magnitude was 16.7 as measured within a circular aperture of radius 10".0. Thirty-two stacked 20-s exposures taken remotely by Sato with a 0.43-m f/6.8 astrograph at Mayhill on Sept. 17.4 show a strongly condensed coma 20" in diameter with a tail 1'.5 long toward p.a. 280 degrees; the magnitude was 16.4 as measured within a circular aperture of radius 11".4. Seventeen stacked 30-s exposures taken remotely by K. Yoshimoto (Kumage, Yamaguchi, Japan) with a 0.43-m f/6.8 reflector located at Mayhill on Sept. 15.5 show a condensed coma 18" in diameter and a tail 0'.8 long in p.a. 285 deg; the total magnitude was measured to be 17.3. Forty 30-s exposures taken by A. Aletti with a 0.20-m f/4 reflector at Varese, Italy, on Sept. 16.1 show a condensed coma 10" wide and a straight, faint tail at least 30" long in p.a. 280 degrees; the total magnitude was measured as 16.9. One-hundred-twenty 15-s exposures taken by L. Buzzi with a 0.84-m f/3.5 reflector at Varese (and measured by Buzzi and Aletti) on Sept. 18.1 show a moderately condensed 12" coma and a tail 90" long in p.a. 283 deg. F. D. Romanov found a condensed coma 7" in diameter and a broad tail 12" long in p.a. 285 degrees on forty stacked 30-s exposures (with Luminance filter) taken remotely on Sept. 16.3 with a 0.61-m f/6.5 corrected Dall-Kirkham reflector at the Burke-Gaffney Observatory of Saint Mary's University in Halifax, NS, Canada. Eight 30-s unfiltered exposures taken by F. Kugel with a 0.4-m f/2.8 reflector at Dauban, France, on Sept. 17.13-17.17 show a tail 1' long in p.a. 280 degrees; the magnitude was 17.7 in an aperture of radius 5". E. Guido, Castellammare di Stabia, Italy, writes that he has measured forty stacked unfiltered 90-s exposures taken remotely on Sept. 17.2 by a large group of observers using a "Telescope Live" 0.10-m f/3.6 refractor at Oria, Spain, which show a compact coma about 15" in diameter (mag 16.6-16.8) and a tail 50" long in p.a. 280 degrees. M. Jaeger, Vienna, writes that seven 60-s exposures taken on Sept. 18.1 with a 28-cm f/2.2 reflector located at Stixendorf show a 35" outer coma and a bright 15" inner coma (total mag 16.0) and a 3' tail in p.a. 276 degrees. The available astrometry appears on MPEC 2022-S87. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 110 observations spanning Sept. 14-19 (mean residual 0".5). T = 2022 Oct. 25.20937 TT Peri. = 78.39173 Node = 60.42696 2000.0 q = 0.6323258 AU Incl. = 52.93164 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 16.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2022 08 09 05 19.44 +07 17.3 1.887 1.600 58.0 32.5 19.0 2022 08 14 05 32.99 +08 47.0 1.777 1.525 58.9 34.7 18.7 2022 08 19 05 47.87 +10 24.6 1.668 1.449 59.7 37.1 18.4 2022 08 24 06 04.38 +12 11.1 1.561 1.373 60.1 39.7 18.1 2022 08 29 06 22.92 +14 07.6 1.459 1.297 60.2 42.5 17.7 2022 09 03 06 43.99 +16 14.2 1.361 1.220 59.8 45.6 17.4 2022 09 08 07 08.20 +18 29.9 1.271 1.144 58.9 49.0 17.0 2022 09 13 07 36.29 +20 51.3 1.190 1.068 57.5 52.6 16.6 2022 09 18 08 08.93 +23 10.7 1.121 0.994 55.4 56.4 16.2 2022 09 23 08 46.60 +25 15.0 1.068 0.921 52.7 60.0 15.9 2022 09 28 09 29.09 +26 45.5 1.034 0.852 49.5 63.3 15.5 2022 10 03 10 15.10 +27 21.6 1.023 0.788 45.8 65.6 15.2 2022 10 08 11 02.22 +26 48.5 1.034 0.731 42.1 66.4 15.0 2022 10 13 11 47.60 +25 03.8 1.070 0.685 38.5 65.1 14.8 2022 10 18 12 28.97 +22 18.1 1.126 0.651 35.1 61.5 14.8 2022 10 23 13 05.24 +18 49.7 1.199 0.634 31.9 56.0 14.8 2022 10 28 13 36.40 +14 57.8 1.284 0.635 29.0 49.3 15.0 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 September 20 (CBET 5171) Daniel W. E. Green