Electronic Telegram No. 5425 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/2007 HE_4 = P/1894 F1 (DENNING) M. Meyer (Limburg, Germany) reports his identification of the apparently asteroidal Mars-crosser 2007 HE_4, which was discovered by the LINEAR survey in observations from 2007 Apr. 17 (cf. MPS 207061, 208221, 210181), with the long-lost comet D/1894 F1 (Denning). Meyer notes that his attention was drawn to 2007 HE_4 via a post by P. VanWylen on the discussion group "comets-ml", in which VanWylen suggested that the orbit was cometary in nature. Meyer then used his own software to search his database of integrated orbits of comets for past and future epochs (and alternative integrated orbits for one-apparition objects), and found a good match for 2007 HE_4 with one of S. Nakano's predicted orbits for D/1894 F1. The LINEAR discovery observations are tabulated below. 2007 UT R.A. (2000) Decl. Mag. Apr. 17.12639 6 08 18.22 +27 00 24.6 18.7 17.13557 6 08 19.99 +27 00 24.2 18.9 17.14472 6 08 21.70 +27 00 23.5 19.5 Meyer notes that the comet likely was in outburst when Denning discovered the comet in 1894, when it passed about 0.4 AU from the earth. Meyer checked the observing logbooks for several large observatories but found no matching plates for the favorable 1963-1964 apparition, and he was unable to find other unnumbered minor planets that might be this comet, nor are there any unconfirmed comet reports from the nineteenth century that match this comet. In response to Meyer's posting of his linkage on the "comets-ml" discussion forum, P. Birtwhistle (Great Shefford, Berkshire, England) tells the Central Bureau that he obtained CCD images during twilight on three nights in 2007 with a 0.40-m Schmidt-Cassegrain reflector (cf. MPS 207061), which he has now analyzed carefully. The comet appears similarly slightly elongated on all three nights and with a head size that is up to 1.5 times that of nearby stars (full-width-at-half-maximum). On 2007 Apr. 18.9 UT, in 4".3-4".7 seeing, fifty-one 30-s exposures show a condensed coma with a diameter of 9", with an extension 11" long in p.a. 90 degrees. On Apr. 19.9, in 3".9-4".4 seeing, eighty-seven 30-s exposures show a condensed head of size 9", extended 9" in p.a. 85 deg. On Apr. 20.9, in 4".2-4".5 seeing, the measurements were difficult because the comet was close to field stars; forty-seven 30-s exposures show a condensed coma of diameter 6", extended 6" in p.a. 90 deg. In response to a query by the Central Bureau about images taken on 2007 Apr. 19.2 UT with the Dominion Astrophysical Observatory 1.82-m Plaskett telescope (cf. MPS 208221), D. Balam writes that he stacked thirteen 100-s exposures to find a coma diameter of 5".3 with a faint, spike-like tail extending 8".0 toward p.a. 92 degrees in 1".8 seeing. S. Deen (Simi Valley, CA, USA) writes