[IAUC] IAUC 9215: COMET C/2011 L4 (PANSTARRS); C/2009 Y16, C/2009 Y17 [25139-2011/04-R1]

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                                                  Circular No. 9215
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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CBATIAU en EPS.HARVARD.EDU           ISSN 0081-0304
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Prepared using the Tamkin Foundation Computer Network


COMET C/2011 L4 (PANSTARRS)
     Richard Wainscoat, Institute for Astronomy, University of
Hawaii, reports that an object discovered on four CCD images taken
with the 1.8-m "Pan-STARRS 1" telescope at Haleakala (discovery
observation tabulated below) appeared to show slight non-stellar
appearance; three follow-up 30-s r-band exposures were then
acquired by M. Micheli and Wainscoat with the Canada-France-Hawaii
Telescope on Mauna Kea (queue observer Lisa Wells) on June 7.44 UT,
showing that a coma is definitely visible with a subtle hint of a
faint tail towards p.a. 60 deg.  After posting on the Minor Planet
Center's 'NEOCP' webpage, other CCD astrometrists have commented on
the object's cometary appearance.  Images taken by R. Holmes
(Ashmore, IL, USA, 0.61-m astrograph; June 7.25-7.26), and measured
by S. Foglia and T. Vorobjov, show the object's profile to be 30
percent larger than those of nearby stars.  G. Sostero and E. Guido
write that fourteen stacked unfiltered 180-s images taken remotely
on June 7.4 with a 0.35-m reflector at the Tzec Maun Observatory
near Mayhill show the object to be slightly diffuse with a hint of
elongation toward the northeast.  H. Sato (Tokyo, Japan; remotely
using a 0.50-m reflector at the RAS Observatory near Mayhill, NM,
U.S.A.; June 8.3) finds a 6" coma of total red mag 18.5.

     2011 UT             R.A. (2000) Decl.       Mag.
     June  6.38910   16 10 41.08   -16 38 39.8   19.4

The available astrometry (including May 24 prediscovery observations
from Mt. Lemmon), the following preliminary parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2011-L33.

     T = 2013 Apr. 17.1236 TT         Peri. = 331.6636
                                      Node  =  64.2255  2000.0
     q = 0.364374 AU                  Incl. = 104.7422


COMETS C/2009 Y16 AND C/2009 Y17 (STEREO)
     Further to IAUC 9200, additional slightly diffuse Kreutz
sungrazers have been found on STEREO HI-1 website images.  Peak
approximate magnitudes:  C/2009 Y16, 10-11; C/2009 Y17, 10.

 Comet        2009 UT       R.A.(2000)Decl.   Inst.  F    MPEC
 C/2009 Y16   Dec. 30.183   23 19.8  - 8 23   HI-1   AW   2010-O31
 C/2009 Y17        30.711   23 22.2  - 7 50   HI-1   AW   2010-O31

                      (C) Copyright 2011 CBAT
2011 June 8                    (9215)            Daniel W. E. Green