[IAUC] IAUC 8772: COMET C/2006 M4 (SWAN); C/2006 R3, C/2006 R4, C/2006 S7-S9 [25139-2007/05-R1]

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                                                  Circular No. 8772
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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COMET C/2006 M4 (SWAN)
     C. E. Woodward and M. S. Kelley, University of Minnesota; and
P. M. Hinz, M. A. Kenworthy, and W. F. Hoffman, Steward Observatory,
University of Arizona, report the discovery, in 10.55-micron narrow-
band (FWHM = 0.97 micron) images obtained with the 6.5-m MMT
telescope (+ MIRAC4-BLINC) and adaptive optics (AO) secondary on
Nov. 7.08 UT, of a detached-coma feature located 3".4 from the
nuclear condensation of comet C/2006 M4 (corresponding to 2700 km
at a geocentric distance of 1.10 AU) in p.a. approximately 43 deg.
Aperture photometry, derived from images obtained through thin
cirrus, with the AO system locked on the diffuse comet nucleus in a
3".1 circular beam, yields 10.55-micron fluxes of 9.5 +/- 0.5 Jy for
the nuclear condensation and 4.1 +/- 0.4 Jy for the detached-coma
feature.  The detached-coma feature is elongated along the same
position angle, with a spatial extent of approximately 3" by 1".5.
The nucleus was unresolved in the diffraction-limited images (FWHM
= 0".4) and appears to be embedded in a diffuse coma (FWHM = 0".7).
Further mid-infrared observations are encouraged.


COMETS C/2006 R3, C/2006 R4, C/2006 S7-S9 (SOHO)
     Several additional apparent comets have been found on SOHO
website images (cf. IAUC 8740), all being Kreutz sungrazers except
for C/2006 R3 (Meyer group), which was very small, stellar in
appearance, elongated, and of mag about 7.5.  K. Battams notes that
C/2006 R4 was mostly stellar in appearance with a hint of tail,
reaching mag about 3.5.  C/2006 S7 shows a hint of tail and was
mostly stellar in appearance (mag about 5) in C3 images, while in
C2 images it appeared very diffuse and quite faint.  C/2006 S8 was
slightly elongated and reached mag about 4.5 in C3 images; in C2
images, it was somewhat diffuse with a hint of tail, and it faded
quite rapidly.  C/2006 S9 appeared stellar with a hint of
elongation (mag about 6) in C3 images; in C2 images, it was diffuse
with a hint of tail and quite faint.

Comet        2006 UT       R.A.(2000)Decl.   Inst.  F    MPEC
C/2006 R3    Sept. 2.675  10 42.6   + 9 38   C2     HS   2006-U63
C/2006 R4         11.746  10 53.9   + 3 18   C3     TH   2006-U63
C/2006 S7         18.138  11 20.8   + 0 52   C3/2   RM   2006-U63
C/2006 S8         18.488  11 22.4   - 0 03   C3/2   RM   2006-U63
C/2006 S9         18.488  11 27.3   + 0 54   C3/2   RM   2006-U63

                      (C) Copyright 2006 CBAT
2006 November 11               (8772)            Daniel W. E. Green