Wednesday, December 9, 2009

Allframe is now finished and I have a master list. Unfortunately, there are some problems on chip2 which are not looking good. I still haven't figured out a way to work around this; it appears as though there's a steep gradient on the outside of the chip where the number of stars drops off dramatically. I had difficulty allstar'ing a few exposures, but neither was on chip2 and that doesn't appear to have made a difference, though it will show up during the ASTs if there is a difference. I'm re-allstarring and will re-allframe just in case this could change something. The only anomaly I've found with chip2 is the fact that daomaster found a larger number of stars than on the other chips. However, the chip2 .als files contain a proper number of stars and the astrometry appears to be just fine, so I don't know what exactly in the allstar-ing could have been wrong.

I double checked the position of stars in the allstar file of every individual exposure on chip2 and didn't see the gradient in any of them, so it must be some weird aggregate affect which is concerning. I found that rchip2_179_nast.als appeared to have a higher density of stars which was strange, but no gradient. I'm stumped.

I moved forward anyway and did some cuts in chi and sharp cuts. My masterlist started out with 117,137 stars and after the cuts it's left with 54,137 stars. In lieu of a solution to the problems with chip2 I'm going to use this latter master list (after cuts) to move forward with calibrations.

Before I spend too much time on that, I imagine I should be working on simulating a perfect ellipse for my AAS poster which needs to be completed before next Friday...

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