Thursday, July 22, 2010

Double Rainbow

Things are moving smoothly here in Wil1 land. I made some important progress today.

Photometric Uncertainty: After a bit of debugging I have the photometric uncertainty as a function of magnitude from the artificial star tests. I've been using it all over the place--to calculate the distance and the morphology of Wil1. 

Distance: The official new distance calculation has been finalized. The distance to Wil1 is 36 kpc which corresponds to a distance modulus of 17.781. The prize for best fit main sequence goes to M92. My tentative distance uncertainty is 1kpc, but as Beth pointed out we need to adjust this based on the best fit distances of runner-up main sequence candidates.

Morphology: With the new distance modulus and fiducial in hand I updated the spatial density plot of Wil1. I also updated the code to include a color-cut based on an envelope derived from the photometric error which I calculated yesterday and finalized this morning. It already looked better with the 15 sigma contour back in action. I'm using a larger field now than I was in May (14'x14' as opposed to 10'x10'). I compared several smoothing lengths between 0.3' and 0.6'. The choice is rather arbitrary as to which to use at this point. I think 0.5' or 0.6' give the least noise, but all of the smoothing lengths demonstrate essentially the same features and irregularity with varying degrees of noise. I'm going to run with the 0.6' smoothing for the sake of a paper draft.

Simulation: Beth is going to send me the debugged simulation code she worked so hard on so I can compare the real results to a simulation of the same number of stars. That means digging out the number of stars as output by the ML code. Once the simulated positions are made it's just a matter of putting them through the plotting routine to create the same spatial plots for comparison.


Things have been going well as far as progress is concerned. Results are coming together quickly, as expected. Tomorrow I need to calculate uncertainties on the structural params from the ML results and the distance. I'll also spend a fair amount of time adding the results I have to the paper which I haven't touched in a while. My main goal for tomorrow is to tie up loose ends and get real numbers into the paper. When that's all done I'll move on to wrapping up the simulation analysis and completing the last few calculations--absolute magnitude and surface brightness and the tidal radius what-ifs. By this time next week there will definitely be a paper draft.

Aside from wrapping up calculations and paper writing, next week will be all about documentation and cleaning up my directories.

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