Electronic Telegram No. 5109 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 E2 (ATLAS) An apparently asteroidal object discovered on CCD images taken on Mar. 7 UT with a 0.5-m f/2 Schmidt reflector at Rio Hurtado, Chile, 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 after it was posted on the Minor Planet Center's PCCP webpage. The discovery observations are tabulated below, together with ATLAS observations made with the same telescope (and reported to the MPC on Feb. 23, but identified later as being this comet). 2022 UT R.A. (2000) Decl. Mag. Feb. 23.24494 10 34 26.48 -32 31 49.8 18.9 23.24993 10 34 26.29 -32 31 48.0 18.7 23.26160 10 34 25.88 -32 31 46.0 18.5 23.26430 10 34 25.77 -32 31 45.2 18.4 Mar. 7.11970 10 26 12.49 -31 40 11.6 18.7 7.12311 10 26 12.32 -31 40 11.5 19.0 7.12829 10 26 12.13 -31 40 09.1 19.1 7.16571 10 26 10.55 -31 39 57.4 18.5 Fourteen stacked 60-s CCD exposures taken on Mar. 9.6 UT by T. Ikemura with a 0.38-m f/4.2 reflector at Shinshiro, Japan (and measured by Hirohisa Sato) show a compact, strongly condensed coma about 7" in diameter with no tail; the total magnitude was given as 18.0. E. Guido, Castellammare di Stabia, Italy, writes that twenty-five stacked 120-s unfiltered CCD exposures taken by a large group of observers remotely on Mar. 10.32-10.35 with a "Telescope Live" 0.61-m f/6.5 astrograph located at El Sauce, Chile, show a compact coma about 7" in diameter. Six stacked 120-s CCD exposures taken remotely by H. Sato, Tokyo, Japan, using a 0.51-m f/6.8 astrograph at Siding Spring, NSW, Australia, on Mar. 10.4 reveal a strongly condensed coma 6" in diameter with no tail; the magnitude was 18.6 as measured within a circular aperture of radius 4".9. The available astrometry appears on MPEC 2022-E227. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 64 observations spanning Feb. 23-Mar. 14 (mean residual 0".3). T = 2024 Sept.15.01400 TT Peri. = 41.59689 Node = 125.30769 2000.0 q = 3.6735110 AU Incl. = 137.16584 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 6.5 and 2.5n = 8 for the magnitudes; these parameters suggest that the comet could reach total mag 13 in late 2024. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2022 03 02 10 29.76 -32 04.4 7.551 8.336 140.2 4.4 18.3 2022 03 12 10 22.87 -31 14.5 7.468 8.273 142.0 4.2 18.2 2022 03 22 10 16.29 -30 14.8 7.415 8.210 140.7 4.4 18.2 2022 04 01 10 10.25 -29 07.2 7.391 8.147 136.7 4.8 18.1 2022 04 11 10 04.96 -27 54.1 7.395 8.084 130.7 5.4 18.1 2022 04 21 10 00.57 -26 38.2 7.424 8.021 123.4 6.0 18.1 2022 05 01 09 57.13 -25 22.0 7.473 7.957 115.4 6.6 18.1 2022 05 11 09 54.70 -24 07.8 7.540 7.894 107.0 7.0 18.1 2022 05 21 09 53.23 -22 57.6 7.618 7.831 98.4 7.3 18.1 2022 05 31 09 52.69 -21 52.8 7.703 7.767 89.9 7.5 18.1 2022 06 10 09 52.99 -20 54.5 7.790 7.704 81.4 7.5 18.1 2022 06 20 09 54.05 -20 03.5 7.874 7.641 73.1 7.3 18.0 2022 06 30 09 55.77 -19 19.9 7.951 7.577 65.0 7.0 18.0 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 March 15 (CBET 5109) Daniel W. E. Green