photometric redshifts

I spent the morning in two conversations about photometric redshifts, one with Buell Jannuzi (NOAO), who is using them to measure evolution of clustering of massive galaxies, and one with Alexandra Abate (Arizona), who is using them (and anything else she can find) to estimate the redshift distribution of weak-lensing galaxies in future LSST data. Abate and I figured out that extremely low signal-to-noise spectroscopy could in principle be very decisive, because for objects that have a wide range of redshifts permitted by photometric redshifts, there is usually a strong dependence of inferred redshift on inferred SED (and therefore predicted emission lines). I promised both Jannuzi and Abate that I would write notes on the airplane home.

In the afternoon, Mario Juric (NOAO) and I talked about all things LSST, including how we can go beyond catalogs to data products that contain more probabilistic and noise-model information. As my loyal reader knows, I think that if all LSST produces is a catalog and some images, it will not achieve many of its most valuable goals.