that nothing is visible at the location of this comet on DECam images taken on 2017 Mar. 12 with the 4-m reflector at Cerro Tololo (limiting magnitude i = 23), and a search of other publicly available observations has yielded nothing. Deen notes that the apparitions between 1972 and 1997 had very poor observing geometry. Also in a response to a query from the Central Bureau, D. Rankin (Lunar and Planetary Laboratory, University of Arizona) writes that a single Catalina Sky Survey image from 2007 Apr. 18 showed the comet involved with stars and with poor signal-to-noise ratio; Rankin adds that no other opportunities were found in their survey observations during the years around that time. The following linked orbital elements by S. Nakano (Central Bureau) are from 257 observations spanning 1894 Mar. 27-2007 May 18 (weighting mean residual 0".8; mean residual 3".8), with non-gravitational parameters A1 = -0.49 +/- 0.09, A2 = +0.0257 +/- 0.0023. These indicate that the comet made thirteen unobserved revolutions in between 1894 and 2007. The comet passed 0.071 AU from Jupiter in July 1830, as well as the following distances from Jupiter since then: 0.63 AU on 1909 Jan. 14, 0.24 AU on 1925 June 18, 0.85 AU on 1949 Apr. 17, and 0.19 AU on 1986 Nov. 8. The comet passed 0.27 AU from the earth on 1894 Feb. 12, as well as 0.62 AU on 1908 Dec. 25, and 0.47 AU on 1964 Jan. 29. Nakano had predicted (cf. NK 782) T = 2007 Dec. 4 from 176 observations made in 1894. Epoch = 1894 Feb. 21.0 TT T = 1894 Feb. 9.94978 TT Peri. = 46.40037 e = 0.6985530 Node = 85.69353 2000.0 q = 1.1471967 AU Incl. = 5.52997 a = 3.8056332 AU n = 0.13275891 P = 7.42 years Epoch = 1901 Aug. 4.0 TT T = 1901 July 21.93769 TT Peri. = 46.49953 e = 0.6975468 Node = 85.60295 2000.0 q = 1.1537521 AU Incl. = 5.52137 a = 3.8146461 AU n = 0.13228868 P = 7.45 years Epoch = 1909 Jan. 14.0 TT T = 1908 Dec. 30.68204 TT Peri. = 46.70167 e = 0.6978363 Node = 85.50579 2000.0 q = 1.1507538 AU Incl. = 5.51290 a = 3.8083781 AU n = 0.13261541 P = 7.43 years Epoch = 1916 May 17.0 TT T = 1916 May 29.56668 TT Peri. = 48.53954 e = 0.7016705 Node = 84.21538 2000.0 q = 1.1256499 AU Incl. = 5.49577 a = 3.7731766 AU n = 0.13447557 P = 7.33 years Epoch = 1923 Sept.18.0 TT T = 1923 Sept.30.93416 TT Peri. = 48.66923 e = 0.7016750 Node = 84.10654 2000.0 q = 1.1257090 AU Incl. = 5.49091 a = 3.7734322 AU n = 0.13446190 P = 7.33 years Epoch = 1931 Sept.16.0 TT T = 1931 Sept.13.12916 TT Peri. = 81.14327 e = 0.6775153 Node = 55.48926 2000.0 q = 1.2898586 AU Incl. = 2.61328 a = 3.9997515 AU n = 0.12321244 P = 8.00 years Epoch = 1939 Sept.14.0 TT T = 1939 Sept.15.73643 TT Peri. = 81.39646 e = 0.6763410 Node = 55.37733 2000.0 q = 1.2959078 AU Incl. = 2.61406 a = 4.0039291 AU n = 0.12301966 P = 8.01 years Epoch = 1947 Sept.12.0 TT T = 1947 Sept.21.37619 TT