Electronic Telegram No. 5726 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 N2 On July 17, Madeleine K. McLeod reported to the Minor Planet Center the discovery of a comet on CCD images obtained on July 6 in the course of the "Legacy Survey of Space and Time" (LSST) with the 8.4-m f/1.2 Simonyi Survey Telescope of the Vera Rubin Observatory on Cerro Pachon in Chile. McLeod also found LSST images of the comet on July 9.23-9.26 UT and earlier on June 27.3; the discovery image showed a faint condensed coma with an extension to the northwest. On July 9, McLeod reported seeing a straight 2".0 tail in p.a. 300 deg with coma diameter 4".0. The first two LSST observations are tabulated below. 2026 UT R.A. (2000) Decl. Mag. June 27.32122 20 05 30.33 -21 10 19.9 22.4 July 6.28205 19 59 48.17 -21 37 58.0 21.9 R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports that he identified images of this LSST comet in exposures obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on June 21.5 (mag 22.3-23.5) and 25.5 UT (mag 21.1-22.8). Four 45-s w-band Pan-STARRS1 survey images taken in 1".3-1".5 seeing on July 15.4 show the comet at mag 21.6-21.8 with no obvious coma or tail; the head showed a size of 1".8 (full-width-at-half-maximum); Weryk discovered this object independently on July 15 before noticing that it was the LSST comet from the Minor Planet Center's PCCP webpage. Three stacked 60-s gri-band follow-up exposures taken by Weryk and Wainscoat with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea on July 18.3 (queue observer J. Nagasako; queue coordinator J. Ou) in 0".7-0".8 seeing show a very condensed head of size 1".2-1".3 (FWHM) with a broad-but-short tail 4" long spanning p.a. 280-350 degrees; the magnitude was measured to be 22.0-22.2. Weryk later identified observations of this comet on Pan-STARRS1 survey images taken on 2021 Aug. 4, 11, 12, 17, 18, and Oct. 3 (at mag 21.3-23.6), as well as on Pan-STARRS2 survey images taken on 2021 Sept. 9 (mag 21.7-22.4); the first such observations are tabulated below. 2021 UT R.A. (2000) Decl. Mag. Aug. 4.49384 23 55 16.38 - 3 49 19.8 22.4 4.49460 23 55 16.37 - 3 49 19.7 22.5 4.50583 23 55 16.29 - 3 49 20.7 23.4 4.50658 23 55 16.26 - 3 49 20.9 22.2 4.51784 23 55 16.17 - 3 49 22.3 21.6 4.51859 23 55 16.18 - 3 49 22.2 21.6 4.52985 23 55 16.13 - 3 49 24.0 22.8 4.53061 23 55 16.10 - 3 49 23.9 22.2 F. D. Romanov (Yuzhno-Morskoy, Nakhodka, Russia) writes that he remotely obtained seven stacked 60-s exposures with the 2-m f/10 Ritchey-Chretien Liverpool Telescope (+ Sloan r' filter) at La Palma on July 18.02 UT that show no coma or tail (magnitude 21.2). Twenty-eight stacked 60-s CCD exposures obtained remotely by H. Sato (Bunkyo-ku, Tokyo, Japan) on July 18.65-18.66 UT with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW, Australia, show only a stellar appearance; the magnitude was 21.5 as measured within a circular aperture of radius 3".2. The