The photometry in neowiser was validated against the cryo and post-cryo epochs in turn, given we separated them for this exercise, i.e., instead of AllWISE which was a mix of cryo and post-cryo and used the same PSF templates for photometry throughout. To remind you, the W0855 multiframe run for neowiser used frames that were processed with a provisional set of calibrations and PSFs, so things were not optimal at the time.

I compared both w?mpro (profile fit) and w?mag_6 (=19.25” aperture) measurements. The reason for the latter was to minimize changes in the PSF (and hence biases from using fixed PSF templates) when going from cryo to neowiser. In general, the differences in w?mpro when going from cryo to post-cryo or to neowiser show a systematic trend with flux - evidence that the PSFs evolved. However, the differences in w?mag6 are flat (independent of flux) with an offset only between cryo and post-cryo. To my surprise, there is no offset between cryo and neowiser according to w?mag6. I.e., there’s no throughput change!

F. Masci, 5/16/2014