Electronic Telegram No. 5728 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/2026 P1 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in images obtained on Aug. 9 with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala (discovery observations tabulated below). Four stacked 45-s w-band survey images taken in 1".2-1".5 seeing show a very condensed head of size 1".7 (full-width-at- half-maximum) with a tail > 50" long towards p.a. 245 degrees. 2026 UT R.A. (2000) Decl. Mag. Aug. 9.47639 23 20 58.18 -12 17 43.1 20.4 9.48775 23 20 57.95 -12 17 44.2 20.9 9.49908 23 20 57.73 -12 17 45.3 20.3 9.51043 23 20 57.50 -12 17 46.4 20.9 9.61901 23 20 55.36 -12 17 56.3 20.4 After the comet was posted to the Minor Planet Center's PCCP webpage, H. Sato (Bunkyo-ku, Tokyo, Japan) wrote that nine stacked 60-s CCD exposures taken remotely with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW, Australia, on Aug. 13.7 UT show a moderately condensed coma 8" in diameter with a wide tail 15" long toward p.a. 240 degrees; the magnitude was 19.7 as measured within a circular aperture of radius 4".3. The available astrometry appears on MPEC 2026-Q98. The following orbital elements by S. Nakano (Central Bureau) are from 117 observations spanning 2026 Aug. 9-25 (mean residual 0".3). There have been no close approaches to major planets since 1960. T = 2026 Nov. 28.27120 TT Peri. = 338.03374 e = 0.5365389 Node = 19.43442 2000.0 q = 3.6136183 AU Incl. = 8.48009 a = 7.7970267 AU n = 0.04527000 P = 21.77 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 12.5 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2026 07 19 23 24.11 -11 57.6 2.998 3.718 128.6 12.3 19.4 2026 07 29 23 23.54 -12 03.4 2.884 3.703 138.1 10.5 19.3 2026 08 08 23 21.41 -12 15.5 2.790 3.689 148.0 8.4 19.3 2026 08 18 23 17.87 -12 31.9 2.718 3.676 158.1 5.9 19.2 2026 08 28 23 13.25 -12 49.9 2.671 3.665 167.8 3.3 19.1 2026 09 07 23 07.99 -13 06.2 2.652 3.654 173.0 1.9 19.1 2026 09 17 23 02.62 -13 17.9 2.661 3.645 166.2 3.8 19.1 2026 09 27 22 57.72 -13 22.2 2.697 3.637 156.2 6.4 19.1 2026 10 07 22 53.78 -13 17.4 2.759 3.630 145.8 8.9 19.2 2026 10 17 22 51.19 -13 02.6 2.844 3.624 135.6 11.1 19.2 2026 10 27 22 50.22 -12 37.5 2.948 3.620 125.7 12.9 19.3 2026 11 06 22 50.94 -12 02.7 3.068 3.617 116.2 14.2 19.4 2026 11 16 22 53.37 -11 18.7 3.199 3.615 107.0 15.2 19.5 2026 11 26 22 57.39 -10 26.5 3.338 3.614 98.2 15.7 19.6 2026 12 06 23 02.86 -09 27.0 3.482 3.614 89.7 15.8 19.7 2026 12 16 23 09.63 -08 20.9 3.627 3.616 81.5 15.6 19.8 2026 12 26 23 17.51 -07 09.0 3.770 3.618 73.6 15.1 19.8 2027 01 05 23 26.35 -05 52.3 3.910 3.622 66.0 14.4 19.9 2027 01 15 23 35.99 -04 31.4 4.043 3.627 58.5 13.4 20.0 2027 01 25 23 46.30 -03 07.0 4.168 3.634 51.2 12.2 20.1 2027 02 04 23 57.16 -01 39.9 4.283 3.641 44.2 10.9 20.1 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2026 CBAT 2026 August 25 (CBET 5728) Daniel W. E. Green