Electronic Telegram No. 5682 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/2026 H1 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in images obtained with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala. The best three 45-s w-band survey images taken in 1".3-1".4 seeing show a condensed head of size 1".9 (full-width-at-half-maximum) with a straight 10" tail in p.a. 160 degrees. The discovery astrometry is tabulated below. 2026 UT R.A. (2000) Decl. Mag. Apr. 19.33506 11 37 00.49 -15 19 19.9 20.2 19.34667 11 37 00.06 -15 19 11.4 20.6 19.35830 11 36 59.64 -15 19 03.3 20.4 19.37001 11 36 59.21 -15 18 55.0 20.5 19.41921 11 36 57.40 -15 18 19.3 20.9 19.41989 11 36 57.37 -15 18 18.9 20.8 Weryk was able to find the comet in earlier images taken with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on Jan. 27.6 UT, when four 45-s w-band survey images taken in 1".5 seeing showed a condensed head of size 1".9 (FWHM) and no tail. He also identified Pan-STARRS2 images from Feb. 25.5 taken in 1".4 seeing, in which one 45-s w-band survey exposure shows a condensed head of size 2".0 (FWHM) with a likely short 3" tail in p.a. 165 degrees. After the comet was posted on the Minor Planet Center's PCCP webpage, H. Sato (Bunkyo-ku, Tokyo, Japan) reported that fourteen stacked 60-s CCD exposures taken remotely on Apr. 20.51 UT with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW, Australia, show a strongly condensed coma of diameter 8" and with no tail; the magnitude was 19.9 as measured within a circular aperture of radius 4".3. The available astrometry appears on MPEC 2026-H102 and includes pre- discovery observations from MPC's "isolated tracklet file" made at Mt. Lemmon on Mar. 22.3 (at mag 19.8-20.5) and Apr. 9.2 UT (mag 20.2-20.3), which were reported separately with two different internal designations without comment. The following orbital elements by S. Nakano (Central Bureau) are from 33 observations spanning 2026 Jan. 27-Apr. 22 (mean residual 0".4), with corresponding "original" and "future" values of 1/a being +0.000321 and +0.000500 (+/- 0.000116) AU**-1. The comet will pass 2.87 AU from Jupiter on 2027 July 30 UT. Epoch = 2026 June 9.0 TT T = 2026 June 13.58036 TT Peri. = 349.65941 e = 1.0007564 Node = 178.72793 2000.0 q = 6.0838348 AU Incl. = 115.59326 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 8.5 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2026 03 21 11 57.76 -21 00.3 5.172 6.112 159.0 3.3 19.9 2026 03 31 11 50.17 -19 08.7 5.153 6.106 161.0 3.0 19.9 2026 04 10 11 43.01 -17 11.0 5.171 6.100 156.1 3.8 19.9 2026 04 20 11 36.61 -15 11.4 5.226 6.096 147.3 5.1 19.9 2026 04 30 11 31.20 -13 13.9 5.314 6.092 137.2 6.4 20.0 2026 05 10 11 26.91 -11 22.2 5.431 6.089 126.7 7.6 20.0 2026 05 20 11 23.80 -09 38.7 5.571 6.086 116.2 8.6 20.1 2026 05 30 11 21.88 -08 05.2 5.728 6.085 105.9 9.2 20.1 2026 06 09 11 21.09 -06 42.3 5.897 6.084 95.8 9.6 20.2 2026 06 19 11 21.34 -05 30.3 6.070 6.084 86.0 9.6 20.3 2026 06 29 11 22.54 -04 28.7 6.244 6.085 76.4 9.3 20.3 2026 07 09 11 24.56 -03 36.6 6.411 6.086 67.0 8.8 20.4 2026 07 19 11 27.29 -02 53.1 6.569 6.089 57.8 8.1 20.4 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2026 CBAT 2026 April 22 (CBET 5682) Daniel W. E. Green