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.

The residuals after using difference imaging to subtract the F555W reference image from the F435W, F658N and F814W images.

The residuals after using difference imaging to subtract the F814W reference image from the F435W, F555W and F658N images.

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.

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.