CBET 1265 POSSIBLE REBRIGHTENING OF 2005md IN NGC 2274
W. Li, A. V. Filippenko, R. Mostardi, R. Chornock, R. J. Foley, and
N. Smith, University of California at Berkeley, report the discovery of
either a new supernova within 0".5 of 2005md (IAUC 8647), or a rebrightening
of 2005md. KAIT images taken via the Lick Observatory Supernova Search on
Feb. 11-13 UT show an object (at mag 18.5) at R.A. = 6h47m19s.10, Decl. =
+33o34'24".5 (equinox 2000.0), which is 21".7 east and 23".1 north of the
nucleus of NGC 2274. This position differs from the reported position of
2005md by 0".1 in R.A. and 0".4 in Decl; 2005md was discovered on 2005 Dec.
25.35 at mag 18.1 (CBET 332) and was classified as a possible young type-II
supernova by Modjaz et al. (IAUC 8650). However, the reported spectrum only
showed a featureless blue continuum, with no obvious broad supernova features.
KAIT images of 2005md also showed that the object declined quickly, and it was
fainter than mag 19.8 in 2006 January. A combined image of the field taken
with KAIT during the year 2007 shows no obvious object to a limiting magnitude
of 20.7. At the distance of NGC 2274 (about 70 Mpc), 0".5 corresponds to a
linear distance of about 120 pc, so it is possible that the object detected in
the 2008 Feb. images is a new supernova very close in position to 2005md and
that the two objects are unrelated. However, if the new object is a
rebrightening of 2005md, a possible explanation is that detections made in
2005 Dec. and 2008 Feb. are the super-outbursts of a luminous blue variable
(LBV), or multiple flares of the LBV as part of an extended eruption. Other
possible explanations are a Galactic variable star or a background AGN/blazar.
Observations of this object are encouraged.
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
2008 February 18 (CBET 1265) Daniel W. E. Green
