Electronic Telegram No. 5157 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 O1 (ATLAS) A. Fitzsimmons reported the discovery of a comet on CCD images taken on July 26 UT with a 0.5-m f/2 Schmidt reflector at Sutherland, South Africa, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program, noting a non-stellar appearance in four 30-s images, with an apparent coma of size 8".1 (full-width-at-half-maximum) in 5".5 seeing; stacked images suggest a possible faint elongation toward p.a. 205 degrees. ATLAS reported a second independent discovery on July 29 on images taken with an ATLAS 0.5-m f/2 Schmidt reflector at Rio Hurtado, Chile. The discovery observations are tabulated below: 2022 UT R.A. (2000) Decl. Mag. July 26.13013 3 41 01.36 -59 29 36.5 19.3 26.13325 3 41 01.53 -59 29 36.8 19.1 26.13880 3 41 01.55 -59 29 38.9 19.0 26.14931 3 41 01.74 -59 29 41.3 19.2 29.25222 3 42 03.62 -59 38 51.5 19.0 29.25267 3 42 03.43 -59 38 52.6 19.2 29.25312 3 42 03.47 -59 38 51.7 19.3 29.25357 3 42 03.55 -59 38 51.5 19.4 After the comet was posted on the Minor Planet Center's PCCP webpage, other CCD astrometrists have reported cometary appearance to the Central Bureau. Sixty stacked 60-s exposures taken by A. Aletti, F. Bellini, L. Buzzi, and G. Galli with a 0.36-m f/8.4 reflector at Hakos, Namibia, on July 29.14-29.16 UT show a strong, asymmetric central condensation of size 7" x 5" with a broad, faint tail at least 15" long centered at p.a. 185 degrees; the magnitude was given as 19.2. Sixty additional 60-s stacked exposures taken by Aletti et al. on Aug. 3.0 show a condensed coma 8" wide with a broad, faint tail at least 20" long centered at p.a. 190 degrees, with the object's magnitude given as 19.0. Ten stacked 60-s exposures taken remotely by H. Sato (Tokyo, Japan) with a 0.51-m f/6.8 astrograph at Siding Spring, NSW, Australia, on Aug. 1.8 show a strongly condensed coma 8" in diameter with a hint of a tail 15" long toward p.a. 210 degrees; the magnitude was 18.2 as measured within a circular aperture of radius 6".6. E. Bryssinck, Kruibeke, Belgium, writes that fifteen stacked 180-s luminance-filtered exposures taken remotely by M. Rocchetto, E. Guido, G. Milani, A. Valvasori, and himself on Aug. 4.3 with a "Telescope Live" 0.61-m f/6.5 reflector located at Rio Hurtado, Chile, show a strong central condensation with a faint coma of size about 9" and a broad tail 18" long in p.a. spanning 189-230 degrees; the magnitude was 18.7 as measured in a circular aperture of size 5".5. The available astrometry appears on MPEC 2022-Q02. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 50 observations spanning July 26-Aug. 14 (mean residual 0".5). T = 2022 Mar. 12.50417 TT Peri. = 270.65110 Node = 49.75816 2000.0 q = 7.4395997 AU Incl. = 71.05921 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 7.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2022 04 11 02 11.25 -62 21.9 7.703 7.442 71.3 7.3 18.4 2022 04 21 02 22.47 -61 22.1 7.671 7.444 73.3 7.4 18.4 2022 05 01 02 33.36 -60 30.8 7.636 7.446 75.4 7.5 18.4 2022 05 11 02 43.85 -59 48.5 7.598 7.449 77.7 7.6 18.4 2022 05 21 02 53.86 -59 15.5 7.558 7.452 80.2 7.7 18.4 2022 05 31 03 03.33 -58 52.1 7.518 7.456 82.7 7.8 18.4 2022 06 10 03 12.14 -58 38.2 7.476 7.461 85.3 7.8 18.4 2022 06 20 03 20.20 -58 33.8 7.434 7.466 87.9 7.8 18.3 2022 06 30 03 27.39 -58 38.6 7.393 7.472 90.5 7.8 18.3 2022 07 10 03 33.57 -58 52.0 7.354 7.478 93.1 7.8 18.3 2022 07 20 03 38.59 -59 13.2 7.316 7.484 95.6 7.8 18.3 2022 07 30 03 42.28 -59 41.2 7.283 7.491 98.0 7.7 18.3 2022 08 09 03 44.47 -60 14.5 7.253 7.499 100.2 7.6 18.3 2022 08 19 03 44.98 -60 51.3 7.229 7.507 102.1 7.6 18.3 2022 08 29 03 43.65 -61 29.6 7.211 7.516 103.7 7.5 18.3 2022 09 08 03 40.35 -62 06.5 7.201 7.525 105.0 7.4 18.3 2022 09 18 03 35.06 -62 39.2 7.199 7.535 105.8 7.4 18.3 2022 09 28 03 27.85 -63 04.7 7.207 7.545 106.0 7.3 18.3 2022 10 08 03 18.96 -63 19.7 7.224 7.556 105.7 7.3 18.3 2022 10 18 03 08.81 -63 21.7 7.251 7.567 104.8 7.3 18.3 2022 10 28 02 57.96 -63 08.5 7.288 7.579 103.3 7.3 18.3 2022 11 07 02 47.06 -62 39.1 7.335 7.591 101.2 7.4 18.4 2022 11 17 02 36.76 -61 53.4 7.392 7.604 98.6 7.4 18.4 2022 11 27 02 27.60 -60 52.5 7.458 7.617 95.5 7.4 18.4 2022 12 07 02 19.95 -59 38.2 7.531 7.630 92.1 7.4 18.4 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 August 16 (CBET 5157) Daniel W. E. Green