[IAUC] IAUC 9106: C/2010 A3; 217P [25139-2010/01-R1]

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                                                  Circular No. 9106
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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COMET C/2010 A3 (HILL)
     R. E. Hill reports his discovery of another comet with the
Catalina 0.68-m Schmidt telescope (discovery observation tabulated
below); four co-added 30-s CCD exposures show a well-condensed
nuclear condensation 4"-5" across with a possible 2" coma beyond
that and a broad, diffuse tail 10"-15" long in p.a. 80 deg.  Four
follow-up co-added 30-s CCD exposures by A. Boattini with the Mt.
Lemmon 1.5-m reflector on Jan. 8.16-8.17 show a well-condensed
comet with a coma about 5"-6" wide and a broad, fan-shaped tail
about 15" long in p.a. 75 deg.  Following posting on the Minor
Planet Center's 'NEOCP' webpage, other CCD astrometrists have also
noted the object's cometary appearance.  A. Novichonok, Kondopoga,
Russia, reports that five stacked 300-s images taken remotely by T.
Kryachko with the 0.3-m f/8 Astrotel reflector at Zelenchukskaya
Station on Jan. 8.7 UT show a round, diffuse coma of diameter 10"
and a wide, faint 15" tail in p.a. 280 deg.  H. Sato (Ota-ku,
Tokyo, Japan, remotely using an RAS Observatory 0.25-m f/3.4
reflector near Mayhill, NM, U.S.A.; Jan. 9.1 UT) finds a 10" coma
elongated toward p.a. 95 deg.  W. H. Ryan (Magdalena Ridge
Observatory, 2.4-m f/8.9 reflector; Jan. 9.12-9.15) notes a coma
and a faint tail in p.a. about 80 deg on R-band images.  E. Guido
(Castellammare di Stabia, Italy) reports that he and G. Sostero
co-added eighteen 120-s unfiltered exposures taken remotely as
done by Sato (above) on Jan. 9.14-9.16, showing a coma nearly 10"
in diameter, slightly elongated toward p.a. 50 deg.  K. Kadota
(Ageo, Saitama-ken, Japan, 0.25-m f/5 reflector; Jan. 9.5) reports
the comet to be diffuse with central condensation, with a coma
diameter of 0'.4 and a faint tail 1'.5 long in p.a. 80 deg.

     2010 UT             R.A. (2000) Decl.       Mag.   Observer
     Jan.  8.09596    1 44 01.92   + 8 13 15.6   17.3   Hill

The available astrometry, the following preliminary parabolic
orbital elements, and an ephemeris appear on MPEC 2010-A48.

     T = 2010 Mar. 27.292 TT          Peri. =  38.455
                                      Node  =  63.847   2000.0
     q = 1.65798 AU                   Incl. =  15.064


COMET 217P/2009 F3 (LINEAR)
     Visual total-magnitude estimates by M. Goiato (Aracatuba,
Brazil, 22-cm reflector):  Nov. 13.12 UT, 10.6; Dec. 6.06, 10.9:;
18.21, 12.1.

                      (C) Copyright 2010 CBAT
2010 January 9                 (9106)            Daniel W. E. Green