Electronic Telegram No. 4312 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 Q3 = 2008 SH164 (LINEAR) A comet found by R. A. Kowalski on CCD images taken with the 1.5-m reflector at Mount Lemmon on Aug. 29.35-29.37 UT (discovery observations tabulated below) has been found to be a re-discovery of an apparently asteroidal object discovery by the LINEAR survey in 2008 and then given the minor-planet designation 2008 SH164 (for which there were observations spanning 2008 Sept. 2-Dec. 4; discovery observations also tabulated below). Kowalski reported a coma approximately 10" in diameter, elongated east-west with some impression of a tail extending 1' in p.a. 260 in good seeing and good transparency; four co-added 60-s follow-up exposures taken by Kowalski on Aug. 29.4 show a diffuse region surrounding the coma and a diffuse tail. 2008 UT R.A. (2000) Decl. Mag. Observer Sept.28.22912 1 08 52.62 + 4 36 42.4 19.8 LINEAR 28.24133 1 08 52.23 + 4 36 38.4 20.2 " 28.25349 1 08 51.72 + 4 36 35.6 20.2 " 28.26565 1 08 51.24 + 4 36 31.8 20.2 " 28.27780 1 08 50.88 + 4 36 28.5 20.2 " 29.28431 1 08 14.77 + 4 31 56.1 19.6 " 29.29660 1 08 14.27 + 4 31 53.4 20.1 " 29.30888 1 08 13.71 + 4 31 49.7 20.4 " 29.32118 1 08 13.33 + 4 31 45.8 20.1 " 29.33345 1 08 12.94 + 4 31 42.3 20.0 " 2016 UT R.A. (2000) Decl. Mag. Observer Aug. 29.34984 0 38 42.54 + 2 24 55.3 18.9 Kowalski 29.35925 0 38 42.30 + 2 24 53.5 18.8 " 29.36874 0 38 42.11 + 2 24 51.7 18.7 " 29.37823 0 38 41.97 + 2 24 49.9 18.7 " 29.41052 0 38 41.24 + 2 24 43.6 18.7 " 29.41579 0 38 41.16 + 2 24 42.4 18.8 " 29.42088 0 38 41.08 + 2 24 41.5 18.9 " 29.42598 0 38 40.95 + 2 24 40.8 18.9 " After the comet was posted on the Minor Planet Center's PCCP webpage, other CCD astrometrists have also commented on the object's cometary appearance. Unfiltered CCD images taken by A. Maury and J.-F. Soulier on Aug. 30.2 UT with a 0.4-m f/8 Ritchey-Chretien reflector at San Pedro de Atacama, Chile, show a 14" coma and a tail 13" long in p.a. 250 deg. H. Sato, Tokyo, Japan, writes that eight stacked 60-s images taken with an iTelescope 0.61-m f/6.5 astrograph (+ luminance filter) located at the Sierra Remote Observatory near Auberry, CA, USA, on Aug. 30.34 show a strongly condensed coma 10" in diameter with no tail; the w-band magnitude was 18.7 as measured within a circular aperture of radius 6".3. The indicated correction to the prediction for 2008 SH164 on MPO 149062 is Delta(T) = +0.09 day. The available astrometry from both apparitions (including pre-discovery observations from Spacewatch on 2008 Sept. 2.4 UT, with the magnitude given as 20.1-20.2; and from the Mt. Lemmon Survey on 2008 Sept. 23.35-23.37, with the magnitude given as 18.7-19.4), the following linked orbital elements by G. V. Williams (from 53 observations spanning 2008 Sept. 2-2016 Aug. 30; mean residual 0".6) and an ephemeris appear on MPEC 2016-Q54. Epoch = 2008 May 14.0 TT T = 2008 June 2.60994 TT Peri. = 196.41559 e = 0.2216057 Node = 154.56908 2000.0 q = 3.1369803 AU Incl. = 2.72621 a = 4.0300660 AU n = 0.12182483 P = 8.09 years Epoch = 2016 July 31.0 TT T = 2016 July 16.00857 TT Peri. = 196.57969 e = 0.2193927 Node = 154.51823 2000.0 q = 3.1583380 AU Incl. = 2.72472 a = 4.0460010 AU n = 0.12110584 P = 8.14 years NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2016 CBAT 2016 August 31 (CBET 4312) Daniel W. E. Green