Friday, June 18, 2010

Distance and Completeness Updates

Today started out with breakfast in Zubrow for all the KINSC students. Twas good. It's also pot luck day!

I spent part of the afternoon helping some other folks figure things out. But now for my own work:

I came back and double checked my input to the distance code, just to be sure that everything was good to go there. I checked my technique against Dave's description of his calculation and went back to Shane's Bootes II paper, which Dave had cited. I discovered that there were a few additional things that I hadn't coded yet. Primarily, after I select the best fit isochrone or fiducial and the best distance, I need to bootstrap the distance calculation with the best fit to derive the error in the distance. Everything besides this last step is set, so I'll add the bootstrap after I've got the completeness stuff figured out.

I also tracked down the info about M13 and M92 (age/metallicity/distance) which was missing from yesterday's post.

I spent all afternoon working on the completeness calculation for the actual ASTs. I really want to get the full-fledged Allframing started before the weekend. At this point I need the results to make significant progress on other calculations. Essentially, a lot of things will come together quickly once the artificial star tests are finished and the completeness levels are calculated.

Last I left the completeness calculation, I had a debugged version for the bright star tests, but had run into trouble matching the positions for the real test. That problem is still there. I did find a bug in the code where I was creating the input addstar file, so I made new ones and am running Allframe again. Hopefully that will solve the problem. In the meantime, I'm going to double check a few other things. Fingers crossed, this will not be an issue by lunchtime. Below are some signs of problems I've discovered on my hunt for answers. These are results from the bad addstar input runs, so I'll go back after running Allframe again to see if these red flags are still there.

A few observations:
1. I'm definitely getting 96% completeness for the bright star tests at r < 22.5. I've confirmed qualitatively and quantitatively.
2. Without applying a faint magnitude limit, only 6 stars out of 1765 artificial stars are matching between my art star input and the output from Allframe.
3. There are fewer stars coming out of allframe for the true distribution than are getting input as artificial. This could possibly be correct but seems unlikely. Allframe will pick up noise down to 27.5 mags, so even for stuff that's very faint I should be getting a lot of signal there. This is not to mention the true stars that allframe should be picking out of the image, too.
4. A quick, informal survey of 22 stars in the center of the ref frame shows that 3/22 visible artstars weren't subtracted (at least not well) by DAOphot/Allstar. Real stars are getting subtracted pretty well.
5. The bright star test outputs 1426 more stars than the real artificial star test. After calibration the bright star masterlist contains 1538 more stars than the actual art star masterlist. After final chi/sharp cuts, the margin is almost twice as many stars in the bright masterlist as in the actual AST masterlist.
6. I've double checked my option files, the program I use to create the masterlist, and the calibration program and they're exactly the same for both the bright tests and the actual tests.

1. Paper revisions
2. Completeness calculation
3. Allframing

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