Electronic Telegram No. 5019 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 N4 Y. Ramanjooloo, Institute for Astronomy, University of Hawaii, reports the discovery of another comet in images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala; four 45-s w-band exposures show a nearly stellar coma in 1".5-1".6 seeing but with a straight, thin, faint tail 10"-12" long in p.a. about 235 degrees. The astrometry is tabulated below, together with one-night Pan-STARRS1 observations from last month that had been submitted as a separate object and were in the Minor Planet Center's "isolated tracklet file". 2021 UT R.A. (2000) Decl. Mag. July 8.53018 23 07 47.20 + 9 16 09.5 22.3 8.54163 23 07 47.49 + 9 16 15.3 22.4 8.55306 23 07 47.77 + 9 16 21.1 22.3 Aug. 9.57479 23 09 45.64 +12 12 27.6 21.7 9.58613 23 09 45.37 +12 12 28.8 21.6 9.59739 23 09 45.15 +12 12 29.9 21.5 9.60859 23 09 44.89 +12 12 31.2 21.5 R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports that three 60-s gri-band images taken on Aug. 10.51 UT by queue observer H. Januszewski and queue coordinator T. Burdullis in 1".0 seeing show this to be a definite comet, with a very condensed coma of size 1".4 (full-width-at-half-maximum) and a straight tail > 14" long in p.a. 230 degrees. After the comet was posted on the Minor Planet Center's PCCP webpage, H. Sato (Tokyo, Japan) writes that twenty-four stacked 60-s CCD exposures taken with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW, Australia, on Aug. 14.6 UT show a stellar appearance; the magnitude was 21.4 as measured within a circular aperture of radius 6".6. The available astrometry appears on MPEC 2021-Q1. The following preliminary two-body orbital elements by S. Nakano (CBAT) are from 15 observations spanning 2021 July 8-Aug. 14 (mean residual 0".3), but the orbit is heavily dependent upon the single-night observations on July 8. No additional archival observations were found. No name is being given to this comet presently because the orbit is like that of a main-belt asteroid. T = 2021 Aug. 28.41732 TT Peri. = 104.52231 e = 0.2439512 Node = 239.24877 2000.0 q = 2.3021364 AU Incl. = 10.06629 a = 3.0449576 AU n = 0.18549500 P = 5.31 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 18.0 and 2.5n = 7. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2021 08 14 23 08.09 +12 18.2 1.402 2.304 144.5 14.8 21.3 2021 08 24 23 02.92 +12 11.1 1.354 2.302 153.3 11.4 21.2 2021 09 03 22 56.45 +11 36.4 1.326 2.302 160.6 8.4 21.1 2021 09 13 22 49.68 +10 37.4 1.322 2.304 163.2 7.3 21.1 2021 09 23 22 43.73 +09 21.7 1.342 2.307 158.9 9.0 21.2 2021 10 03 22 39.55 +07 58.8 1.385 2.311 150.8 12.2 21.3 2021 10 13 22 37.79 +06 38.4 1.449 2.316 141.7 15.5 21.4 2021 10 23 22 38.75 +05 28.4 1.532 2.323 132.5 18.4 21.5 2021 11 02 22 42.40 +04 33.8 1.631 2.331 123.5 20.8 21.6 2021 11 12 22 48.56 +03 57.0 1.742 2.340 115.1 22.5 21.8 2021 11 22 22 56.91 +03 38.8 1.863 2.351 107.0 23.7 21.9 2021 12 02 23 07.10 +03 38.1 1.991 2.362 99.4 24.3 22.1 2021 12 12 23 18.85 +03 53.7 2.124 2.375 92.2 24.5 22.3 2021 12 22 23 31.86 +04 23.5 2.260 2.389 85.3 24.2 22.4 2022 01 01 23 45.89 +05 05.5 2.396 2.404 78.6 23.6 22.6 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2021 CBAT 2021 August 16 (CBET 5019) Daniel W. E. Green