Electronic Telegram No. 4140
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)
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Prepared using the Tamkin Foundation Computer Network


COMET P/2015 Q2 (PIMENTEL)
     C. Jacques, Belo Horizonte, MG, Brazil, reports the discovery of a comet
on CCD exposures obtained by Eduardo Pimentel on Aug. 24.2 UT with a 0.45-m
f/2.9 reflector of the SONEAR Observatory at Oliveira (discovery observations
tabulated below).  The object appeared slightly cometary on Aug. 24, but the
reality of the object's features (and indeed the object itself) was
questioned, and so follow-up observations to confirm the object were obtained
by Jacques, Pimentel, and J. Barros with the same telescope on Aug. 27.3 and
31.3; on the 27th, a diffuse object with a 15" coma was identified by Jacques
that he assumed was not the same object observed on the 24th, and he reported
it to the Central Bureau and the Minor Planet Center as an apparent new comet,
with observations given for Aug. 27 and 31.  Later, Jacques concluded that
the object observed on the first night was identical to that observed on the
second and third nights.  Additional CCD images were obtained by Jacques,
Pimentel, and Barros with an iTelescope 0.70-m f/6.6 astrograph at Siding
Spring on Aug. 31.8; ten stacked 120-s exposures show a diffuse coma with
coma diameter 8" and magnitude 17.3-17.7, elongated 10" toward p.a. 310 deg.

     2015 UT             R.A. (2000) Decl.       Mag.   Observer
     Aug. 24.19727    2 58 53.29   -29 26 01.5   18.8   Pimentel
          24.21071    2 58 51.53   -29 27 05.1   19.0     "
          24.22264    2 58 50.16   -29 28 02.4   18.8     "
          27.27769    2 51 31.21   -33 38 55.0   18.6   Jacques
          27.28752    2 51 29.48   -33 39 43.4   18.6     "
          27.29737    2 51 27.78   -33 40 33.8   18.8     "
          31.25581    2 39 06.94   -39 27 44.5   18.3     "
          31.26493    2 39 04.95   -39 28 32.1   18.4     "
          31.27399    2 39 02.92   -39 29 21.9   18.6     "

After the object was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists have commented on the cometary appearance.  E. Guido and
N. Howes found a sharp central condensation surrounded by a diffuse,
irregular coma 5" in diameter and a tail about 10" long in p.a. 315 deg on
thirty stacked 30-s exposures taken with an iTelescope 0.50-m f/6.8
astrograph at Siding Spring on Aug. 31.7 UT.  Sixty 15-s mages taken by A.
Maury and J.-F. Soulier with a 0.4-m f/8 Ritchey-Chretien reflector at San
Pedro de Atacama, Chile, on Sept. 1.3 show an 11" coma and a fan-shaped
tail 18" long that spans p.a. 270-350 deg.
     The available astrometry, the following preliminary elliptical orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2015-R02.

     T = 2015 Sept.10.2333 TT         Peri. = 244.3619
     e = 0.763174                     Node  = 228.2530  2000.0
     q = 1.820327 AU                  Incl. = 146.1815
       a =  7.686337 AU    n = 0.0462514    P =  21.3 years


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

                         (C) Copyright 2015 CBAT
2015 September 2                 (CBET 4140)              Daniel W. E. Green