The Iris Nebula

[Davide Simonetti]

The Iris Nebula captured from London on July 3rd 2015. 

This image is another test of guiding telescope capabilities, this time with a more challenging target and longer exposures. Over 8 minutes a small amount of movement was detectable but I'm hoping it may be possible to reduce that further.

10 x 8 minute exposures at 400 ISO

 3 x dark frames

 5 x flat frames

21 x bias/offset frames (applied to flat frames only)

Processed in Nebulosity and Photoshop

[kalasinman]

David, I hope some advise ok. Use more darks, at least as many as flats. Dither at least 15 pixels every  frame (important). In DSS go to settings, stacking settings, lights and tick Kappa-Sigma clipping. This will remove outliers such as gamma rays, satellites, and even clean up stars a tiny bit. I believe you need 30 lights for it to be effective. Your exposure looks good, but not nearly enough data. With a ton more data, the lovely color you have will come out.

[Davide Simonetti]

David, I hope some advise ok. Use more darks, at least as many as flats. Dither at least 15 pixels every  frame (important). In DSS go to settings, stacking settings, lights and tick Kappa-Sigma clipping. This will remove outliers such as gamma rays, satellites, and even clean up stars a tiny bit. I believe you need 30 lights for it to be effective. Your exposure looks good, but not nearly enough data. With a ton more data, the lovely color you have will come out.

Thanks very much for the advice. I think you're right, this does need more exposure. I can add data to this but I stopped last night as it was starting to get light and I only had time to take a few darks...I will take some more though. I use Nebulosity for processing (I find it better than DSS although it's more laborious) and it also has a filter for removing anomalies, which I applied. The image came out quite dark though and when I stretched the histogram a lot of gradient and light pollution showed up so this is a bit of a compromise. The main purpose of this shot was to test guiding which is something I'm very new to and still learning. At 8 minutes per exposure there was some movement which I hope I can reduce next time.

[kalasinman]

Indeed. I'm focussed on the sdame issues here. I expect this year will be more about improving the kit and the methods than a body of images. I am aiming for the early winter season to rally get going.