Peri. = 81.53236 e = 0.6768341 Node = 55.23874 2000.0 q = 1.2929734 AU Incl. = 2.61249 a = 4.0009588 AU n = 0.12315667 P = 8.00 years Epoch = 1955 Nov. 29.0 TT T = 1955 Dec. 8.40992 TT Peri. = 86.36850 e = 0.6694311 Node = 51.79983 2000.0 q = 1.3477388 AU Incl. = 2.47889 a = 4.0770286 AU n = 0.11972599 P = 8.23 years Epoch = 1964 Feb. 15.0 TT T = 1964 Feb. 26.40131 TT Peri. = 87.48446 e = 0.6722324 Node = 51.23971 2000.0 q = 1.3265164 AU Incl. = 2.49335 a = 4.0471244 AU n = 0.12105542 P = 8.14 years Epoch = 1972 May 3.0 TT T = 1972 Apr. 23.67574 TT Peri. = 87.56533 e = 0.6717113 Node = 51.14820 2000.0 q = 1.3302366 AU Incl. = 2.49100 a = 4.0520324 AU n = 0.12083555 P = 8.16 years Epoch = 1980 June 10.0 TT T = 1980 June 20.90540 TT Peri. = 87.95577 e = 0.6720555 Node = 50.95721 2000.0 q = 1.3279097 AU Incl. = 2.48759 a = 4.0491906 AU n = 0.12096277 P = 8.15 years Epoch = 1988 July 18.0 TT T = 1988 July 26.96150 TT Peri. = 107.50223 e = 0.6469219 Node = 23.05205 2000.0 q = 1.5625530 AU Incl. = 4.00844 a = 4.4255170 AU n = 0.10586638 P = 9.31 years Epoch = 1997 Dec. 18.0 TT T = 1997 Dec. 5.77936 TT Peri. = 107.90371 e = 0.6443246 Node = 22.74203 2000.0 q = 1.5826429 AU Incl. = 4.00603 a = 4.4496830 AU n = 0.10500512 P = 9.39 years Epoch = 2007 Apr. 10.0 TT T = 2007 Apr. 22.44058 TT Peri. = 108.04001 e = 0.6449710 Node = 22.54844 2000.0 q = 1.5767009 AU Incl. = 4.00754 a = 4.4410482 AU n = 0.10531151 P = 9.36 years Epoch = 2016 Sept. 9.0 TT T = 2016 Sept. 2.03779 TT Peri. = 108.58716 e = 0.6451219 Node = 22.26157 2000.0 q = 1.5742786 AU Incl. = 4.00547 a = 4.4361102 AU n = 0.10548740 P = 9.34 years Epoch = 2025 Nov. 21.0 TT T = 2025 Dec. 4.04401 TT Peri. = 109.41739 e = 0.6471973 Node = 20.62484 2000.0 q = 1.5613394 AU Incl. = 4.02540 a = 4.4255309 AU n = 0.10586588 P = 9.31 years Epoch = 2035 Mar. 14.0 TT T = 2035 Mar. 27.49225 TT Peri. = 110.15098 e = 0.6483834 Node = 20.44934 2000.0 q = 1.5481233 AU Incl. = 4.04787 a = 4.4028736 AU n = 0.10668411 P = 9.24 years Epoch = 2044 July 4.0 TT T = 2044 July 2.76062 TT Peri. = 110.21969 e = 0.6472892 Node = 20.36057 2000.0 q = 1.5580421 AU Incl. = 4.04250 a = 4.4173362 AU n = 0.10616061 P = 9.28 years Epoch = 2053 Oct. 25.0 TT T = 2053 Oct. 5.20595 TT Peri. = 110.61172 e = 0.6494314 Node = 19.96482 2000.0 q = 1.5415829 AU Incl. = 4.05154 a = 4.3973785 AU n = 0.10688415 P = 9.22 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 15.0 and 2.5n = 10 for the magnitudes (from the 2007 observations). Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2024 07 29 00 48.74 +03 30.6 3.885 4.389 113.5 12.3 24.4 2024 08 18 00 46.25 +03 15.9 3.523 4.281 133.3 9.9 24.0 2024 09 07 00 37.86 +02 26.3 3.236 4.170 154.8 5.9 23.8 2024 09 27 00 24.78 +01 10.1 3.056 4.057 177.5 0.6 23.5 2024 10 17 00 10.29 -00 11.3 2.997 3.942 158.5 5.3 23.3 2024 11 06 23 58.66 -01 11.4 3.053 3.823 135.5 10.5 23.2 2024 11 26 23 53.12 -01 31.1 3.190 3.702 113.9 14.1 23.2 2024 12 16 23 54.81 -01 04.6 3.369 3.578 94.2 15.9 23.2 2025 01 05 00 03.31 +00 04.7 3.551 3.452 76.2 16.1 23.1 2025 01 25 00 17.57 +01 49.9 3.707 3.323 59.8 14.8 23.1 2025 02 14 00 36.51 +04 03.5 3.816 3.192 44.8 12.6 22.9 2025 07 24 05 11.85 +24 57.0 2.744 2.101 42.0 18.9 20.4 2025 08 03 05 37.17 +25 29.5 2.610 2.037 45.8 20.9 20.2 2025 08 13 06 03.55 +25 47.5 2.478 1.974 49.4 22.9 19.9 2025 08 23 06 30.95 +25 49.2 2.347 1.914 52.9 24.9 19.7 2025 09 02 06 59.22 +25 32.7 2.219 1.857 56.1 26.8 19.4 2025 09 12 07 28.22 +24 56.5 2.096 1.803 59.3 28.7 19.2 2025 09 22 07 57.76 +23 59.8 1.979 1.753 62.2 30.4 18.9 2025 10 02 08 27.61 +22 42.1 1.868 1.707 65.0 32.1 18.7 2025 10 12 08 57.51 +21 04.0 1.764 1.666 67.8 33.7 18.5 2025 10 22 09 27.21 +19 07.0 1.668 1.632 70.4 35.1 18.2 2025 11 01 09 56.43 +16 53.7 1.580 1.603 73.1 36.3 18.0 2025 11 11 10 24.92 +14 27.6 1.500 1.582 75.8 37.4 17.9 2025 11 21 10 52.44 +11 52.9 1.426 1.568 78.7 38.2 17.7 2025 12 01 11 18.70 +09 14.5 1.359 1.562 81.8 38.7 17.6 2025 12 11 11 43.48 +06 37.2 1.298 1.563 85.3 38.9 17.5 2025 12 21 12 06.46 +04 06.0 1.241 1.573 89.2 38.7 17.4 2025 12 31 12 27.32 +01 45.2 1.189 1.589 93.6 38.1 17.4 2026 01 10 12 45.69 -00 21.8 1.139 1.614 98.7 37.0 17.4 2026 01 20 13 01.14 -02 11.8 1.093 1.645 104.6 35.4 17.4 2026 01 30 13 13.20 -03 42.6 1.050 1.682 111.4 33.1 17.4 2026 02 09 13 21.47 -04 53.1 1.013 1.724 119.2 30.0 17.4 2026 02 19 13 25.58 -05 42.3 0.983 1.772 128.0 26.1 17.4 2026 03 01 13 25.47 -06 10.6 0.963 1.823 137.9 21.4 17.5 2026 03 11 13 21.52 -06 20.2 0.957 1.879 148.8 15.9 17.6 2026 03 21 13 14.61 -06 14.5 0.970 1.937 160.4 9.9 17.8 2026 03 31 13 06.14 -05 59.7 1.004 1.998 172.3 3.8 18.0 2026 04 10 12 57.69 -05 42.8 1.061 2.062 175.7 2.1 18.3 2026 04 20 12 50.60 -05 30.2 1.142 2.126 164.2 7.4 18.6 2026 04 30 12 45.79 -05 26.9 1.246 2.193 153.3 11.9 18.9 2026 05 10 12 43.62 -05 35.1 1.369 2.260 143.2 15.5 19.2 2026 05 20 12 44.05 -05 55.2 1.511 2.328 133.8 18.3 19.6 2026 05 30 12 46.87 -06 26.6 1.667 2.397 125.0 20.3 19.9 2026 06 09 12 51.73 -07 07.4 1.836 2.466 116.8 21.5 20.2 2026 06 19 12 58.29 -07 56.2 2.015 2.536 109.1 22.3 20.6 2026 06 29 13 06.27 -08 51.4 2.201 2.605 101.7 22.5 20.9 2026 07 09 13 15.39 -09 51.4 2.392 2.674 94.7 22.3 21.2 2026 07 19 13 25.44 -10 54.8 2.588 2.743 87.8 21.7 21.4 2026 07 29 13 36.27 -12 00.6 2.784 2.812 81.1 20.9 21.7 2026 08 08 13 47.73 -13 07.5 2.980 2.881 74.6 19.8 22.0 2026 08 18 13 59.71 -14 14.8 3.173 2.949 68.1 18.6 22.2 2026 08 28 14 12.13 -15 21.7 3.362 3.017 61.7 17.1 22.4 2026 09 07 14 24.91 -16 27.3 3.545 3.084 55.3 15.6 22.6 2026 09 17 14 38.00 -17 31.1 3.720 3.151 48.8 13.9 22.8 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2024 CBAT 2024 August 2 (CBET 5425) Daniel W. E. Green