[IAUC] CBET 952: 20070503 : COMET C/2006 WD4 (LEMMON)

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                                                  Electronic Telegram No. 952
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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COMET C/2006 WD4 (LEMMON)
     E. Guido and G. Sostero, Castellammare di Stabia, Italy, report that
their remote CCD observations with a 0.15-m f/6 reflector at the Rent-a-Scope
Observatory at Biggera Waters, Queensland, show the Mt. Lemmon discovery
2006 WD4 (cf. MPEC 2006-W61, MPC 189005; discovery observation below) to be
a comet.  The coaddition of eleven unfiltered 60-s exposures on Apr. 30.80 UT
revealed the presence of a spiral-like symmetric coma, spanning almost 20
arcsec, from p.a. 240 deg to p.a. 30 deg (in a counterclockwise direction);
the total mag was close to 14.2 and that of the condensation 15.3-15.4.
The coaddition of nine similar exposures (but in less satisfactory conditions)
on May 2.80 UT showed the presence of an elliptical coma measuring nearly
12 by 18 arcsec, the major axis tilted along a line close to p.a. 235 deg;
the total mag was about 14.1 and that of the condensation 15.4.

     2006 UT             R.A. (2000) Decl.       Mag.
     Nov. 20.32650    3 32 32.53   +28 02 22.0   20.3

     The following orbital elements, together with the Apr. 30-May 2
astrometry, full residuals and an ephemeris, are given on MPEC 2007-J12.

                    Epoch = 2007 Apr. 10.0 TT
     T = 2007 Apr. 28.3951 TT         Peri. = 292.6928
     e = 0.998994                     Node  = 226.7908  2000.0
     q = 0.591207 AU                  Incl. = 152.7038

     With reference to observations by F. Bernardi with the 2.24-m University
of Hawaii reflector on 2006 Dec. 25.4 UT, D. J. Tholen wrote that, although
the object appeared stellar to the eye, the CCD trail of 2006 WD4 was
wider than the trails of two dozen stars nearby.  In the second of the 600-s
exposures the mean stellar trail width was 2.08 +/- 0.05 pixels (0.91 arcsec).
That of 2006 WD4 (FWHM) was 2.3 pixels (1.01 arcsec), about 0.1 pixel wider
than the widest of the stellar sources.  The results were considered
"sufficiently suspicious to warrant further observations as the object
approaches the sun".


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                         (C) Copyright 2007 CBAT
2007 May 3                       (CBET 952)               Brian G. Marsden