Electronic Telegram No. 2779
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@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET P/2011 P1 (McNAUGHT)
     R. H. McNaught reports his discovery of a comet (discovery observation
tabulated below) on CCD images taken with the 0.5-m Uppsala Schmidt telescope
at Siding Spring; the discovery images show the comet to be diffuse with a
circular coma of diameter about 20"; four stacked images later show a
condensation and extension to the north and south.  Eight stacked 60-s
exposures by McNaught on Aug. 2.7 UT show a similar-sized coma extended from
p.a. 30-210 deg with an apparent tail toward the west.  Ten stacked 60-s
images taken on Aug. 3.7 show the eastern edge of the coma to be much brighter
extending 10" in p.a. 10 deg and 13" in p.a. 215 deg, like a tail and an
anti-tail (but from previous images, this appears to be the eastern edge of
the coma).  Following posting on the Minor Planet Center's NEOCP webpage,
other CCD astrometrists also have commented on the object's cometary
appearance.  H. Sato (Tokyo, Japan) obtained images remotely with a 0.51-m
f/4.5 reflector at the RAS Observatory near Mayhill, NM, U.S.A., on Aug.
2.4 that show a strongly condensed coma 12" in diameter with a 45" tail;
the total red mag was measured within a 6".4 circular aperture to be 17.8.
G. Masi, U. Masi, and G. Luccone write that five stacked 300-s images
taken with a 0.43-m f/6.8 reflector at Ceccano, Italy, on Aug. 3.1 clearly
show a fuzzy object with a coma/tail at least 20" in size, elongated
toward the northeast/southwest.  Images taken on Aug. 4.4 by R. Holmes
(Ashmore, IL, U.S.A.) with a 0.61-m f/4 astrograph, and measured by S.
Foglia and T. Vorobjov, show a 12" coma and a tail 30" long in p.a. 210
deg in five stacked 60-s images.

     2011 UT             R.A. (2000) Decl.       Mag.   Observer
     Aug.  1.75579    2 30 48.06   +17 06 42.8   18.5   McNaught

The available astrometry, the following very preliminary elliptical orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2011-P19.

     T = 2009 Mar. 24.838 TT          Peri. = 228.841
     e = 0.31349                      Node  =   4.413   2000.0
     q = 2.34637 AU                   Incl. =   5.431
       a =  3.41785 AU     n = 0.155982     P =   6.32 years



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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2011 CBAT
2011 August 5                    (CBET 2779)              Daniel W. E. Green