Electronic Telegram No. 5427 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/2024 N6 = P/2002 QU_151 (NEAT-PANSTARRS) [Editor's note: this text replaces that on CBET 5426 (2002 information).] 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 (discovery observations tabulated below). 2024 UT R.A. (2000) Decl. Mag. July 9.58965 1 35 51.69 +16 27 27.2 20.6 9.59435 1 35 52.18 +16 27 32.4 20.5 9.60374 1 35 53.18 +16 27 43.0 20.4 Weryk arranged for three 40-s gri-band images to be taken (with R. Wainscoat) at the 3.6-m Canada-France-Hawaii Telescope atop Mauna Kea on 2024 Sept. 11.6 UT (queue observer L. Wells; queue coordinator V. Khatu), which show this object to be clearly cometary in 1".0 seeing, with a condensed head of size 1".5 (full-width-at-half-maximum) and a straight tail 8" long toward p.a. 230 degrees (at which point Weryk moved the comet from the Minor Planet Center's NEOCP webpage to its PCCP webpage). Three additional 30-s gri-band CFHT images obtained on July 13.58 (queue observer J. Silva; queue coordinator H. Flewelling) in 2".0 seeing show a condensed head of size 2".3 and a straight 8" tail in p.a. 230 deg. On 2012 July 5, Reinder J. Bouma (Groningen, The Netherlands) reported to both the MPC and the CBAT his finding a possible comet in public archive images obtained in mid-2002 by the NEAT survey with the 1.2-m Schmidt telescope at Palomar (but never reported by the NEAT survey, apparently). Bouma reported then that it appeared "(nearly) stellar on most images, but appears to be softer than stars of similar brightness on Aug. 18, 29, and Sept. 2." He added that the stacked Aug. 29 image looks slightly diffuse, with a size of 3".5 (FWHM) in 2".5 seeing. The borderline evidence on cometary appearance led G. V. Williams at the MPC to then assign the minor-planet designation 2002 QU_151 on MPS 428166 (dated 2012 July 16); the NEAT program ended in 2007. The 2002 discovery observations are tabulated below; there was a 2-month arc of observations in 2002. Weryk suggested the identification of C/2024 N6 with 2002 QU_151. 2002 UT R.A. (2000) Decl. Mag. July 6.46470 20 51 31.90 -30 41 23.0 20.4 6.47516 20 51 31.72 -30 41 18.1 20.6 6.48564 20 51 31.52 -30 41 14.7 19.7 16.36907 20 48 20.94 -29 28 46.0 20.1 16.39347 20 48 20.09 -29 28 34.5 19.2 16.41959 20 48 19.24 -29 28 20.9 19.4 Aug. 18.18108 20 29 17.28 -22 50 14.2 19.0 18.20190 20 29 16.68 -22 49 55.9 18.8 18.22270 20 29 16.14 -22 49 37.3 19.3 29.21512 20 27 05.61 -20 01 27.5 19.0 29.23632 20 27 05.53 -20 01 07.7 19.0 29.25767 20 27 05.45 -20 00 48.1 19.6 H. Sato (Bunkyo-ku, Tokyo, Japan) writes that ten stacked 60-s CCD exposures taken remotely on 2024 July 18.4 UT with a "Deep Sky Chile" 0.51-m f/6.8 astrograph located at Rio Hurtado, Chile, show only a stellar appearance; the PCCP P21WnsB appeared stellard on 10-stacked images of 60-sec exposure. magnitude was 21.0 as measured within a circular aperture of radius 2".2. S. Deen (Simi Valley, CA, USA) relates that he found archival images of this comet in DECam images taken with the 4-m Cerro Tololo reflector on two nights in April of this year. on 2024 Apr. 18.4, there appears to be a coma of size 1".5 (FWHM) in 0".6 seeing and possibly a faint 2".5 tail in p.a. 250 degrees (magnitude r = 21.8-22.3). On Apr. 19.4, there is a coma of size 1".2 (FWHM) in 0".7 seeing but no clear tail. The available astrometry appears on MPEC 2024-P41. The following linked orbital elements by S. Nakano (Central Bureau) are from 66 observations spanning 2002 July 6-2024 Aug. 2 (mean residual 0".4). The comet passed 0.38 AU from Jupiter on 1991 June 3 UT, and it will pass 