Tuesday, June 8, 2010

Completeness problem found!

I was still having completeness problems up until group meeting this afternoon. So Beth gave me some suggestions to sanity check things in more detail. I went back to the image files of the original data, artificial star data, and art star-subtracted data. Turns out half of the stars I was inputting weren't showing up. I looked for stars brighter than 21.5 mag and wasn't finding most of them. So, again at Beth's suggestion, I created a new .add file of artificial stars that all had a magnitude of 20 (clearly bright enough to see by eye). When I ran this file through DAOphot, Addstar, and Allstar, every other row of artificial stars were missing. That would explain at least in part why I wasn't finding many artificial stars.

This is more or less taking me back to square one but that's a good thing in this case. I need to take a look at how I'm running addstar and see if there's an obvious solution. Otherwise I think I could just troubleshoot the problem by putting in twice as many stars with half the spacing in the vertical direction (to get the originally intended effect). Then before calculating completeness I'll just need to create a .add file with the artificial stars that actually appear in the output of addstar.

Making the addstar fix is next on the agenda and will hopefully alleviate all of my problems, but we'll see. I'm also still going to check the aperture photometry on a few of the stars in the artificial images to be sure that the photometry is looking sane. I'll check both the bright grid and the one generated from the fake CMD.

Tomorrow is AstroPhilly! So I won't be doing much of this tomorrow, but I'll be back to it on Thursday.

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