digital galaxy atlas

On Monday, I rewarded myself for weeks of work on that NSF proposal with a day of work on my digital galaxy atlas project. I worked on two things, both pretty technical:

I worked on the problem of producing, for each galaxy image, a noise map that gives approximately the correct pixel-to-pixel noise or uncertainty in the intensity. This is relatively trivial, in that we have a noise model (even an implemented noise model), but it requires some decisions (a) where I have smoothed the data either explicitly or implicitly, and (b) where overlapping fields contribute to the image.

I also worked on automatic identification, fitting, and subtraction of all satellite trails in the images. For this project I am using a Hough transform, in which the space of x and y (pixels in the original image) gets transformed into the space of angle and offset for linear trails (each of these is a pixel in the Hough transform image). I think I need to do some kind of median filtering because in the dumbest possible implemetation (recall that I always start with this!) pairs and triples of stars dominate the signal.