Electronic Telegram No. 3924
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/2014 MG_4 (SPACEWATCH-PANSTARRS)
     An apparently asteroidal object discovered last month on images obtained
by R. A. Mastaler with the Spacewatch 0.9-m f/3 reflector at Kitt Peak, and
given the minor-planet designation 2014 MG_4 (MPS 520101) based on two nights
of Spacewatch astrometry, has been discovered independently as a comet by P.
Veres, R. Wainscoat, L. Denneau, B. Bolin, and M. Micheli on two w-band CCD
exposures taken with the 1.8-m Pan-STARRS reflector at Haleakala on July 25
(the object then showing a broad diffuse tail extending for about 3" spanning
p.a. 200-300 deg, and with a presumed coma larger than nearby stars of
similar brightness).  The discovery observations from both observatories are
tabulated below:

     2014 UT             R.A. (2000) Decl.       Mag.   Observer
     June 20.42262   21 12 49.38   -17 36 26.8          Mastaler
          20.42512   21 12 49.32   -17 36 26.4            "
          20.44043   21 12 49.10   -17 36 25.9            "
          20.44291   21 12 49.05   -17 36 25.9            "
          20.45567   21 12 48.86   -17 36 25.7            "
          20.45894   21 12 48.80   -17 36 25.6            "
     July 25.45790   20 56 37.17   -17 52 17.1   19.4   Pan-STARRS
          25.46988   20 56 36.71   -17 52 17.8   19.6     "

Three follow-up 60-s r-band exposures obtained by Wainscoat using the
Canada-France-Hawaii Telescope on July 26.4 UT (queue observer P. Forshay)
were analyzed by Micheli and Wainscoat; the comet displays a broad tail
approximately 10" long directed toward p.a. about 310 deg, along with a coma
having a condensed core and magnitude 18.7-18.8.  After posting on the Minor
Planet Center's PCCP webpage, other CCD astrometrists have commented on the
object's cometary appearance.  H. Sato (Tokyo, Japan; remotely with an
iTelescope 0.51-m f/6.8 astrograph + luminance filter near Mayhill, NM,
U.S.A.) writes that five stacked 60-s exposures taken on July 27.4 show a
strongly condensed coma 15" in diameter with w-band magnitude 17.6 as
measured within a circular aperture of radius 8".2; he also notes a faint,
curved tail 20" long toward p.a. 295 degrees).  P. Bacci reports that fifty
co-added 30-s exposures taken with a 0.60-m reflector at San Marcello
Pistoiese, Italy, on July 28.0 show the object to be diffuse with a coma
diameter of 10" (red mag 18.0-18.1), elongated in p.a. 285 deg (measured by
Bacci, L. Tesi, and G. Fagioli).
     The available astrometry, the following elliptical orbital elements by
G. V. Williams, and an ephemeris appear on MPEC 2014-O48.

                    Epoch = 2013 May  28.0 TT
     T = 2013 June 13.8751 TT         Peri. = 300.5664
     e = 0.231680                     Node  = 311.8396  2000.0
     q = 3.783037 AU                  Incl. =   9.4896
       a =  4.923776 AU    n = 0.0902104    P =  10.93 years


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2014 CBAT
2014 July 28                     (CBET 3924)              Daniel W. E. Green