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IAUC 9087: C/2009 U4

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                                                  Circular No. 9087
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://www.cfa.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)


COMET C/2009 U4 (McNAUGHT)
     Robert H. McNaught, Australian National University, reports
his discovery of a comet with a weak-to-moderately condensed 30"
coma on CCD images (discovery observation tabulated below) taken
with the 0.5-m Uppsala Schmidt telescope at Siding Spring
Observatory.  McNaught subsequently identified images of the comet
that he had taken on Oct. 22.46 UT, noting it to be then rather
diffuse, but with its coma clearly extended in p.a. 50 deg, on
images taken for C/2009 R1; observations were then identified on
Uppsala Schmidt frames taken by G. J. Garradd on Oct. 11.5, when
the object again appeared quite diffuse with the coma extended to
the northeast.  After posting on the Minor Planet Center's 'NEOCP'
webpage, other CCD astrometrists also remarked on the object's
cometary appearance.  C. Jacques and E. Pimentel (Belo Horizonte,
Minas Gerais, Brazil, 0.30-m reflector, Oct. 23.99) report that ten
stacked 30-s exposures show a very diffuse coma with diameter 22".
G. Hug (Scranton, KS, U.S.A., 0.56-m reflector, Oct. 24.1) notes
the object as diffuse with a slight elongation in p.a. 330 deg.
R-band images taken by W. H. Ryan and E. V. Ryan (Magdalena Ridge
Observatory, 2.4-m reflector, Oct. 24.1) show a northward tail.  A.
Boattini (Mt. Lemmon 1.5-m reflector, Oct. 24.1) finds a fairly
strongly condensed coma of diameter 15" with a faint fan-shaped
tail about 110 deg wide.  J. E. McGaha (Tucson, AZ, U.S.A., 0.36-m
Schmidt-Cassegrain reflector, Oct. 24.1) writes that ten stacked
60-s images show a round 8" coma with a faint, broad, fan tail 15"
long in p.a. 60 deg.  H. Sato (Tokyo, Japan, remotely using a
0.25-m reflector at the RAS Observatory near Mayhill, NM, U.S.A.,
on Oct. 24.1) finds a diffuse coma of diameter 20".

     2009 UT             R.A. (2000) Decl.       Mag.   Observer
     Oct. 23.49110   20 48 45.26   -31 08 33.6   16.8   McNaught

Additional astrometry, the following preliminary elliptical orbital
elements, and an ephemeris appear on MPEC 2009-U76:

     T = 2009 Sept.11.164 TT          Peri. = 261.923
     e = 0.74565                      Node  =  54.361   2000.0
     q = 1.67495 AU                   Incl. =  10.218
       a =  6.58532 AU     n = 0.058323     P =  16.9 years

                      (C) Copyright 2009 CBAT
2009 October 24                (9087)            Daniel W. E. Green

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