[IAUC] IAUC 9204: C/2011 G1; P/2011 A2 [25139-2011/04-R1]

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                                                  Circular No. 9204
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 G1 (McNAUGHT)
     R. H. McNaught reports his discovery of a comet (discovery
observation tabulated below) on CCD images obtained with the 0.5-m
Uppsala Schmidt telescope at Siding Spring; the object has a
moderate- to poorly-condensed central condensation inside a
circular 30" coma.  After posting on the Minor Planet Center's
'NEOCP' webpage, other CCD astrometrists have also commented on the
object's cometary appearance from exposures obtained on Apr. 6 UT.
R. Holmes, T. Linder, and V. Hoette obtained images remotely on
Apr. 6.18 with a 0.41-m f/11 Ritchey-Chretien telescope at Cerro
Tololo, the comet showing a 10" coma with a faint, broad tail
extending 16" in p.a. 42.8 deg in fifteen co-added 15-s exposures.
G. Sostero and E. Guido remotely used a 0.15-m f/7.3 refractor at
the Tzec Maun Observatory (near Moorook, Australia) to find a coma
nearly 8" in diameter with a sharp central condensation and a short
tail about 15" long toward p.a. 15 deg in forty stacked 60-s
exposures.  S. Foglia writes that images obtained by P. Miller, P.
Roche, A. Tripp, R. Miles, R. Holmes, L. Buzzi, and himself with
the 2.0-m f/10 'Faulkes Telescope North' at Haleakala show a
diffuse 6" coma in bad seeing.  H. Sato (Tokyo, Japan) obtained
images remotely with an RAS Observatory 0.30-m f/6.5 Ritchey-
Chretien telescope near Officer, Australia, showing a strongly
condensed 8" coma; R. Ligustri (Udine, Italy) evidently used the
same instrument some 3 hr later to find a faint coma elongated
toward p.a. 45 deg.

     2011 UT             R.A. (2000) Decl.       Mag.   Observer
     Apr.  5.74306   14 26 15.85   -38 59 25.4   17.3   McNaught

The available astrometry, the following preliminary parabolic
orbital elements (from 39 observations, Apr. 5-6) by G. V. Williams,
and an ephemeris appear on MPEC 2011-G49.

     T = 2011 Sept.24.386 TT          Peri. =  13.234
                                      Node  = 158.438   2000.0
     q = 1.81401 AU                   Incl. = 161.446


COMET P/2011 A2 (SCOTTI)
     This comet (cf. IAUC 9192) has been found to be of short
period; elliptical orbital elements by Williams from MPC 74249:
Epoch = 2010 Dec. 30.0 TT, T = 2010 Dec. 22.5222 TT, q = 1.559036
AU, e = 0.499307, Peri. = 94.5916 deg, Node = 54.7422 deg, i =
4.4742 deg (equinox 2000.0), P = 5.49 years.

                      (C) Copyright 2011 CBAT
2011 April 6                   (9204)            Daniel W. E. Green