[IAUC] IAUC 9193: C/2011 A3 [25139-2011/04-R1]

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                                                  Circular No. 9193
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
New postal address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
CBATIAU en EPS.HARVARD.EDU           ISSN 0081-0304
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Prepared using the Tamkin Foundation Computer Network


COMET C/2011 A3 (GIBBS)
     A. R. Gibbs reports his discovery of a comet on CCD images
taken with with the Catalina 0.68-m Schmidt reflector (discovery
observation tabulated below); Gibbs reported that four 22-s
exposures showed a 5" tail in p.a. 270 deg, and the FWHM of the
comet's image was 6".4 larger than images of nearby stars of
similar brightness.  After posting on the Minor Planet Center's
'NEOCP' webpage, other CCD astrometrists have also commented on the
object's cometary appearance.  L. Buzzi (Varese, Italy, 0.38-m
f/6.8 reflector; seeing about 2"; Jan. 16.15-16.22 UT) writes that
stacked images reveal a condensed coma that is 10" in diameter with
a tail 20" long in p.a. about 280 deg.  H. Sato (Tokyo, Japan;
remotely using a 0.43-m f/6.8 reflector at Nerpio, Spain; Jan.
16.23) found a condensed coma of diameter 6" and a faint tail of
length 20" toward p.a. 275 deg.  S. Foglia reports that ten stacked
120-s exposures taken remotely by S. Baroni, L. Buzzi, P. Concari,
G. Galli, M. Tombelli, and himself on Jan. 16.4 and 17.5 with a
0.18-m f/7.3 refractor at the Tzec Maun Observatory (near
Cloudcroft, NM, U.S.A.) show a 10" round coma.  R. Ligustri (Udine,
Italy; remotely using a 0.25-m f/3.3 reflector at the RAS
Observatory near Mayhill, NM, U.S.A.; Jan. 16.4) measures a coma
diameter of about 20", elongated toward p.a. 270 deg.  K. Kadota
(Ageo, Japan, 0.25-m f/5 reflector) reports total mag 17.9-18.0,
coma diameter 0'.3, and a hint of a tail toward the west on images
taken on Jan. 16.78 and 17.70.  E. Guido (Castellammare di Stabia,
Italy) reports that fourteen stacked 120-s unfiltered images taken
remotely by G. Sostero (Povoletto, Italy) and himself on Jan. 17.4
with an RAS Observatory 0.25-m f/3.4 reflector located near Mayhill
show a sharp coma nearly 8" in diameter (red mag 17.5-17.6) with a
faint tail about 15" long toward p.a. 280 deg.  In turn, Sostero
reports that 27 stacked 180-s exposures taken remotely on Nov. 17.5
with a Tzec Maun Observatory 0.35-m f/3.8 reflector shows a coma
diameter of about 10" with a central condensation and a faint tail
about 12" long toward p.a. 280 deg.

     2011 UT             R.A. (2000) Decl.       Mag.   Observer
     Jan. 15.51340   13 27 52.66   +16 06 52.8   18.4   Gibbs

The available astrometry, the following very preliminary parabolic
orbital elements by G. V. Williams, and an ephemeris appear on MPEC
2011-B07.

     T = 2011 Oct.  4.469 TT          Peri. = 184.623
                                      Node  = 108.605   2000.0
     q = 1.09867 AU                   Incl. =  22.805

                      (C) Copyright 2011 CBAT
2011 January 17                (9193)            Daniel W. E. Green