Electronic Telegram No. 4246 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 C/2015 VL62 = 2015 YY6 On Jan. 23, E. Lilly and R. Weryk, Institute for Astronomy, University of Hawaii, reported the discovery of a comet of an apparent comet in four i-band exposures taken on Jan. 23.3 UT with the 1.8-m Pan-STARRS1 telescope on Haleakala (discovery observations tabulated below); the object was marginally cometary in appearance, with FHWM = 1".3 (vs. 1".0 for adjacent stars), but there was evidence of a faint tail, extending towards the east for approximately 3". 2016 UT R.A. (2000) Decl. Mag. Jan. 23.29589 3 20 20.56 +26 50 15.5 19.8 23.30534 3 20 20.21 +26 50 13.8 19.9 23.31480 3 20 19.86 +26 50 12.4 19.5 23.32433 3 20 19.51 +26 50 10.8 19.7 The object was posted on the Minor Planet Center's PCCP webpage. Weryk subsequently reported that he identified observations of this object in three w-band Pan-STARRS1 images acquired on 2015 Dec. 16.3 UT, the object then appeared asymmetric, with a small extension < 2" long towards the east, with the comet's head having FWHM about 1".6 (vs. 1".2 seeing); the magnitude was measured to be 19.8-19.9. Weryk then also suggested identity of this object with 2015 YY6, an apparently asteroidal object of red mag 19.0-19.5 reported by W. K. Y. Yeung and observed on 2015 Dec. 18 and 19 with a 0.7-m f/3 reflector near Mayhill, NM, USA (and published with that designation on MPS 662873). G. V. Williams confirmed these identifications and then found also an identification with an object detected in 2015 November at Mount Lemmon in observations made by R. G. Matheny (Nov. 2) and by E. J. Christensen (Nov. 3), at which time those observations had been given the minor-planet designation 2015 VL62 on MPS 645811. These observations are tabulated below: 2015 UT R.A. (2000) Decl. Mag. Observer Nov. 2.49797 4 39 22.74 +29 45 27.5 20.7 Matheny 2.50207 4 39 22.55 +29 45 27.4 20.2 " 2.50617 4 39 22.30 +29 45 27.3 20.7 " 2.51027 4 39 22.09 +29 45 27.1 20.3 " 3.42074 4 38 32.46 +29 45 24.2 20.4 Christensen 3.42766 4 38 32.09 +29 45 24.2 20.1 " 3.43459 4 38 31.69 +29 45 23.9 20.5 " 3.44151 4 38 31.31 +29 45 23.9 20.3 " Dec. 18.13517 3 51 12.64 +28 38 36.0 19.1 Yeung 18.25109 3 51 05.33 +28 38 18.0 19.3 " 19.12080 3 50 10.66 +28 35 52.4 19.5 " 19.23661 3 50 03.29 +28 35 33.3 19.0 " Observations of 2015 VL62 were also reported via the Catalina Sky Survey on 2015 Nov. 8.4 UT (at mag 19.9-20.2) and Dec. 8.2 (when it had brightened to mag 19.2-19.7); these were identified by Williams after the link was made between the Nov. 2-3 and Dec. 18-19 observations. After the object was posted on the PCCP webpage, other CCD astrometrists have also commented on the objects cometary appearance. H. Sato, Tokyo, Japan, writes that twelve stacked 60-s exposures taken on Jan. 29.1 with an iTelescope 0.43-m f/6.8 astrograph (+ luminance filter) near Mayhill, NM, USA, show the object to be strongly condensed with a coma 8" in diameter and a hint of tail 15" long toward p.a. 270 degrees; the w-band magnitude was 18.8 as measured within a circular aperture of radius 5".7. V-band images taken by W. H. Ryan and E. V. Ryan with the Magdalena Ridge Observatory 2.4-m f/8.9 reflector on Jan. 29.1 show a short, distinct tail at p.a. about 80 deg; the magnitude was measured to be 19.9-20.0. The available astrometry (spanning 2015 Nov. 2-2016 Jan. 29), the following hyperbolic orbital elements by G. V. Williams, and an ephemeris appear on MPEC 2016-B85. Epoch = 2017 Sept. 4.0 TT T = 2017 Aug. 28.74212 TT Peri. = 128.32371 e = 1.0018347 Node = 94.55854 2000.0 q = 2.7232191 AU Incl. = 165.61705 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2016 CBAT 2016 January 29 (CBET 4246) Daniel W. E. Green