Electronic Telegram No. 5529 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/2016 P5 (COIAS) S. Urakawa, Japan Spaceguard Association, JAXA Bisei Spaceguard Center, Okayama, and the leader of the Japanese citizen-science "Small Solar System Bodies Search Project" (COIAS), reports the discovery by H. Fukuyama of a comet on images acquired with the Subaru 8.2-m telescope at Mauna Kea. The object was first reported to the Minor Planet Center with 2016 Aug. 1 observations (which did not show cometary appearance), but Fukuyama noticed cometary activity on Subaru images obtained on 2016 July 3 and 7 (and reported by Fukuyama on 2025 Mar. 16). On 2016 July 3, the comet had a condensed head of size 1".3 with a broad 5".9-long tail spanning p.a. 223-244 degrees (r-band magnitude gien as 24.4). On 2016 July 7, the condensed head had a size of 1".0 (magnitude g = 24.7) and a broad 3".0-long tail spanning p.a. 214-253 degrees. Subaru images obtained on 2017 July 29 show a condensed 1".0 head (mag z = 23.7) with a broad 4".3-long tail spanning p.a. 219-246 degrees. Subaru images taken on 2016 Aug. 9 also show no coma and no tail. 2016 UT R.A. (2000) Decl. Mag. Aug. 1.48689 23 32 39.17 + 0 11 32.1 24.1 1.51940 23 32 38.70 + 0 11 28.2 24.2 1.54382 23 32 38.30 + 0 11 25.9 24.0 1.56550 23 32 37.97 + 0 11 23.3 24.3 1.59001 23 32 37.63 + 0 11 20.6 24.4 S. Deen (Simi Valley, CA, USA) writes that he identified observations of this comet (with none showing obvious cometary activity) in publicly available archive data going back to 2004 June 23.09 UT (when CCD images taken with the 2.5-m Isaac Newton Telescope at La Palma showed magnitudes r = 23.4 and i = 23.2). A single Subaru image from 2012 July 22.26 yielded magnitude V = 24.2. A single r-band image taken with the 2.65-m VLT Survey Telescope at Paranal, Chile, on 2013 July 28.04 yields mag 21.9. Deen also identified single r-band images of this comet taken with the 4-m reflector (+ DECam) at Cerro Tololo on 2023 Apr. 17.32 (mag 22.6) and 2023 Apr. 23.29 (mag 22.5). The available astrometry appears on MPEC 2025-F40. The following linked orbital elements by S. Nakano (Central Bureau) are from 58 observations spanning 2004 June 23-2023 Apr. 23 (mean residual 0".4). The comet passed 0.89 AU from Jupiter on 1988 Sept. 6 UT. Epoch = 2003 Jan. 1.0 TT T = 2003 Jan. 13.48179 TT Peri. = 33.64168 e = 0.0584212 Node = 185.59958 2000.0 q = 4.3963984 AU Incl. = 7.04556 a = 4.6691775 AU n = 0.09768851 P = 10.09 years Epoch = 2013 Mar. 9.0 TT T = 2013 Mar. 2.08118 TT Peri. = 33.49216 e = 0.0578391 Node = 185.52965 2000.0 q = 4.4265430 AU Incl. = 7.03701 a = 4.6982876 AU n = 0.09678202 P = 10.18 years Epoch = 2023 May 16.0 TT T = 2023 May 29.75851 TT Peri. = 34.67352 e = 0.0574054 Node = 185.40489 2000.0 q = 4.4332547 AU Incl. = 7.03830 a = 4.7032466 AU n = 0.09662899 P = 10.20 years Epoch = 2033 Aug. 31.0 TT T = 2033 Aug. 18.13313 TT Peri. = 36.30633 e = 0.0582049 Node = 185.31809 2000.0 q = 4.4079831 AU Incl. = 7.04881 a = 4.6804058 AU n = 0.09733719 P = 10.13 years Epoch = 2043 Aug. 19.0 TT T = 2043 Sept. 1.68676 TT Peri. = 35.01720 e = 0.0601779 Node = 185.32196 2000.0 q = 4.3796496 AU Incl. = 7.05554 a = 4.6600836 AU n = 0.09797460 P = 10.06 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 13.5 and 2.5n = 7.5 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2025 03 26 20 10.85 -13 35.4 4.958 4.600 63.5 11.2 21.9 2025 04 05 20 17.62 -13 03.6 4.822 4.605 71.6 11.9 21.9 2025 04 15 20 23.39 -12 33.2 4.679 4.609 79.9 12.4 21.8 2025 04 25 20 28.07 -12 05.0 4.532 4.613 88.3 12.6 21.8 2025 05 05 20 31.55 -11 40.1 4.384 4.618 97.1 12.5 21.7 2025 05 15 20 33.74 -11 19.4 4.240 4.622 106.0 12.1 21.6 2025 05 25 20 34.58 -11 03.8 4.102 4.627 115.3 11.4 21.6 2025 06 04 20 34.02 -10 54.1 3.976 4.631 124.9 10.4 21.5 2025 06 14 20 32.12 -10 50.7 3.865 4.636 134.7 9.0 21.4 2025 06 24 20 28.96 -10 54.0 3.773 4.640 144.8 7.3 21.4 2025 07 04 20 24.72 -11 03.7 3.704 4.645 154.9 5.3 21.3 2025 07 14 20 19.71 -11 19.3 3.661 4.649 164.7 3.3 21.3 2025 07 24 20 14.25 -11 39.7 3.646 4.654 171.7 1.8 21.3 2025 08 03 20 08.77 -12 03.5 3.660 4.658 168.2 2.6 21.3 2025 08 13 20 03.68 -12 29.2 3.703 4.663 158.8 4.5 21.4 2025 08 23 19 59.36 -12 55.3 3.774 4.667 148.7 6.5 21.4 2025 09 02 19 56.11 -13 20.3 3.868 4.672 138.5 8.2 21.5 2025 09 12 19 54.16 -13 43.0 3.984 4.676 128.4 9.7 21.5 2025 09 22 19 53.60 -14 02.5 4.117 4.681 118.6 10.9 21.6 2025 10 02 19 54.49 -14 18.2 4.263 4.685 109.0 11.7 21.7 2025 10 12 19 56.77 -14 29.4 4.417 4.690 99.7 12.1 21.8 2025 10 22 20 00.38 -14 35.9 4.576 4.695 90.7 12.2 21.8 2025 11 01 20 05.19 -14 37.3 4.735 4.699 81.9 12.1 21.9 2025 11 11 20 11.08 -14 33.7 4.891 4.704 73.3 11.6 22.0 2025 11 21 20 17.91 -14 24.9 5.041 4.708 64.9 11.0 22.1 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2025 CBAT 2025 March 21 (CBET 5529) Daniel W. E. Green