Electronic Telegram No. 5091 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 P/2021 W2 = P/1997 B1 (KOBAYASHI) M. Rudenko, Minor Planet Center, reports on MPEC 2022-A164 that an apparently asteroidal object found on CCD images obtained on Jan. 11 UT with the 1.04-m f/1.8 Schmidt telescope at the XuYi Station of Purple Mountain Observatory, and reported as a possible near-earth candidate, has been identified by the MPC as an accidental recovery of comet P/1997 B1 (cf. IAUCs 6553, 6554). The MPC identified three observations in the "isolated tracklet file" that had been obtained on 2021 Nov. 29.6 with the 2.25-m Bok reflector at Kitt Peak, and P. Veres (MPC) then requested R. Weryk (Department of Physics and Astronomy, University of Western Ontario) to look at Pan-STARRS CCD images for possible additional observations. Weryk identified four 45-s w-band survey images of the comet taken on 2022 Jan. 7 in 1".3 seeing with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala, noting a very condensed 1".5 coma with a straight 2" tail in p.a. 270 degrees. Weryk also found images taken with the Pan-STARRS2 reflector on four nights in 2021 Nov. (9.54, 9.56, 13.637, 18.539, and 19.547), as well as on five nights also in Nov. with the Pan-STARRS1 telescope (all presumably stellar in appearance). The available astrometry are tabulated below. 2021 UT R.A. (2000) Decl. Mag. Nov. 9.54424 8 26 01.12 +31 14 34.5 22.7 9.55629 8 26 01.93 +31 14 32.7 22.3 11.64771 8 28 25.10 +31 09 21.3 22.9 13.63702 8 30 37.18 +31 04 25.9 22.3 13.64565 8 30 37.69 +31 04 24.9 22.4 18.53859 8 35 43.52 +30 52 28.3 22.2 18.56432 8 35 44.98 +30 52 25.0 21.8 18.58778 8 35 46.37 +30 52 21.6 22.3 19.54677 8 36 42.94 +30 50 02.7 22.1 19.55147 8 36 43.21 +30 50 02.0 21.8 20.52081 8 37 39.16 +30 47 42.3 22.5 29.45542 8 45 16.01 +30 26 57.8 22.0 29.46030 8 45 16.24 +30 26 57.2 21.7 29.46517 8 45 16.42 +30 26 56.4 21.7 29.47001 8 45 16.64 +30 26 55.9 21.8 2022 UT R.A. (2000) Decl. Mag. Jan. 7.38147 8 52 44.76 +28 56 39.7 20.0 7.39370 8 52 44.45 +28 56 37.6 20.0 7.40593 8 52 44.16 +28 56 35.4 20.3 7.41808 8 52 43.84 +28 56 33.3 20.4 11.66774 8 50 51.54 +28 42 18.5 19.9 11.68188 8 50 51.05 +28 42 15.9 20.0 11.69602 8 50 50.59 +28 42 12.0 19.4 The residuals of the recovery observations on 2021 Nov.29 were -0.48 deg in R.A. and +0.25 deg in Decl. from the prediction by T. Kobayashi (Oizumi, Gunma-ken, Japan) in NK 3978 and the ICQ's 2021 Comet Handbook, with the indicated correction to the time of perihelion being Delta(T) = +1.13 days. S. Nakano (CBAT) provides the following linked orbital elements from 257 observations spanning 1997-2022 (mean residual 0".5), noting that there are no close approaches to any major planets, and no other observations in archival astrometry were found. Epoch = 1997 Mar. 13.0 TT T = 1997 Mar. 2.35266 TT Peri. = 183.34246 e = 0.7607715 Node = 329.06412 2000.0 q = 2.0545736 AU Incl. = 12.34988 a = 8.5883323 AU n = 0.03915983 P = 25.17 years Epoch = 2022 Apr. 11.0 TT T = 2022 Mar. 29.95157 TT Peri. = 183.31873 e = 0.7604797 Node = 328.88221 2000.0 q = 2.0562357 AU Incl. = 12.33954 a = 8.5848060 AU n = 0.03918396 P = 25.15 years Epoch = 2047 June 19.0 TT T = 2047 June 5.23153 TT Peri. = 183.38544 e = 0.7610427 Node = 328.71583 2000.0 q = 2.0602366 AU Incl. = 12.32303 a = 8.6217762 AU n = 0.03893220 P = 25.32 years The comet is a couple of magnitudes fainter than the power-law parameters suggest from the 1997 observations (which, however, were all made closer to and after perihelion in 1997 than the 2021-2022 observations). While assuming that an outburst made have occurred in 1997, an average absolute magnitude is assumed for the ephemeris magnitudes below (H = 15.0, 2.5n = 10). Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2022 01 01 08 54.63 +29 14.8 1.342 2.249 150.2 12.5 19.2 2022 01 11 08 51.18 +28 44.7 1.259 2.210 160.1 8.7 18.9 2022 01 21 08 45.41 +28 03.1 1.200 2.174 168.8 5.0 18.8 2022 01 31 08 38.40 +27 06.0 1.166 2.143 169.9 4.6 18.6 2022 02 10 08 31.63 +25 52.0 1.157 2.116 161.7 8.4 18.6 2022 02 20 08 26.56 +24 22.9 1.171 2.094 151.6 13.0 18.6 2022 03 02 08 24.22 +22 42.7 1.206 2.077 141.7 17.2 18.6 2022 03 12 08 25.18 +20 55.6 1.260 2.065 132.5 20.8 18.6 2022 03 22 08 29.50 +19 04.9 1.328 2.058 124.0 23.7 18.8 2022 04 01 08 36.86 +17 12.4 1.409 2.056 116.2 25.8 18.9 2022 04 11 08 46.88 +15 18.5 1.501 2.060 109.2 27.3 19.0 2022 04 21 08 59.03 +13 23.0 1.601 2.069 102.7 28.3 19.2 2022 05 01 09 12.87 +11 25.7 1.708 2.083 96.8 28.7 19.3 2022 05 11 09 28.01 +09 26.0 1.821 2.103 91.3 28.7 19.5 2022 05 21 09 44.10 +07 23.9 1.940 2.127 86.1 28.3 19.7 2022 05 31 10 00.86 +05 19.6 2.063 2.155 81.2 27.7 19.9 2022 06 10 10 18.10 +03 13.2 2.190 2.188 76.5 26.8 20.1 2022 06 20 10 35.64 +01 05.5 2.321 2.225 71.9 25.7 20.3 2022 06 30 10 53.37 -01 03.1 2.454 2.266 67.3 24.5 20.5 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 January 12 (CBET 5091) Daniel W. E. Green