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- Measure equivalent widths of the six features, analyze over time
- My analysis so far has only been on a subset of all the data, due to the difficulty of not having access to the external drive on my mac. To do: get another external drive to reformat the original drive, allowing me to analyze all the data at once
- Cosmic rays may throw off the way my code analyzes the images. Matt recommended I use cosmics.py to simply remove them from the image before analysis.
- Temperature data is stored in the headers of the files. Investigate how the quality of the image changes versus time or temperature (e.g. focal length)
Update 25 Jan 2015, Tyler St. Germaine
Cosmics.py does not work well with slitless spectrograph images
Cosmics.py is a python module based on the LA Cosmic algorithm. I downloaded it from here. It just looks for hot pixels and throws them out, while making sure saturated stars do not get thrown out.
Perhaps predictably it does not work well with these images, where the objects are dispersed over many pixels. Example:
It's a little hard to see, but some pixels within the Polaris spectrum are removed entirely, which obviously throws off the analysis.
Fitting the continuum
I use the python class LSQUnivaraiteSpline to fit a spline to the continuum of the spectrum. The knots are controlled manually so that they do not lie on the absorption features (right now they only avoid the six features described above, but I should in the future add more features to avoid such as those near 625 and 650 nm). This continuum is then divided out to give extinction vs wavelength.