available astrometry appears on MPEC 2026-Q95. The following elliptical orbital elements by S. Nakano (Central Bureau) are from 80 observations spanning 2021 Aug. 4-2026 July 31 (mean residual 0".2). There were no close approaches to major planets found in the past. There are some possible identifications with objects in 2005. Epoch = 2005 Mar. 11.0 TT T = 2005 Mar. 10.91263 TT Peri. = 220.45076 e = 0.2073497 Node = 96.49533 2000.0 q = 2.4409937 AU Incl. = 2.24872 a = 3.0795342 AU n = 0.18237971 P = 5.40 years Epoch = 2010 July 23.0 TT T = 2010 Aug. 6.45105 TT Peri. = 220.64652 e = 0.2088669 Node = 96.48343 2000.0 q = 2.4351877 AU Incl. = 2.24877 a = 3.0781011 AU n = 0.18250710 P = 5.40 years Epoch = 2015 Dec. 4.0 TT T = 2015 Dec. 23.09126 TT Peri. = 219.75955 e = 0.2118873 Node = 96.41460 2000.0 q = 2.4226458 AU Incl. = 2.25024 a = 3.0739841 AU n = 0.18287387 P = 5.39 years Epoch = 2021 May 26.0 TT T = 2021 May 10.62915 TT Peri. = 219.37834 e = 0.2136411 Node = 96.40652 2000.0 q = 2.4179142 AU Incl. = 2.24999 a = 3.0748226 AU n = 0.18279907 P = 5.39 years Epoch = 2026 Oct. 7.0 TT T = 2026 Sept.25.77309 TT Peri. = 218.86533 e = 0.2121785 Node = 96.38130 2000.0 q = 2.4220689 AU Incl. = 2.24959 a = 3.0743879 AU n = 0.18283784 P = 5.39 years Epoch = 2032 Feb. 18.0 TT T = 2032 Feb. 10.97805 TT Peri. = 218.11927 e = 0.2113289 Node = 96.36697 2000.0 q = 2.4251413 AU Incl. = 2.24988 a = 3.0749718 AU n = 0.18278576 P = 5.39 years Epoch = 2037 July 1.0 TT T = 2037 July 5.00269 TT Peri. = 218.21025 e = 0.2096127 Node = 96.35261 2000.0 q = 2.4322619 AU Incl. = 2.24914 a = 3.0773037 AU n = 0.18257804 P = 5.40 years Epoch = 2042 Nov. 12.0 TT T = 2042 Nov. 28.08825 TT Peri. = 218.00416 e = 0.2048848 Node = 96.24635 2000.0 q = 2.4491050 AU Incl. = 2.24909 a = 3.0801889 AU n = 0.18232157 P = 5.41 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 17.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2026 07 19 19 49.86 -22 19.8 1.431 2.447 178.5 0.6 20.9 2026 07 29 19 41.84 -22 49.9 1.439 2.440 167.7 5.1 20.9 2026 08 08 19 34.91 -23 14.2 1.471 2.435 156.5 9.5 20.9 2026 08 18 19 30.02 -23 31.0 1.525 2.430 145.8 13.5 21.0 2026 08 28 19 27.83 -23 39.7 1.599 2.426 135.7 16.9 21.1 2026 09 07 19 28.58 -23 40.8 1.689 2.424 126.1 19.6 21.2 2026 09 17 19 32.24 -23 34.4 1.791 2.422 117.3 21.6 21.3 2026 09 27 19 38.60 -23 20.5 1.903 2.422 109.0 23.0 21.5 2026 10 07 19 47.33 -22 59.2 2.021 2.423 101.2 23.9 21.6 2026 10 17 19 58.11 -22 30.0 2.145 2.424 93.8 24.2 21.7 2026 10 27 20 10.57 -21 52.8 2.270 2.427 86.8 24.1 21.9 2026 11 06 20 24.40 -21 07.3 2.396 2.431 80.2 23.7 22.0 2026 11 16 20 39.32 -20 13.3 2.521 2.436 73.7 22.9 22.1 2026 11 26 20 55.08 -19 11.0 2.644 2.442 67.5 21.9 22.2 2026 12 06 21 11.47 -18 00.5 2.763 2.449 61.4 20.7 22.3 2026 12 16 21 28.32 -16 42.3 2.877 2.457 55.5 19.3 22.4 2026 12 26 21 45.48 -15 16.9 2.986 2.466 49.7 17.7 22.5 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 5726) Daniel W. E. Green