Electronic Telegram No. 5103 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 B4 (BOK) An apparently asteroidal that was reported on CCD images taken on Jan. 29 UT by H. Groeller with the 2.25-m Bok reflector at Kitt Peak as part of a survey collaboration with the Catalina Sky Survey, Spacewatch, and the University of Minnesota (termed the "Bok NEO Survey") has been found by CCD astrometrists elsewhere to show cometary appearance. The comet, whose discovery observations are tabulated below, has been designated C/2022 B4 after the designation "B3" was given to a very unusual, apparently asteroidal object with a nearly parabolic retrograde short-period orbit (A/2022 B3; cf. MPEC 2022-D24). 2022 UT R.A. (2000) Decl. Mag. Observer Jan. 29.46488 10 52 20.35 +38 46 50.7 20.8 Groeller 29.46975 10 52 20.29 +38 46 37.5 21.2 " 29.47461 10 52 20.21 +38 46 24.1 21.1 " 29.48406 10 52 20.08 +38 45 58.1 21.1 " Apparently asteroidal Mt. Lemmon Survey observations made an hour before the Bok Survey observations above were reported to the Minor Planet Center a day later. R. Weryk, Department of Physics and Astronomy, University of Western Ontario, later identified the comet in four 45-s w-band survey images obtained on Feb. 6.4 UT with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala in 1".4 seeing, with a condensed coma of size 1".7 (full-width-at- half-maximum) and no obvious tail. D. D. Balam, Dominion Astrophysical Observatory, National Research Council of Canada, reports that thirty-one stacked 63-s exposures taken by C. E. Spratt, P. Langill, D. W. E. Green, and himself on Feb. 12.3 in 1".9 seeing show a coma of size 2".7 (FWHM) and a short 6".2 spike tail in p.a. 230 degrees. The available astrometry appears on MPEC 2022-D33. The following orbital elements by S. Nakano (Central Bureau) are from 95 observations spanning Jan. 29-Feb. 22 (mean residual 0".4). T = 2022 Jan. 29.89686 TT Peri. = 152.95630 e = 0.9964106 Node = 340.66160 2000.0 q = 1.3796528 AU Incl. = 20.04378 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 20.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2022 01 21 10 50.62 +44 30.9 0.484 1.386 139.0 27.8 19.6 2022 01 26 10 52.26 +41 17.1 0.462 1.381 142.7 25.6 19.4 2022 01 31 10 52.14 +37 36.2 0.445 1.380 147.1 22.8 19.4 2022 02 05 10 50.53 +33 29.8 0.432 1.383 152.0 19.6 19.3 2022 02 10 10 47.84 +29 01.9 0.425 1.389 157.5 15.8 19.3 2022 02 15 10 44.46 +24 19.9 0.425 1.400 163.3 11.7 19.3 2022 02 20 10 40.76 +19 33.4 0.430 1.414 169.1 7.6 19.4 2022 02 25 10 37.09 +14 53.1 0.443 1.431 174.2 4.0 19.5 2022 03 02 10 33.72 +10 28.4 0.462 1.452 174.9 3.5 19.6 2022 03 07 10 30.93 +06 26.3 0.488 1.476 170.5 6.3 19.8 2022 03 12 10 28.88 +02 50.7 0.521 1.503 165.4 9.6 20.0 2022 03 17 10 27.66 -00 17.3 0.559 1.533 160.4 12.6 20.2 2022 03 22 10 27.29 -02 58.9 0.602 1.565 155.7 15.2 20.5 2022 03 27 10 27.76 -05 16.4 0.651 1.599 151.4 17.4 20.7 2022 04 01 10 29.03 -07 12.8 0.704 1.636 147.2 19.3 20.9 2022 04 06 10 31.08 -08 51.5 0.761 1.674 143.4 20.9 21.2 2022 04 11 10 33.84 -10 15.5 0.823 1.715 139.7 22.2 21.5 2022 04 16 10 37.23 -11 27.6 0.889 1.756 136.3 23.3 21.7 2022 04 21 10 41.17 -12 30.1 0.958 1.799 133.0 24.1 21.9 2022 04 26 10 45.59 -13 24.8 1.030 1.844 129.7 24.8 22.2 2022 05 01 10 50.45 -14 13.4 1.106 1.889 126.6 25.3 22.4 2022 05 06 10 55.68 -14 57.3 1.185 1.935 123.6 25.7 22.7 2022 05 11 11 01.25 -15 37.7 1.268 1.983 120.6 26.0 22.9 2022 05 16 11 07.10 -16 15.4 1.353 2.030 117.7 26.2 23.1 2022 05 21 11 13.18 -16 51.0 1.441 2.079 114.8 26.2 23.3 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 February 24 (CBET 5103) Daniel W. E. Green