Electronic Telegram No. 4323 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 SV = P/2009 Q9 (PANSTARRS) Eva Lilly, Robert Weryk, and Richard Wainscoat report the discovery of an apparent comet in four r-band exposures obtained with the 1.8-m Pan-STARRS1 telescope at Haleakala on Sept. 21 UT (discovery observations tabulated below, along with pre-discovery Pan-STARRS1 images from June 20 and Sept. 19 that were identified later). In each of the September images, the object shows a broad, low-surface-brightness tail extending to the south for approximately 6", and the full-width-at-half-maximum (FWHM) of the nucleus in a co-added image is 1".5, compared to 1".1 arc for nearby field stars. Wainscoat and M. Micheli add that six 60-s w-band confirming images were obtained using the Canada-France-Hawaii Telescope at Mauna Kea on 2016 Sept. 23.5 in relatively poor observing conditions (seeing 1".1); nevertheless, the images clearly show that the comet is extended, with its nuclear condensation showing a FWHM of approximately 1".5, along with a broad, low-surface-brightness tail extending to the south of the nuclear condensation for approximately 10". 2016 UT R.A. (2000) Decl. Mag. June 20.57485 23 30 49.32 +10 29 42.1 21.5 20.58306 23 30 49.86 +10 29 48.8 21.8 20.59125 23 30 50.41 +10 29 55.3 21.6 Sept.19.50370 23 53 11.16 +21 44 39.3 19.2 19.51579 23 53 10.69 +21 44 36.4 19.4 21.47095 23 52 00.02 +21 36 36.4 19.3 21.48382 23 51 59.52 +21 36 32.8 19.3 21.49672 23 51 59.02 +21 36 29.4 19.2 21.50970 23 51 58.52 +21 36 25.9 19.3 After the comet was posted on the Minor Planet Center's NEOCP webpage, H. Sato (Tokyo, Japan) reported that eight stacked 20-s exposures taken with an 0.61-m f/6.5 astrograph (+ luminance filter) on Sept. 22.3 UT shows a round, strongly condensed coma 8" in diameter with a hint of tail 10" long toward p.a. 225 degrees; the w-band magnitude was 18.2 as measured within a circular aperture of radius 5".0. G. V. Williams identified this comet with single night astrometry obtained via the Catalina Sky Survey by A. Boattini on 2009 Aug. 26.3 UT and by A. R. Gibbs on 2009 Oct. 19.1, as tabulated below. 2009 UT R.A. (2000) Decl. Mag. Observer Aug. 26.26973 22 01 33.27 + 9 21 15.3 19.6 Boattini 26.27773 22 01 32.91 + 9 21 14.0 19.9 " 26.28572 22 01 32.62 + 9 21 14.0 19.6 " 26.29365 22 01 32.19 + 9 21 12.3 19.3 " Oct. 19.13036 21 50 25.76 + 5 34 04.0 19.5 Gibbs 19.13642 21 50 25.98 + 5 34 02.5 20.1 " 19.14249 21 50 26.12 + 5 34 01.2 19.2 " 19.14863 21 50 26.30 + 5 33 59.9 19.6 " The available astrometry [including Mt. Lemmon observations from 2016 July 9.4 UT (with the magnitude measured then as 20.5-21.1) and observations by L. Elenin from 2016 Sept. 5.1 using a 0.4-m f/3 reflector at the ISON-NM Observatory near Mayhill, NM, USA (with the magnitude measured then as 19.4-19.8)], the following linked orbital elements by G. V. Williams, and an ephemeris appear on MPEC 2016-S61. Epoch = 2009 Nov. 25.0 TT T = 2009 Nov. 5.14204 TT Peri. = 98.45572 e = 0.3865279 Node = 261.08759 2000.0 q = 2.2116281 AU Incl. = 11.75112 a = 3.6050995 AU n = 0.14398863 P = 6.84 years Epoch = 2016 Sept. 9.0 TT T = 2016 Sept.11.38651 TT Peri. = 98.44571 e = 0.3843920 Node = 261.04761 2000.0 q = 2.2239959 AU Incl. = 11.74387 a = 3.6126821 AU n = 0.14353554 P = 6.87 years NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2016 CBAT 2016 September 27 (CBET 4323) Daniel W. E. Green