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IAUC 9058: C/2009 O3; C/2008 Y18

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IAUC number 

                                                  Circular No. 9058
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 O3 (HILL)
     R. E. Hill reports his discovery of a comet with the Catalina
0.68-m Schmidt telescope (discovery observation tabulated below),
noting that co-added 30-s exposures show a nuclear condensation
elongated northeast-southwest and a 6" x 10" coma with a broad,
diffuse tail about 2' long in p.a. 260 deg (though on July 30.4 UT,
the coma < 2").  After posting on the 'NEOCP' webpage, other CCD
astrometrists have noted the cometary appearance.  Below are given
measured coma diameters and tail information from images obtained
July 30.0-30.5:  10" coma (diffuse with central condensation), 30"
tail in p.a. 250 deg (P. Birtwhistle, Great Shefford, Berkshire,
England, 0.40-m reflector); strong central condensation with a tail
at least 40" long in p.a. 255 deg (L. Buzzi, Varese, Italy, 0.60-m
reflector); tail > 1' long toward p.a. 245 deg (E. Prosperi,
Larciano, Italy, 0.35-m reflector; fifty co-added 30-s exposures
taken by P. Camilleri, E. Guido, G. Sostero, and himself); compact
nuclear condensation and a broad, diffuse tail 27".7 long in p.a.
247.5 deg (R. Holmes and H. Devore, Charleston, IL, U.S.A., 0.61-m
astrograph); about 5" compact coma and a 30" tail in p.a. 225 deg
(E. Guido and G. Sostero, remotely using a 0.25-m reflector near
Mayhill, NM, U.S.A.; six co-added unfiltered 120-s exposures);
round 10" coma (J. E. McGaha, Tucson, AZ, U.S.A., 0.36-m reflector;
five stacked 60-s exposures); faint tail in p.a. about 225 deg (W.
H. Ryan, Magdalena Ridge 2.4-m reflector).

     2009 UT             R.A. (2000) Decl.       Mag.   Observer
     July 29.43294    1 31 27.03   +10 16 52.4   17.5   Hill

The available astrometry, the following preliminary parabolic
orbital elements by B. G. Marsden, and an ephemeris appear on MPEC
2009-O54.

     T = 2009 Apr. 21.770 TT          Peri. = 130.389
                                      Node  = 180.985   2000.0
     q = 1.88365 AU                   Incl. =  12.750


COMET C/2008 Y18 (SOHO)
     Further to IAUC 9042, another Kreutz sungrazer has been found
on SOHO website images, being extremely faint (mag about 8.5-9) and
slightly diffuse in C2 images, and diffuse (mag about 11.5) in
STEREO HI1-A images.

 Comet        2008 UT       R.A.(2000)Decl.   Inst.  F    MPEC
 C/2008 Y18   Dec. 25.829   18 24.5  -24 47   C2*    MK   2009-M41

                      (C) Copyright 2009 CBAT
2009 July 30                   (9058)            Daniel W. E. Green

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