Monday, March 15, 2010

Artificial Star Tests and Max Likelihood

Artificial Star testing is about to get underway in earnest. My fake CMD is finally complete and I'm happy with the result. Now I'll choose how many stars to run per chip, based on a reasonable grid density. Then I'll begin running DAOphot and Allstar.

The max Likelihood results are looking decent down to a magnitude of 24.25. I'm working with a field with radius 10' about Martin et al's "center" of Willman 1. Going to 24.5th or 25th magnitude results in outrageous values for PA and, at 25th mag, even the ellipticity and rhalf are out of whack. These are with the strictest chi/sharp cuts I've made yet. They are:

-0.21 < sharp < 0.1
0.8 < chi < 1.21

The number of stars I'm inputting into the ML code with these chi/sharp cuts and a 10' radius field are:
23 mag: 502 (looks great!)
24 mag: 1095 (looks great!)
25 mag: 2405 (looks awful!)