[IAUC] CBET 3321: 20121202 : COMET C/2012 V4

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 3321
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 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 C/2012 V4
     [Editor's note:  This replaces the text on CBET 3320 (date correction).]
     Rob Matson, Newport Coast, CA, U.S.A., reports that he found images of
a possible comet in SWAN/SOHO spacecraft images taken in November (his
measurements provided below in MPC format, with the first of each two-line
set of astrometry showing the R.A. and Decl. and the second line giving
the spacecraft coordinates).

    CK12V040  S2012 11 07.5     19 59.4     -52 56                           249
    CK12V040  s2012 11 07.5     1 -495068.34 -1260522.88 -518894.899         249
    CK12V040  S2012 11 10.5     19 45.2     -46 52                           249
    CK12V040  s2012 11 10.5     1 -417622.35 -1306343.62 -551398.830         249
    CK12V040  S2012 11 11.5     19 41.3     -44 48                           249
    CK12V040  s2012 11 11.5     1 -391884.74 -1320111.59 -561580.297         249
    CK12V040  S2012 11 13.5     19 35.2     -41 12                           249
    CK12V040  s2012 11 13.5     1 -340679.09 -1345149.81 -580848.200         249
    CK12V040  S2012 11 19.5     19 23.7     -35 03                           249
    CK12V040  s2012 11 19.5     1 -194219.38 -1398698.26 -629304.964         249

Matson computed parabolic orbital elements (T = 2012 Dec. 6, q = 0.75 AU, i =
161 deg) that he circulated via e-mail to solicit ground-based observations
to seek confirmation of a possible comet.  Terry Lovejoy (Thornlands, Qld.,
Australia) obtained images through trees and in moonlight on Nov. 29.4 UT
(astrometry tabulated below) with a 20-cm reflector that showed a
well-condensed comet of diameter 2' and mag about 10.  R. H. McNaught also
quickly obtained images with the 0.5-m Uppsala Schmidt telescope at Siding
Spring, confirming the SWAN object to be a comet, nothing a "spring-onion"
appearance with a strongly condensed condensation and a coma of diameter 1'.0
and a 6' tail in p.a. 101 deg.

     2012 UT             R.A. (2000) Decl.       Mag.   Observer
     Nov. 29.39934   19 16 21.76   -29 16 55.3   11.5   Lovejoy
          29.42881   19 16 20.04   -29 15 26.2   11.6     "
          30.38652   19 15 28.09   -28 29 57.2   11.6     "
          30.38694   19 15 28.07   -28 29 56.3   11.5     "
          30.39175   19 15 27.83   -28 29 41.8   11.8     "
          30.40102   19 15 27.28   -28 29 16.2   11.6     "
          30.41491   19 15 26.56   -28 28 36.5   11.7     "
          30.41944   19 15 26.33   -28 28 24.3   11.7     "
          30.42108   19 15 26.18   -28 28 19.6   10.9   McNaught
          30.42221   19 15 26.12   -28 28 16.7   10.9     "
          30.42410   19 15 25.99   -28 28 10.5   10.9     "
          30.42604   19 15 25.88   -28 28 05.0   10.8     "
          30.43043   19 15 25.67   -28 27 52.9   10.9     "

Other CCD astrometrists have also made comments on the comet's appearance.
Y. Sugiyama (Hiratsuka-shi, Kanagawa, Japan; 0.25-m f/5 reflector; Dec. 1.4)
reports a moderately condensed coma of diameter about 30".  Images by C. Bell
(Vicksburg, MS, U.S.A.; 0.3-m Schmidt-Cassegrain reflector; Dec. 2.0) show a
central condensation of diameter 13" and a coma diameter of 40".  H. Sato
(Tokyo, Japan; 0.51-m f/6.8 astrograph remotely at the RAS Observatory near
Mayhill, NM, U.S.A.; Dec. 2.0) found a strongly condensed round coma of
diameter 105" in stacked images; he found the total V-band magnitude to be
10.6 as measured within a circular aperture of radius 52".5.  A visual
observation by A. Hale (Cloudcroft, NM, U.S.A., 0.41-m reflector) on Dec.
1.06 shows a moderately condensed coma of diameter 2'.2 and total mag 9.4
(low altitude; corrected for atmospheric extinction).
     Maik Meyer, Limburg, Germany, suggested that the orbital elements of
comet C/2012 V4 are smilar to those of D/Pons-Gambart (1827 M1).  S. Nakano
(Sumoto, Japan) then tried linking the orbit but could not find anything
where the 1827 residuals are smaller than 0.5 deg; he suggests that if the
identification is correct, the period could be 62.1 yr, adding that the
comet would have passed 1.27 AU from Saturn on 1830 June 22 and 1.30 AU
from Uranus on 1959 May 27.
     G. V. Williams, Minor Planet Center, writes that an orbit based on just
the 2012 observations can have 1/a ranging from about 0.1 to 0, meaning that
the period is essentially indeterminate.  The solution presented below is
based on the assumption that this is a return of D/1827 M1 (Pons-Gambart), a
supposition based on the similarity of elements by Williams (and a suggestion
made independently by M. Meyer), and that two returns were missed.  The 1827
observations are known to be extremely noisy, and this orbit represents
seven normal places to about 0.5 deg.  The 2012 astrometry and an ephemeris
appears on MPEC 2012-X02.

                    Epoch = 2012 Dec. 19.0 TT
     T = 2012 Dec. 19.7659 TT         Peri. =  20.5369
     e = 0.948936                     Node  = 320.8075  2000.0
     q = 0.801202 AU                  Incl. = 136.8482
       a = 15.690006 AU    n = 0.0158588    P =  62.149 years


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

                         (C) Copyright 2012 CBAT
2012 December 2                  (CBET 3321)              Daniel W. E. Green