Electronic Telegram No. 1180
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
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SUPERNOVA 2007sr IN NGC 4038
     M. Shimada and H. Yamaoka, Kyushu University, report that they have
compared the image of SN 2007sr taken by Naito et al. (cf. CBET 1173) on
Dec. 19.81 UT, using the NAYUTA 2.0-m telescope, with the archival images
taken at the 8.3-m Subaru telescope on 2004 Feb. 18.  On the Subaru V-band
image, there is no object within 1" of SN 2007sr, to magnitude 23.8 (3-sigma
limit); this indicates that, three years before the explosion, the precursor
of 2007sr was at M_B > -7.6, adopting the distance modulus of 31.41 (Zhang
et al. 2001, Ap.J. 561, 727).  Further investigation of archived images at
other wavelengths and with other instruments is in progress.
     Visual magnitude estimate by P. Schmeer, Bischmisheim, Germany (cf.
CBET 1174):  Dec. 21.227 UT, 12.8.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2007 CBAT
2007 December 24                 (CBET 1180)              Daniel W. E. Green