don't co-add your data!

Lang showed today that there is no sensible co-addition of imaging data that permits the detection of sources as well as estimating significance jointly in the not co-added images. The best formulation of this is to create not a co-add, but a significance map that maps out on the sky the likelihood of a source as a function of position. The combination of these significance maps is non trivial—it is not simple signal-to-noise-squared weighting of signal-to-noise maps—but it is tractable and no harder than most current co-adding schemes. Now we will sell this technology to any survey team in exchange for the fraction of observing time or operating cash we save them!


  1. This basic concept is actually already embedded in the heart of the DOLPHOT package for crowded field stellar photometry!

  2. What model do you use for the source profile, and how do you integrate over its parameters?