Wednesday, August 12, 2009

Tools of the Trade

I've found some useful tools for blog writing when you are trying to insert equations and images.

I talked with Eric Gawiser today. He has thought a bit about the Newman method and had some good suggestions for me. He suggested that we would expect bias to be a function of redshift in the Sloan data set, and therefore we would have trouble properly normalizing our reconstruction because it would be the actual redshift distribution convolved with the bias function. He said that perhaps we could get a handle on the bias as a function of redshift by doing a 3D-autocorrelation function on the photometric data. I am not sure if this is already taken into account with the reconstruction or if the reconstruction is assuming a constant bias over redshift bins. This is something I need to talk to Alexia about. Nonetheless, Eric seems to know a lot about this and would be a good person to keep talking to about it.


I talked to David about the SVM-Light package. He seemed not so enthused. He said he wanted me to work out some other problems before I moved on to "code optimization." We went over how they ended up doing the selection on the QSOs using the likelihood method. He wants me to work out the normalization of the likelihood function so that the numbers actually mean something logical. He also isn't convinced that the MMT data is actually what we think it is. Apparently the method was only 75% complete with a 40% efficiency, so that isn't good. He wants me to get to the bottom of this and see if the QSO objects in the MMT data are actually quasars by comparing with Robert daSilva's variability catalogues. He also wants to check how good the method works on single-epoch data (they were running it on the co-added photometry).

He suggested that perhaps I run Michael Blanton's photo-z code on the Stripe-82 co-adds and use that at my data set for the Newman project. He suspects the photo-z's will be better than the single epoch data. He also suggested that perhaps a reason why my 3D correlation functions look so weird is because we get fiber collisions which wipe out correlations and ~Mpc scales (depending on redshift). Another reason to perhaps try this on mock data before I debug for years trying to find an error in my code (it's possible this method just wont work on this data set).


I gave the link to this blog to Alexia, and posted it on Facebook. I am fulfilling the whole "being accountable to people" rule. I guess I should change the blog's privacy settings so it is Google-able [DONE], and perhaps should add a link to my webpage. I hate the idea of people actually reading this (not that I think I am that important).

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