read_objmask

I wrote a code to read objmask info for SDSS objects from the fpatlas files. This came down to modifying the atlas reading code to get multiple objects and copy their objmask info into an output structure. I then linked this to IDL using the DLM mechanism.

I was motivated to do this because we are going to start working on intracluster light in the MaxBCG and Percolation clusters. This gives a first look at the area associated with each object in a frame, which we will need to mask out in order to measure just the ICL. We will probably use a different area once we decide on the best masking algorithm.

Erin

30 Mpc M/L

Today I started a bunch of jobs on the computubg cluster here "mafalda" here at NYU. These should take a few days to finish, and I'll run another set after that. These are the last of the jobs for calculating the light and number densities of galaxies around the MaxBCG clusters. I had these to 10Mpc but now I'll have them to 30Mpc along with the lensing masses, so I'll have M/L over that entire range. If things look good I'll start writing that paper in a week or so.

Erin

Change of plans

Sarah Hansen and I are going to combine our papers on MaxBCG cluster-galaxy cross correlations with Sarah as first author. I have written up the method, described the selection etc., and made a bunch of plots. Risa didn't like that there was so much overlap between the two papers. I think she is probably right. Sarah is going to merge the sections from my paper into hers.

Erin

Switching to svn

My CVS archive at UChicago is no longer available, so I talked to the sysadmin here at NYU and we set up an SVN repository for all the code. This is actually kind of important. SVN makes managing code across many different machines and many different developers simple, more simply than CVS. And I feel like I have a good shot at keeping it available for a long time here unlike at Chicago. It will be easier to move now if needed too.

The Aspen meeting is next week and the SDSS cluster folk are going to be there in nearly full force. The SZ cluster people will be there too so we may here some news from SZA.

Wanted Distractions

Decided to put aside the cluster correlations and work on accessing a database through the web using Python. Over the break I put my Mom's recipes into a database web applicatioin using python. I looked into doing something like that with a larger data set, it is as straighforward as it sounds. The only trick will be convincing the sysadmin that it is secure enough.

There has been an exchange in the cluster group about how to model the lensing signal. It has become clear that mis-centering of cluster sample relative to the mass could be a real interpretational issue. Any mis-centering is basically degenerate with the halo concentration. Eduardo Rozo and Dave Johnston have ideas on how to constrain the mis-centering outside of the lensing signal to break the degeneracy.

I think this centering issue could severely limit the usefullness of the M/L measurements on halo scales. We can only account for the mis-centering with modeling, but we don't want to assume a form for the light distribution, certainly not NFW. One of the points is to see how different the profiles are in mass and light. On the other hand, if we can constain the mis-centering outside of these measurements the very high S/N light measurements could be recovered non-parametrically.

Erin