Electronic Telegram No. 5705 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 L2 (PANSTARRS) R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports the discovery of another comet in images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala (discovery observations tabulated below); eight 45-s stacked w-band survey images taken in 1".2-1".3 seeing show a diffuse coma of size 2".1 (full-width-at-half- maximum) with a straight 12"-long tail toward p.a. 210 degrees. 2026 UT R.A. (2000) Decl. Mag. June 12.56143 20 08 38.85 - 4 42 30.9 20.8 12.56208 20 08 38.82 - 4 42 30.5 20.4 12.57004 20 08 38.50 - 4 42 23.4 20.7 12.57069 20 08 38.48 - 4 42 22.4 20.4 12.57845 20 08 38.15 - 4 42 15.7 20.4 12.57911 20 08 38.13 - 4 42 15.2 20.5 12.58751 20 08 37.77 - 4 42 07.5 20.4 Weryk was able to identify pre-discovery images of the comet on several nights. Three 45-s stacked w-band survey images taken on May 14.5 UT with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala in 1".3-1".4 seeing show a diffuse head of size 1".9 (FWHM) with a tail 10" long in p.a. 220 degrees. Two stacked 45-s Pan-STARRS1 w-band survey images taken on May 21.6 show a diffuse head of size about 2".8 (FWHM) and a 4" tail in p.a. 210 degrees. Three 45-s Pan-STARRS1 w-band survey images taken in oor conditions (seeing 2".4-2".6) on June 9.52-9.56 show a 4" tail in p.a. 220 degrees. Three 60-s stacked gri-band follow-up images obtained on June 13.5 by Weryk and Wainscoat with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea (queue observer J. Nagasako; queue coordinator H. Flewelling) in 1".0 seeing show a condensed head of size 1".6 (FWHM) and a broad 18"-long tail spanning p.a. 195-215 degrees. The available astrometry appears on MPEC 2026-L104. The following parabolic orbital elements by S. Nakano (Central Bureau) are from 20 observations spanning 2026 May 14-June 14 (mean residual 0".2). There are no close approaches to major planets. T = 2026 Apr. 10.10472 TT Peri. = 0.06198 Node = 283.67489 2000.0 q = 3.4001030 AU Incl. = 55.55954 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 13.5 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2026 06 09 20 10.94 -05 36.5 2.678 3.446 132.5 12.5 19.9 2026 06 19 20 03.94 -03 06.1 2.608 3.462 141.5 10.5 19.9 2026 06 29 19 55.40 -00 42.3 2.567 3.480 149.4 8.5 19.9 2026 07 09 19 45.87 +01 30.2 2.556 3.501 154.6 7.1 19.9 2026 07 19 19 36.00 +03 27.0 2.576 3.525 155.3 6.9 19.9 2026 07 29 19 26.54 +05 05.1 2.627 3.550 151.2 7.9 20.0 2026 08 08 19 18.12 +06 23.8 2.706 3.578 144.1 9.6 20.1 2026 08 18 19 11.25 +07 24.0 2.811 3.607 135.9 11.3 20.2 2026 08 28 19 06.27 +08 08.6 2.936 3.639 127.4 12.7 20.3 2026 09 07 19 03.31 +08 40.9 3.079 3.673 118.9 13.9 20.5 2026 09 17 19 02.36 +09 04.6 3.233 3.708 110.6 14.7 20.6 2026 09 27 19 03.32 +09 23.2 3.396 3.746 102.6 15.1 20.7 2026 10 07 19 06.03 +09 39.7 3.564 3.785 95.0 15.3 20.9 2026 10 17 19 10.29 +09 56.7 3.733 3.825 87.7 15.1 21.0 2026 10 27 19 15.91 +10 16.2 3.901 3.868 80.7 14.7 21.2 2026 11 06 19 22.69 +10 40.0 4.065 3.911 74.1 14.1 21.3 2026 11 16 19 30.45 +11 09.2 4.224 3.956 67.7 13.4 21.4 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2026 CBAT 2026 June 15 (CBET 5705) Daniel W. E. Green