Simulations for Intracluster Light

I worked on simulating the ICL for our pipeline. This is just creating fake sersic profiles ala the measurements of Gonzales et al., so it should be straightforward. I found, however, that as with many things in astronomy I spent all my time just trying to figure out the units and conventions. There is the usual -2.5log crap for the surface brightness limits, but also the notation for Sersic profiles makes no sense. I wasted a lot of time thinking r_e really was the effective radius when people actually mean the half light radius.

In figuring all this out, I wrote pure IDL code for converting r0->r50 (roots of the incomplete gamma function) and making images of Sersic profiles. The images don't properly integrate over the pixels on small scales for large n, small r_e (in pixels) but they are fine for these purposes. I faked it by putting in a core.

P.S.
28 mags/arcsec^2 = 6.3e-3 nmgy/arcsec^2

P.P.S.
mags/arcsec^2 = worst unit ever

Photozs

Rachel and a student at Princeton are working on a lensing project using the MaxBCG clusters. We did some comparisons and saw considerable disagreement between the recovered signals. It turns out that during the last iteration of the photozs a bug was introduced that made the colors look really wrong and the photozs too high. This was not in their estimator, but a difference in magnitude systems between training set and my catalog. It was just a confusion of conventions, but of course those can have disturbing consequences

By the way, does anyone read this blog besides my mom?

Erin