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Satellite and asteroid trail help
I have another issue with satellite trails (plus asteroids this time too). This one is perplexing to me and you'll see why soon. I have started a two panel mosaic of NGC 1333 & vdB 16. This is of course an area near the asteroid belt so there are a lot, but also satellites.
See my image on the left, which was a single panel integration - asteroid trails are there still but no satellites. I used the settings of LN MAD Winsor Clip - Kappa 3 - Iterations 1 for the single panel.
On the right is my two panel mosaic - now we have both asteroids and satellites. Having seen these asteroid trails in the single pane integration I figured I ought to increase the aggressiveness for the mosaic and used LN MAD Winsor Clip - Kappa 2.5 - Iterations 2.
This is baffling to me because there have been no frames added to this except the ones below it for the mosaic. What am I doing wrong here? Should I use LN MAD Sigma Clip, change the kappa or iterations? These satellites are driving me nuts! I have another integration with geostationary sats on a target near Orion which is also having a problem getting them rejected. Each panel is 210 frames. I really don't want to spend another 36 hour integration wait more than once again so hoping to get it right on the next one before running. Thanks.
Sigma clipping should be able to take care of those for sure. Maybe you could upload a few frames for me to try out? Like 10?
Yes I can do that later. Tried again with another integration with the settings more aggressive, Kappa 2.0 and iterations 3. It is somehow worse. I am using the diffraction protection set to 5. Could using this cause issues?
That is really odd, with that many frames it should be fairly easy to reject even with less aggressive settings. Unless maybe this region is so bad it becomes too tricky somehow, would love seeing that myself in the data. I don't think diffraction protection would prevent that, that's meant for the borders of stars mainly.
So I have gotten a good result finally with the satellite trails (still have yet to run something on the one above with asteroids). I had to disable diffraction protection (I had it set to 5 pixels). Perhaps some note should be made somewhere in the documentation that this can cause problems with trail rejection? I tried lowering kappa very low, increased iterations to 5, and nothing worked. I could find nothing else that worked besides disabling diffraction protection.
Here are the rejection maps for each. I believe the file names should give the settings info but if not the dark one is kappa 2.0, iterations 5, and diffraction protection 5. The green one that rejected trails is kappa 2.5, iterations 3, diffraction protection none. I am running another now to see if I can get the kappa back to the standard 3.0 and iterations lowered to 2 to avoid rejecting more data than I need to.
That is very interesting @jtrezzo thanks for sharing. I never had this particular problem with that option selected. Good to keep in mind then.