Stacking comet subs (guided on nucleus)

[mstriebeck]

Hi,

I took some images of Lovejoy and guided on the comet nucleus. I timed the subs such that the stars don't overlap from one exposure to the next. I was hoping that through that, I could remove the stars more or less completely with pixel rejection and get an image of only the comet. But regardless of what I try, I always get some star trails which are almost as bright as the tail - which makes it impossible for me to process it.

The images are here: https://drive.google.com/folderview?id=0B0KcEqw-v71VbG5iWTdvM1VNaEE&usp=sharing

Any help or ideas are appreciated!

     MarkS

[pfile]

i think what's going on is the normalization in ImageIntegration is getting thrown off by the gradient in the image. bad normalization for whatever reason == II has a hard time knowing what is truly an outlier across all the images.

i only stacked your blue "2" files, but first i opened them all and did a LinearFit with image 1 as the reference, then saved them. then in imageIntegration, i turned off normalization for both the stacking and rejection.

i suspect if you flattened these images the result might be better without the LF, but i'm not totally sure of that. another approach would be to DBE the images before going into II, but flats would be better.

 anyway the result is better, but still not perfect. maybe it would improve if i threw in the "1" images as well.

rob