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IAUC 8992: Poss. REDDENED SNe IN NGC 972, NGC 5900; C/2006 OF_2

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                                                  Circular No. 8992
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://www.cfa.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

     C. C. Dudley and J. Fischer, Naval Research Laboratory, report
the discovery of two possible high-extinction supernovae in images
obtained with the U.S. Naval Observatory 1.55-m telescope (+ 2.1-
micron K' filter + ASTROCAM 1024x1024 ALADDIN InSb imager) at
Flagstaff (discovery observations tabulated below, with discovery
dates and approximate K' magnitudes at time of discovery).

PSN       Date (UT)          R.A. (2000.0) Decl.         K'    Offset
K0210-1   2002 Oct. 16.3   2h34m13s.34  +29o18'36".2    14.7   5" S
K0304-1   2003 Apr. 17.4   15 15 06.97  +42 12 19.3     17.7   20" E, 17" S

Additional approximate K' magnitudes for PSN K0210-1 in NGC 972:
2002 July 26.5 UT, [17.5 (3 sigma); Nov. 26.3 UT, 15.7; 2003 Jan.
13.1, 16.8 (3 sigma).  W. Li, University of California, infers that
examination of KAIT images during 2002 Sept. 5-Dec. 3 shows nothing
obvious at the position of K0210-1 (though there may have been a
very faint optical transient visible during that time located about
16".2 west and 19".5 north of the nucleus of NGC 972).  Additional
approximate K' magnitudes for PSN K0304-1 in NGC 5900:  2003 May
17.3, 17.9.  Li adds that there is no obvious optical transient at
the position of K0304-1 in KAIT images taken between 2003 Mar. 5
and July 5 (limiting mag about 21.0).
     It is estimated that PSN K0210-1 was first detected no more
than 60 days past maximum light and so was never brighter than K' =
13.4, assuming an average fading of 0.02 mag/day from Mattila and
Meikle (2001, MNRAS 342, 325, Table 5); it is anticipated that
K0210-1 experienced about 1 mag of extinction in K'.  If the
limiting mag is 21 near the nucleus in the optical for PSN K0210-1,
then these observations suggest about 6 mag of visual extinction or
greater toward the infrared object.  Assuming that both K0210-1 and
K0304-1 have the intrinsic colors of A-type stars, a limiting mag
of 21 in the optical suggests at least 3 magnitudes of visual
extinction for the source in NGC 5900; for a late-time observation,
the source could be intrinsically much redder, requiring less or no
extinction.  Additional optical observations within a few months of
the above observations would be useful to help to set limits on the
extinction of each object.

     Visual total-mag estimates by J. J. Gonzalez, Leon, Spain
(20-cm reflector):  June 28.02 UT, 11.9; Aug. 9.06, 10.8; Sept.
6.98, 9.9; 29.15, 10.0.

                      (C) Copyright 2008 CBAT
2008 October 6                 (8992)            Daniel W. E. Green

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