weak lensing

I had two telecons today. The first was with Phil Marshall, to discuss my Atlas project, which needs some love and attention. Phil had lots of good ideas for improvements that make it more fun and more useful. In the second I joined a meeting with Marshall's GREAT3 team, which is getting ready to compete in the upcoming weak lensing competition. The team includes Lang, who is operating the farm machinery required. We discussed the importance of having an explicit (and good) prior over galaxy shapes, something that team members Schneider (LLNL) and Dawson (LLNL) are working on at the theory level. We also discussed how to parameterize ellipticity. My position is: If you are working at catalog level (which might be a mistake), you want to work with the point estimates (catalog entries) that are closest to having a Gaussian likelihood! This, if you trace it down, ends up being a statement about ellipticity parameterization. All that said, I expect that all methods working at catalog level are (in the end) doomed to failure. The only things I can see working at catalog level are actually more computationally intensive than working at image (pixel) level.

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