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IAUC 9132: C/2010 F4

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                                                  Circular No. 9132
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  D. W. E. Green, Room 209; Department of
 Earth and Planetary Sciences; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
CBAT@IAU.ORG; CBATIAU@EPS.HARVARD.EDU
URL http://www.cfa.harvard.edu/iau/cbat.html  ISSN 0081-0304


COMET C/2010 F4 (MACHHOLZ)
     Don Machholz reports his visual discovery of a diffuse comet
with coma diameter about 2' (DC = 2), using a 0.47-m f/4.8
reflector (77x) at his home in Colfax, CA, U.S.A., in the course of
his comet-hunting program on Mar. 23, as tabulated below; no motion
was detected in 20 minutes due to encroaching twilight.  Machholz
found the comet again of similar appearance (the magnitude then
given as 11.5-12) on the morning of Mar. 26, indicating that it is
moving rapidly towards the sun.  Machholz had searched for 607
hours since his previous find on 2004 Aug. 27 (cf. IAUCs 8394,
8395).  After posting on the Minor Planet Center's 'NEOCP' webpage,
three Japanese amateurs have reported confirmation of the new comet.
Y. Ikari (Moriyama, Shiga-ken, 0.26-m reflector + CCD) reports a
coma diameter of 0'.5.  K. Kadota (Ageo, Saitama-ken, 0.25-m
reflector + CCD) finds that his images taken through clouds show
the object to be diffuse (coma diameter 1'.5) with central
condensation and no tail.  K. Yoshimoto (Yamaguchi-ken, 0.25-m
reflector) reports that a visual observation yields total mag 11.0
and coma diameter 1'.3 (DC = 3) on Mar. 26.830 UT.

     2010 UT             R.A. (2000) Decl.       Mag.   Observer
     Mar. 23.526     22 54.2       +31 22        11     Machholz
          26.515     23 23.5       +32 14        12       "
          26.80750   23 25 47.20   +32 13 14.8   13.9   Ikari
          26.81116   23 25 49.37   +32 13 16.8            "
          26.81482   23 25 51.44   +32 13 19.0            "
          26.82056   23 25 54.80   +32 13 22.6            "
          26.82158   23 25 55.40   +32 13 23.3   12.3   Kadota
          26.82296   23 25 56.18   +32 13 23.6            "
          26.82734   23 25 58.73   +32 13 26.3   14.7   Ikari

The following parabolic orbital elements are extremely uncertain:
T = 2010 Apr. 10.669 TT, q = 0.58698 AU, Peri. = 135.062, Node =
245.662, i =  86.831 (equinox 2000.0).  Ephemeris using H_(7.5) =
12.0:

2010 TT     R. A. (2000) Decl.   Delta     r    Elong. Phase   Mag.
Mar. 25    23 08.35   +31 50.0   1.237   0.693   34.1   53.7   11.3
     26    23 17.99   +32 04.4   1.241   0.682   33.3   53.4   11.2
     27    23 27.63   +32 15.1   1.246   0.671   32.5   53.0   11.2
     28    23 37.26   +32 22.1   1.251   0.661   31.7   52.5   11.1
     29    23 46.84   +32 25.3   1.258   0.651   30.9   51.9   11.1
     30    23 56.35   +32 24.8   1.266   0.642   30.1   51.3   11.1
     31    00 05.76   +32 20.6   1.274   0.633   29.3   50.5   11.0

                      (C) Copyright 2010 CBAT
2010 March 26                  (9132)            Daniel W. E. Green

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