Swift/UVOT photometry version 13.2

Swift has observed hundreds of supernovae over the last nine years, including dozens of very well sampled light curves published in many different papers (see post to Swift SN publication list here).  The calibration has been improved over the years, with the zeropoints of Poole et al. 2008 being updated in Breeveld et al. 2011.  As of 2010-11-30 these new zeropoints have been included in the Swift CALDB used with the HEASARC software (ie uvotsource and uvotmaghist).  A sensitivity loss of about 1% per year has also been discovered and is incorporated into the HEASARC software as of 2010-6-30.  Combining these effects could lead to a 0.1 magnitude error when comparing new and old photometry.

To allow an accurate comparison between new SNe and those published earlier in the mission, I have redone the photometry for using the latest calibration.  The photometry for the SNe Ia published in Brown et al. 2009 and 2012 have been redone and posted here.  The original references are given in the files, and I will be redoing other SNe as time allows.  I have also posted the reduction code here.  Please report any bugs, suspicious data, or deviations from ground photometry (for B and V, the Swift u band is quite different from ground-based u' or U) in the comments below or to uv dot supernova at gmail dot com.

A set of CC SN photometry from Pritchard et al. 2013 on the same system (but slightly different analysis) is posted here.

Notes:

The coincidence-loss saturation limit is currently set at 0.98 counts per frame.  This should be more rigorously tested.

There is something wrong with the three sigma upper limits, as the SN2006mr photometry lists magnitudes that are only 1-2 sigma detections.  I think the photometry is right, but there is an inconsistency in how the photometric errors are calculated and how the upper limits are calculated.  It might be the inclusion of the galaxy subtraction errors in the limit, as SN2006mr had the largest underlying galaxy count rate.