Eskimo Nebula attempt

[Jonathan Nicholls]

hi 

I've attempted to image the Eskimo Plantetery Nebula last week. i knew it would be a tricky one due to its apparent size, but i couldn't resist when i saw the blue blob through the eyepiece. The image in the link below is 144 light frames of 60seconds with darks and flat calibration frames,  I have some bad data as you can see my stars are not round dues to wind and bad (unguided) tracking,  zooming in on the nebula, the core is washed out and i wounder how to get more detail of that next time, I was using ISO 3200 60second frames so maybe need to use lower iso also to stop the core blowing out?

maybe also i need to add a barlow lens to help magnify the area since just cropping and zooming in on this reveals noise and lack of resolution. my DSLR is 16M pixel. I did use 2x drizzle when stacking this to try and get a better apparent resolution. what do you think i could do to improve this?

 

https://www.astrobin.com/full/0gvhy0/0/

 

 

[+RonC]

I think 60 secs is pushing it without any guiding, 30 secs and more subs might be a better solution?

Good start though.. 👍

[Clive]

Did you use Kappa Sigma stacking?  I've found that it can help 'round' the stars in the final image especially if the elongation and direction of the stars in the individual images is not identical.

[Jonathan Nicholls]

47 minutes ago, Clive said:

Did you use Kappa Sigma stacking?  I've found that it can help 'round' the stars in the final image especially if the elongation and direction of the stars in the individual images is not identical.

yes kappa sigma was used. some subs were perfect, others not so. so i got an average of round and elongated stars.  i have some periodic error in my drive which i have tried to correct with PEC, but still not perfect

[Bottletopburly]

Startools has a good algorithm for rounding stars .

[Clive]

You could try reducing the sigma variable so more of the 'outliers' will be rejected.

[Jonathan Nicholls]

1 minute ago, Clive said:

You could try reducing the sigma variable so more of the 'outliers' will be rejected.

good tip, will try that. it currently is kappa 2 iterations 5.  would i reduce kappa value or iterations?

[Clive]

Reducing the Kappa value should increase the number of outliners rejected.  The downside is that the resulting image noise may increase as less pixels are used for the stack (since I am able to guide and generally get round stars, it usually increase Kappa from 2 to 3. It reduces the final image noise and, providing you have sufficient subs, still removes satellites and planes)