Electronic Telegram No. 5543 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/2009 KF_37 In Oct. 2012, A. Waszczak (California Institute of Technology) and E. O. Ofek (Weizmann Institute of Science) reported that they found slight cometary appearance in archived CCD images of minor planet 2009 KF_37 (cf. MPS 434191), which had been found in images obtained on 2009 Mar. 25 and 27 with the 1.2-m f/2.4 Oschin Schmidt telescope during the Palomar Transient Factory (PTF) survey (cf. Law et al. 2009, PASP 121, 1395; Rau et al. 2009, PASP 121, 1334). The object showed a head of size 5".2 (+/- 1".5) full-width-at-half-maximum in 2".4 (+/- 0".5) seeing with no tail visible in the 60-s exposures (resolution 1".0/pixel). The discovery observations are tabulated below. 2009 UT R.A. (2000) Decl. Mag. May 25.27712 15 24 09.48 - 2 03 28.3 20.5 25.33239 15 24 07.21 - 2 03 32.1 20.4 25.38302 15 24 05.12 - 2 03 35.2 20.4 25.41055 15 24 03.99 - 2 03 36.9 20.4 25.42766 15 24 03.26 - 2 03 38.3 20.5 25.44023 15 24 02.76 - 2 03 39.4 20.2 25.44971 15 24 02.35 - 2 03 39.9 20.6 25.45775 15 24 02.08 - 2 03 40.0 20.4 27.20469 15 22 54.38 - 2 05 56.3 19.6 27.28282 15 22 51.25 - 2 06 04.0 19.3 27.33493 15 22 49.17 - 2 06 07.3 19.6 27.37092 15 22 47.68 - 2 06 10.7 19.5 27.39923 15 22 46.57 - 2 06 13.4 19.7 27.42913 15 22 45.40 - 2 06 15.8 19.6 27.43979 15 22 44.96 - 2 06 16.5 19.8 27.44885 15 22 44.57 - 2 06 17.4 19.8 R. Weryk, Department of Physics and Astronomy, University of Western Ontario, reports finding cometary activity in 2009 KF_37 in images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on 2017 Apr. 26 UT, when four stacked 45-s w-band survey exposures showed a condensed coma of size 1".7 (FWHM) in 1".3 seeing with no obvious tail. Four stacked 45-s w-band Pan-STARRS1 exposures taken on 2017 Apr. 28 in 1".5 seeing show a condensed head of size 1".7 (FWHM) with no obvious tail. Four stacked 45-s w-band Pan-STARRS1 exposures taken on 2017 May 18 in 1".3 seeing show a condensed head of size 1".6 (FWHM) with no obvious tail. CCD images obtained remotely on 2017 Apr. 28.6 UT by H. Sato (Bunkyo-ku, Tokyo, Japan) with a 0.70-m f/6.6 astrograph show only a stellar appearance; the total w-band magnitude was 20.9 as measured within a circular aperture of radius 3".3. Apparently asteroidal CCD images of 2009 KF_37 obtained in 2001 on two nights by B. A. Skiff and T. R. Grimstad with the 0.59-m LONEOS Schmidt telescope of Lowell Observatory were subsequently identified, as tabulated below. 2001 UT R.A. (2000) Decl. Mag. May 23.19387 14 00 28.14 + 5 01 33.4 19.0 23.22507 14 00 27.33 + 5 01 29.3 23.25637 14 00 26.46 + 5 01 26.0 23.27977 14 00 25.91 + 5 01 22.9 June 18.17411 13 56 27.23 + 3 06 23.0 18.5 18.19047 13 56 27.42 + 3 06 15.4 18.20682 13 56 27.39 + 3 06 10.2 18.22322 13 56 27.52 + 3 06 02.4 The available astrometry, including from astrometry obtained with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala on 2025 Mar. 26.4 UT (at w-band mag 22.1-22.5), appear on MPEC 2025-H87. The following linked orbital elements by S. Nakano (Central Bureau) are from 78 observations spanning 2001 May 23-2025 Mar. 26 (mean residual 0".7). The comet passed 0.95 AU from Jupiter on 2012 Jan. 15 UT. Epoch = 2001 Oct. 18.0 TT T = 2001 Oct. 7.87725 TT Peri. = 136.52961 e = 0.3411145 Node = 118.44440 2000.0 q = 2.6012842 AU Incl. = 11.20646 a = 3.9480062 AU n = 0.12564272 P = 7.84 years Epoch = 2009 July 28.0 TT T = 2009 Aug. 9.13990 TT Peri. = 136.66010 e = 0.3422535 Node = 118.39447 2000.0 q = 2.5901301 AU Incl. = 11.21636 a = 3.9378849 AU