Thursday, June 11, 2009

Comparison with 2006 DAOphot parameter files

I compared the input parameter files to DAOphot that I used to the ones used for the 2006 paper.

In daophot.opt:
Most of it was similar. But the readout noise and gain were pretty significantly different. For the paper, noise=1.875 and gain=3.2 while I have noise=2.71 and gain=2.07. According to the website where I got my info, the 2006 gain is way out of whack ( unless I'm looking at the wrong info. According to that website I think my noise also makes sense but I might be wrong about the conversion. I know Beth has mentally sanity-checked it several times before.

I also have a variable psf of 2 compared to variable psf of 0. This means I'm considering a quadratic fit while the 2006 paper used a gaussian fit. I think if anything, mine will be better.

I have a larger psf radius--20 as compared to 11 used in 2006. These are certainly different but mine is set to be larger than the largest star. So I'm thinking they either should be different because my data has been stacked and/or mine will be better because 11 might just be too small.

In 2006, the default percent errors were while I set those to 0. I consulted Dave about this who also uses 0, though no one seems to know exactly how these work.

In allstar.opt

In 2006 Beth used the default inner and outer sky of 3 and 25, respectively. But I used 30 and 50. According to talking with Beth in the past, mine are legit. But it does concern me that these cover completely different ranges.

Again, the 2006 paper used default values for error while I have 0 for both.

In photo.opt
The paper used mostly default values in this file--apertures increasing in increments of 1. It used inner and outer sky to be 15 and 25. However, I use apertures that increase in increments of 2 and an inner and outer sky of 2 and 30. I'm thinking this is okay--I'm just being more liberal in my limits of sky and aperture. Though I don't know much about this file or where it came from, so I haven't spent too long thinking about proper values--before I started running DAOphot this summer Beth and I just glanced at this and assumed everything was about right. I am confused about why the inner and outer sky limits are not the same as those used in allstar.opt. In 2006 they weren't consistent, either.

No comments:

Post a Comment