Archival HST data of the SN field, where the F435W, F555W, F658N 
and F814W data were originally discussed by ATELs #3399/3401 (Li et al. 2011)
and we have added the WFPC2/F336W panel.  Note how the candidate
progenitor vanishes in the UV compared to the blue star to the North-East. The
panels are 4 arcsec square and the circle is 0.3 arcsec in radius.
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<IMG width=1000  align=center SRC="HST_all2.jpg">

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The residuals after using difference imaging to subtract the
F555W reference image from the F435W, F658N and F814W images.
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<IMG width=1000 align=center SRC="f555w_convs.jpg">

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The residuals after using difference imaging to subtract the
F814W reference image from the F435W, F555W and F658N images.
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<IMG width=1000 align=center SRC="f814w_convs.jpg">

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The original F658N image and the average of the F55W and F814W
subtracted images.  The presence of a positive residual in the
F658N band independent of whether the bluer F555W or redder
F814W filter is used as the subtraction template suggests that
it is an Halpha source.  Also note the faint, redder star 
blended with the candidate progenitor just to the South and
that its F658N residual shifts sign depending on the wavelength
of the reference image.
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<IMG width=1000 align=center SRC="f658n_conv.jpg">

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The SED of the progenitor including the Spitzer limits.  The
progenitor is modeled simply as a 7000K, 1.3e5 Lsun black
body with a shell of circumstellar dust producing 0.2 mag 
of extinction at an inner edge dust temperature of 500K.
A more realistic SED in this temperature regime would have
a Balmer break producing a lower UV flux.
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<IMG width=574 height=574 align=center SRC="prog.jpg">