[IAUC] CBET 4251: 20160202 : COMET P/2015 PD_229

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 4251
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET P/2015 PD_229
     David A. Cameron, University of Rochester, reported astrometry on 2015
Aug. 14 to the Minor Planet Center of an apparent comet found on CCD images
taken to search for trans-neptunian objects on 2015 Mar. 27 and 28 with the
4.0-m Blanco reflector (+ DECam + broad "VR"-band filter) at Cerro Tololo by
E. E. Mamajek, F. Moolekamp, D. J. James, and himself; the object was
apparently found by Cameron and described by him as a pointlike source (1".1
head) with a thin tail about 1".1 wide and approximately 12" long, trailing
directly opposite the direction of motion of the comet.  Their images have
been posted at URL http://www.pas.rochester.edu/~emamajek/DECAM/COMET1/.
     After Cameron's report was received, a discovery report of an apparently
asteroidal object observed on 2015 Aug. 15 with a 0.4-m f/2.4 reflector of
the International Scientific Optical Network (ISON) at Siding Spring was
received from L. Elenin; it received the minor-planet designation 2015
PD_229 when it was announced by the Minor Planet Center (cf. MPECs 2015-Q08,
2015-Q15) without linkage to the May comet.  When the linkage was made and
published on MPEC 2015-Q17, G. V. Williams wrote:  "This object was reported
as a comet (without any details on appearance) by the DECam team on Aug. 14.
It was reported as a NEOCP candidate on Aug. 16 by the ISON-Siding Spring
team.  Details on the cometary appearance in May were submitted on Aug. 18,
following prompting by [myself].  The linkage of the two sets of observations
was made after the object was removed from the NEOCP and designated.  None of
the August reports have mentioned detecting cometary features, hence this
announcement under a minor-planet designation.  There is a roughly two-
magnitude discrepancy in the absolute magnitudes determined from the May
observations alone and from the August observations alone.  Confirmation of
any possible cometary activity is therefore very desireable."  Even though
no further cometary activity has been reported by observers elsewhere, the
object was announced yesterday on MPEC 2016-C2 as a comet -- using the name
"ISON-Cameron", which is under review by the IAU Working Group on Small
Bodies Nomenclature (vs. the standard chronologically ordered "Cameron-ISON").
     The discovery astrometry is tabulated below.

     2015 UT             R.A. (2000) Decl.       Mag.   Observer
     May  27.36183   22 42 27.81   - 8 47 57.6   22.3   Mamajek
          27.38330   22 42 28.38   - 8 47 54.0   22.8     "
          27.40479   22 42 28.93   - 8 47 50.4   22.6     "
          27.42635   22 42 29.49   - 8 47 46.8   22.2     "
          28.36108   22 42 54.13   - 8 45 12.3   22.1     "
     Aug. 15.71559   22 41 43.13   - 8 37 10.0   18.6   Elenin
          15.72528   22 41 42.89   - 8 37 11.8   19.0     "
          15.73484   22 41 42.63   - 8 37 12.7   19.2     "

     The available astrometry (spanning 2015 May 27-Dec. 9), the following
elliptical orbital elements by G. V. Williams, and an ephemeris appear on
MPEC 2016-C2.

                    Epoch = 2015 Aug.  6.0 TT
     T = 2015 Aug. 14.52845 TT        Peri. = 352.40460
     e = 0.3267690                    Node  = 342.77290 2000.0
     q = 4.8320382 AU                 Incl. =   2.02702
       a =  7.1773857 AU   n = 0.05125717   P =  19.229 years


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

                         (C) Copyright 2016 CBAT
2016 February 2                  (CBET 4251)              Daniel W. E. Green