0.71 AU from Jupiter on 2026 June 27 and 0.55 AU from Jupiter on 2051 Jan. 7 UT. Epoch = 1995 June 12.0 TT T = 1995 June 3.35428 TT Peri. = 1.16670 e = 0.5484207 Node = 324.22168 2000.0 q = 1.6892906 AU Incl. = 11.36163 a = 3.7408505 AU n = 0.13622240 P = 7.24 years Epoch = 2002 Sept. 3.0 TT T = 2002 Sept. 3.92009 TT Peri. = 1.25292 e = 0.5471001 Node = 324.16139 2000.0 q = 1.6985286 AU Incl. = 11.34129 a = 3.7503402 AU n = 0.13570570 P = 7.26 years Epoch = 2009 Nov. 25.0 TT T = 2009 Dec. 3.57038 TT Peri. = 1.26578 e = 0.5487151 Node = 324.15829 2000.0 q = 1.6900048 AU Incl. = 11.36186 a = 3.7448732 AU n = 0.13600297 P = 7.25 years Epoch = 2017 Feb. 16.0 TT T = 2017 Feb. 25.12006 TT Peri. = 1.29960 e = 0.5495924 Node = 324.15045 2000.0 q = 1.6834277 AU Incl. = 11.35621 a = 3.7375655 AU n = 0.13640204 P = 7.23 years Epoch = 2024 May 10.0 TT T = 2024 May 19.15645 TT Peri. = 1.44687 e = 0.5504216 Node = 324.07491 2000.0 q = 1.6777942 AU Incl. = 11.36468 a = 3.7319278 AU n = 0.13671124 P = 7.21 years Epoch = 2031 Nov. 30.0 TT T = 2031 Dec. 2.27973 TT Peri. = 5.86698 e = 0.5224243 Node = 321.81561 2000.0 q = 1.8513430 AU Incl. = 11.83611 a = 3.8765431 AU n = 0.12913297 P = 7.63 years Epoch = 2039 July 31.0 TT T = 2039 July 28.60105 TT Peri. = 5.97995 e = 0.5216783 Node = 321.77774 2000.0 q = 1.8600198 AU Incl. = 11.81924 a = 3.8886377 AU n = 0.12853099 P = 7.67 years Epoch = 2047 Mar. 31.0 TT T = 2047 Mar. 23.62556 TT Peri. = 6.04588 e = 0.5231779 Node = 321.73672 2000.0 q = 1.8482451 AU Incl. = 11.83833 a = 3.8761737 AU n = 0.12915143 P = 7.63 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 16.0 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 07 29 02 07.57 +21 59.7 1.524 1.814 88.8 34.0 19.5 2024 08 03 02 14.59 +23 18.2 1.498 1.832 91.6 33.6 19.5 2024 08 08 02 21.04 +24 33.6 1.472 1.852 94.5 33.1 19.5 2024 08 13 02 26.85 +25 45.9 1.447 1.872 97.5 32.4 19.5 2024 08 18 02 31.98 +26 54.9 1.422 1.893 100.8 31.7 19.5 2024 08 23 02 36.35 +28 00.5 1.397 1.915 104.2 30.8 19.5 2024 08 28 02 39.92 +29 02.4 1.374 1.938 107.8 29.8 19.6 2024 09 02 02 42.59 +30 00.5 1.351 1.961 111.6 28.6 19.6 2024 09 07 02 44.33 +30 54.2 1.330 1.985 115.5 27.3 19.6 2024 09 12 02 45.09 +31 43.2 1.311 2.010 119.7 25.8 19.6 2024 09 17 02 44.85 +32 26.9 1.294 2.035 124.0 24.2 19.6 2024 09 22 02 43.61 +33 04.8 1.280 2.060 128.5 22.4 19.7 2024 09 27 02 41.40 +33 36.0 1.269 2.086 133.1 20.5 19.7 2024 10 02 02 38.26 +34 00.0 1.261 2.113 137.8 18.5 19.8 2024 10 07 02 34.31 +34 16.1 1.258 2.140 142.6 16.5 19.8 2024 10 12 02 29.71 +34 23.9 1.259 2.167 147.3 14.4 19.9 2024 10 17 02 24.63 +34 23.4 1.265 2.194 151.7 12.4 19.9 2024 10 22 02 19.28 +34 14.6 1.277 2.222 155.6 10.7 20.0 2024 10 27 02 13.88 +33 58.2 1.295 2.250 158.7 9.2 20.1 2024 11 01 02 08.63 +33 35.0 1.319 2.278 160.5 8.4 20.2 2024 11 06 02 03.74 +33 06.1 1.348 2.307 160.5 8.3 20.3 2024 11 11 01 59.37 +32 33.1 1.385 2.335 158.8 8.8 20.4 2024 11 16 01 55.67 +31 57.4 1.427 2.364 155.8 9.9 20.5 2024 11 21 01 52.69 +31 20.6 1.475 2.393 152.0 11.2 20.6 2024 11 26 01 50.49 +30 43.7 1.529 2.422 147.8 12.5 20.8 2024 12 06 01 48.49 +29 34.4 1.653 2.480 138.7 15.2 21.0 2024 12 16 01 49.57 +28 36.2 1.796 2.539 129.6 17.4 21.3 2024 12 26 01 53.37 +27 51.9 1.954 2.598 120.7 19.0 21.6 2025 01 05 01 59.49 +27 22.1 2.125 2.656 112.1 20.1 21.9 2025 01 15 02 07.55 +27 05.9 2.305 2.715 103.9 20.6 22.2 2025 01 25 02 17.18 +27 01.4 2.492 2.773 96.0 20.7 22.4 2025 02 04 02 28.09 +27 06.6 2.682 2.832 88.4 20.4 22.7 2025 02 14 02 40.06 +27 19.4 2.873 2.890 81.1 19.7 22.9 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 August 4 (CBET 5427) Daniel W. E. Green