Electronic Telegram No. 4094 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; 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/2015 HC_10 = P/2004 R1 (McNAUGHT) G. V. Williams, F. Manca, and P. Sicoli have each identified an apparently asteroidal object found on images taken with the Cerro Tololo 4-m reflector (+ DECam) by L. Allen and D. James (measured by F. Valdes), which was posted on the Minor Planet Center's NEOCP webpage and then announced on MPEC 2015-H82 with the minor-planet designation 2015 HC_10, with comet P/2004 R1 (cf. IAUCs 8398, 8400). Additional observations were also obtained with the Spacewatch 1.8-m f/2.7 reflector by T. H. Bressi. 2015 UT R.A. (2000) Decl. Mag. Observer Apr. 18.98923 12 34 10.77 -16 02 41.1 22.4 Allen 18.99246 12 34 10.44 -16 02 39.7 " 18.99562 12 34 10.13 -16 02 38.5 " 18.99877 12 34 09.80 -16 02 37.1 " 19.99406 12 32 31.12 -15 55 24.7 22.2 " 19.99742 12 32 30.79 -15 55 23.2 " 20.00091 12 32 30.42 -15 55 21.8 " 20.00435 12 32 30.08 -15 55 20.3 " 20.22641 12 32 07.59 -15 53 54.1 21.8 Bressi 20.23352 12 32 06.87 -15 53 50.7 21.8 " 20.24063 12 32 06.12 -15 53 47.7 21.8 " 20.98853 12 30 52.37 -15 47 57.6 22.4 Allen 20.99170 12 30 52.04 -15 47 56.2 " 20.99492 12 30 51.72 -15 47 54.9 " 20.99810 12 30 51.41 -15 47 53.4 " 21.00127 12 30 51.10 -15 47 52.0 " 21.14904 12 30 36.26 -15 46 56.5 21.7 Bressi 21.16270 12 30 34.74 -15 46 50.4 " 21.17639 12 30 33.37 -15 46 43.8 " 21.98907 12 29 12.94 -15 40 13.9 22.3 Allen 21.99225 12 29 12.63 -15 40 12.2 " 21.99547 12 29 12.29 -15 40 10.7 " 21.99876 12 29 11.95 -15 40 09.1 " 22.00191 12 29 11.63 -15 40 07.8 " The indicated correction to the prediction by S. Nakano on MPC 79350 is Delta(T) = +5.0 days. The following linked orbital elements by Williams are from 59 observations spanning 2004 Sept. 2-2015 Apr. 22 (mean residual 0".5). Additional orbital elements for the missed 2010 apparition and an ephemeris appear on 2015-H86. Epoch = 2015 Aug. 6.0 TT T = 2015 Aug. 7.31079 TT Peri. = 0.74283 e = 0.6845454 Node = 295.94922 2000.0 q = 0.9770129 AU Incl. = 4.89973 a = 3.0971582 AU n = 0.18082521 P = 5.45 years NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2015 CBAT 2015 April 22 (CBET 4094) Daniel W. E. Green