Central Bureau for Astronomical Telegrams

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IAUC 9123: COMET C/2010 DG_56 (WISE); 2009 QY_6 AND 2010 CG_55; COMET 29P/SCHWASSMANN-WACHMANN

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IAUC number 

                                                  Circular No. 9123
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  D. W. E. Green, Room 209; Department of
 Earth and Planetary Sciences; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
CBAT@IAU.ORG; CBATIAU@EPS.HARVARD.EDU
URL http://www.cfa.harvard.edu/iau/cbat.html  ISSN 0081-0304


COMET C/2010 DG_56 (WISE)
     D. J. Tholen, University of Hawaii (UH), reports that three
300-s exposures of 2010 DG_56, an object with a retrograde orbit
discovered by the WISE satellite (discovery observation tabulated
below; cf. MPEC 2010-D79, MPS 314003-314004), taken by M. Micheli,
J. Gazak, and Tholen with the UH 2.24-m reflector on Mar. 5.3 UT,
show a very faint tail extending at least 3" to the east-southeast,
with the coma being about 0".3 larger than stars of similar
brightness; Tholen adds that earlier Mauna Kea images from Feb. 20
and 21 show no obvious asymmetry.  Following Tholen's report, A.
Mainzer (Jet Propulsion Laboratory) notes that WISE 12-micron
images show the object to have a "soft" condensed nuclear region of
size about 5"-6" with a 'hazy' coma extending about 10" around the
central core.

     2010 UT             R.A. (2000) Decl.       Observer
     Feb. 18.00105    4 30 29.32   - 2 42 04.7   WISE

The recent astrometry, the following parabolic orbital elements,
and an ephemeris appear on MPEC 2010-E43.

     T = 2010 May  13.5729 TT         Peri. = 317.0731
                                      Node  =   4.0718  2000.0
     q = 1.612228 AU                  Incl. = 160.3957


2009 QY_6 AND 2010 CG_55
     More apparently asteroidal objects with retrograde orbits have
been found recently, including 2009 QY_6 (T = 2009 Oct. 4, q = 2.07
AU, i = 138 deg, P = 44 years; cf. MPO 167745); and 2010 CG_55 (T =
2010 Oct. 8, q = 2.86 AU, i = 146 deg, P = 93 years; cf. MPO 171878).
There are now 27 such objects known (all but two having perihelion
distances inside the orbit of Jupiter, and 22 having q < 4 AU),
including numbered objects (20461) = 1999 LD_31 (cf. IAUC 7208) and
(65407) 2002 RP_120.


COMET 29P/SCHWASSMANN-WACHMANN
     Additional visual total-magnitude estimates (cf. IAUC 9116):
Feb. 10.50, 10.7 (C. Wyatt, Walcha, NSW, Australia, 25-cm
reflector); 19.61, 10.6 (M. Mattiazzo, Castlemaine, Victoria,
Australia, 20-cm reflector); Mar. 1.81, 10.8 (J. J. Gonzalez,
Asturias, Spain, 20-cm reflector); 5.88, 10.6 (U. Pilz, Leipzig,
Germany,  32-cm reflector); 8.89, 11.2 (Gonzalez).

                      (C) Copyright 2010 CBAT
2010 March 10                  (9123)            Daniel W. E. Green

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