C/2010 S1 Linear in Collinder 399 (Coathanger)

[timtrice]

On Sep. 21, 2013 Comet Linear passed roughly 2' west of Collinder 399. As it was cloudy, I was unable to capture this until days later. Comet Linear was captured with 65 lights, no bias/darks/flats. Collinder 399 was captured a couple of evenings later. As my scope/camera combo could not capture the entire asterism, I split the false cluster in two capturing the western portion in 31 60-second exposures, iso 500 followed by 20 60-second exposures of the eastern portion. 

Collinder 399 was calibrated with 38 bias, 19 darks and flats.

Camera was a Canon 60D. Scope is a 10" Orion Astrograph on an iOptron IEQ45 (GEM). 

Images were captured using Backyard EOS and processed largely in PixInsight  with minor edits in Photoshop CS3. 

I did not record seeing/transparency though it would've been in the middle ranges. Captured from an orange zone.

The biggest issue I had was with the comet and extracting the comet and what I felt was a tail from the star trail left from the comet alignment. However, I did a ACDNR tool putting a heavy mask on the comet and trying to blur out the rest. When I realized I couldn't save the tail, I moved the image to Photoshop and did a select and feather around the coma and deleted the inverse. The comet appears much brighter than what it would have appeared if photographed at the time  as I have much more lights but I really wanted to try to pull the nucleus out which I think I did rather well. I may go back and try to get a more natural look later on.

The mosaic with Collinder 399 I felt was equally as difficult. I had completley forgotten to go back and capture my darks/flats and had started processing right away. As I had never used the Star Alignment tool in mosaic form as well as the PixelMath tool, I had to continuously reset. After agonizing hours later I saw the vignetting and did what I needed to do. Futhermore, I did not do any post processing prior to the mosaic alignment which hurt. 

After capturing my bias/darks/flats and doing some post processing, I was finally able to get a very good mosaic together. I did some additional cropping which sadly was necessary; I couldn't pick up a guide star when on the western edge thus had to crop much more than I wanted. 

All in all I'm very happy with how this came out. I wanted to do this in preparation for whatever Ison gives us and I felt this was a good opportunity to really put PI to use as well as learn the tools I'll need to learn. 

But I am also not a thin-skinned individual and want to learn more. So let me have it - what could I have done differently here?

Thanks for looking. 

[todd8137]

Very good i did a few last year you caught this well ,great image

Pat

[michael.h.f.wilkinson]

Nice one.

[WaveSoarer]

That's my very favourite asterism. A great image.