n = 0.12612743 P = 7.81 years Epoch = 2017 Oct. 14.0 TT T = 2017 Sept.26.40015 TT Peri. = 144.02101 e = 0.3127898 Node = 111.95066 2000.0 q = 2.8160651 AU Incl. = 11.39995 a = 4.0978221 AU n = 0.11881586 P = 8.30 years Epoch = 2025 Dec. 31.0 TT T = 2026 Jan. 17.63825 TT Peri. = 143.94885 e = 0.3107490 Node = 111.94172 2000.0 q = 2.8351086 AU Incl. = 11.38827 a = 4.1133184 AU n = 0.11814506 P = 8.34 years Epoch = 2034 June 7.0 TT T = 2034 May 25.19402 TT Peri. = 144.35666 e = 0.3122195 Node = 111.82613 2000.0 q = 2.8224497 AU Incl. = 11.40239 a = 4.1037071 AU n = 0.11856037 P = 8.31 years Epoch = 2042 Oct. 3.0 TT T = 2042 Sept.14.00513 TT Peri. = 143.97266 e = 0.3108155 Node = 111.67766 2000.0 q = 2.8382065 AU Incl. = 11.40086 a = 4.1182101 AU n = 0.11793462 P = 8.36 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 14.0 and 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2025 03 26 13 20.15 +08 50.4 2.306 3.266 161.3 5.6 19.9 2025 04 05 13 14.05 +09 43.0 2.269 3.242 163.7 5.0 19.9 2025 04 15 13 07.56 +10 24.4 2.261 3.217 159.0 6.4 19.8 2025 04 25 13 01.38 +10 50.6 2.278 3.194 150.7 8.9 19.8 2025 05 05 12 56.16 +10 59.1 2.320 3.170 141.3 11.5 19.8 2025 05 15 12 52.42 +10 49.2 2.382 3.147 131.8 13.9 19.9 2025 05 25 12 50.44 +10 22.2 2.462 3.125 122.5 15.9 19.9 2025 06 04 12 50.40 +09 39.7 2.554 3.103 113.7 17.4 20.0 2025 06 14 12 52.29 +08 43.9 2.655 3.082 105.3 18.5 20.0 2025 06 24 12 56.00 +07 37.2 2.762 3.062 97.3 19.2 20.1 2025 07 04 13 01.40 +06 21.5 2.873 3.042 89.7 19.5 20.2 2025 07 14 13 08.33 +04 58.8 2.983 3.023 82.5 19.5 20.2 2025 07 24 13 16.63 +03 30.7 3.092 3.005 75.6 19.1 20.3 2025 08 03 13 26.14 +01 58.5 3.198 2.987 68.9 18.5 20.3 2025 08 13 13 36.74 +00 23.5 3.299 2.970 62.5 17.6 20.4 2025 08 23 13 48.32 -01 13.1 3.393 2.954 56.3 16.5 20.4 2025 09 02 14 00.78 -02 50.2 3.481 2.939 50.2 15.3 20.5 2026 02 09 18 24.17 -18 33.8 3.459 2.838 44.3 14.1 20.3 2026 02 19 18 40.45 -18 33.1 3.365 2.841 50.5 15.6 20.3 2026 03 01 18 56.04 -18 27.3 3.264 2.845 56.8 16.9 20.2 2026 03 11 19 10.79 -18 17.8 3.155 2.851 63.3 18.1 20.1 2026 03 21 19 24.57 -18 05.8 3.041 2.857 70.0 19.1 20.1 2026 03 31 19 37.22 -17 53.1 2.922 2.865 76.8 19.8 20.0 2026 04 10 19 48.58 -17 41.5 2.800 2.873 84.0 20.3 19.9 2026 04 20 19 58.48 -17 32.8 2.678 2.883 91.4 20.4 19.8 2026 04 30 20 06.72 -17 29.2 2.557 2.894 99.2 20.1 19.7 2026 05 10 20 13.13 -17 32.5 2.439 2.906 107.4 19.4 19.6 2026 05 20 20 17.51 -17 44.6 2.328 2.918 116.1 18.1 19.6 2026 05 30 20 19.71 -18 06.8 2.227 2.932 125.3 16.4 19.5 2026 06 09 20 19.66 -18 39.7 2.140 2.946 135.0 14.1 19.4 2026 06 19 20 17.38 -19 22.9 2.070 2.962 145.2 11.3 19.4 2026 06 29 20 13.10 -20 14.6 2.021 2.978 155.9 8.0 19.3 2026 07 09 20 07.27 -21 11.6 1.996 2.995 167.0 4.4 19.3 2026 07 19 20 00.53 -22 09.9 1.998 3.013 177.7 0.8 19.3 2026 07 29 19 53.69 -23 05.3 2.027 3.032 170.2 3.3 19.4 2026 08 08 19 47.56 -23 54.3 2.082 3.051 159.2 6.8 19.5 2026 08 18 19 42.84 -24 34.8 2.163 3.072 148.4 9.9 19.6 2026 08 28 19 40.04 -25 05.9 2.266 3.092 138.1 12.6 19.7 2026 09 07 19 39.40 -25 27.6 2.388 3.114 128.2 14.7 19.8 2026 09 17 19 40.99 -25 40.5 2.525 3.136 118.8 16.3 20.0 2026 09 27 19 44.73 -25 45.0 2.673 3.158 109.9 17.4 20.1 2026 10 07 19 50.41 -25 41.9 2.830 3.181 101.4 17.9 20.3 2026 10 17 19 57.81 -25 31.6 2.992 3.205 93.2 18.1 20.4 2026 10 27 20 06.70 -25 14.4 3.155 3.229 85.3 17.9 20.6 2026 11 06 20 16.81 -24 50.7 3.318 3.254 77.6 17.3 20.7 2026 11 16 20 27.94 -24 20.7 3.478 3.278 70.2 16.5 20.8 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 April 26 (CBET 5543) Daniel W. E. Green