Iris Nebula and a hello

[dodgeandburn]

Hello all,

I wanted to introduce myself a little bit and share with you a new image of mine.

I’m Sean. My wife and I moved to the area about 4 years ago. I’ve been involved in astronomy on and off since I was a kid. I’ve also been doing some kind of astrophotography on and off for the last 12 years or so, with my trusty Canon 20d with a long lens, and sometimes with a telescope. Only recently did I finally plop down the money on a better scope, mount and CCD camera.

I joined ASSNE early in 2016, but never posted anything. I didn’t get to do much imaging this year. My scope was being fixed for the first few months and… life, you know. I also attended the September Skies party in 2015 and probably met some of you. It was the first time I’ve gone to something like that and it was quite fun to look through all the different scopes.

Anyway, here’s an image that I captured in July and August this year. It was by far the hardest one I've done yet. It was very difficult to poke through the light pollution here.

[Bruce D]

Hi Sean, awesome image, and I scrolled through the other images in your online folder, you have some great stuff there!

[Pete]

Oh wow! We've got another accomplished imager in the club

Very nice indeed Sean.

Pete

[DonB]

Yes, Sean, these are supurb images. Very nicely done. Of coarse now we all want all the information. Scope, mount,camera,exposure,etc,etc. Totally cool !!

Don

[Chuck]

Hi Sean, welcome and great image of the Iris Nebula. Wow, 29.5 hours integration time. I'm assuming you didn't use an lps filter, is that right? What would you rate your light pollution zone to be? I'm in an orange zone myself, so I'm interested in all your acquisition details also. I love your all your images, especially that of Comet Lovejoy. I don't get much time to image myself, so I feel your pain. Thanks for sharing. ---- Chuck

[dodgeandburn]

Thanks for the warm welcome everyone. Sorry about not posting any details!

• William Optics Star71-II
• QSI 690 WSG-8
• Losmandy G11 Digital Drive

And the image is comprised of:

• 174 L frames @ 300 seconds
• 15 frames each RGB color @ 1200 seconds
• Processed in Pixinsight

This is actually my first LRGB image. I've attempted them before, but I wasn't happy with the results so I stuck to RGB-only for simplicity and reliability. However, while processing early versions of this image with only RGB frames, it became apparent I'm going to need some help with the dim, dusty areas and it seemed like good opportunity to give it another try. It was still a big challenge but it definitely helped after digging in and figuring out how to process LRGB better.

And Chuck, LPS filter, I believe the Luminance filter has an IR cutoff and the RGB filters have dips in their transmissions to exclude common light pollution wavelengths. So, in a way, yes I did. I'm on an Orange/Red border. In particular, my north is the most heavily light polluted part of the sky for me. On the best of nights I can barely make out the Milky Way overhead, and that's partly because I know what I'm looking for!

[Chuck]

Thanks for the info Sean. Myself, I'm basically just starting out and using a DSLR, unguided, at prime focus or piggybacked on my Meade C8 mounted on a Celestron AVX. My next step may be to move up to guiding, depending on the results of my next few targets. ----- Chuck

[AndyG]

Hi Sean,

Welcome to the forum, and thanks for posting that wonderful image. Outstanding job on the processing! It's really hard to process that dusty stuff and you totally nailed it.

I think there are a few of us in the club now who use PixInsight and it would be cool to share processing techniques some time.

[Stargrrl]

Welcome Sean and thank you for contributing. I looked through your album also, great images! Rebekah

[dodgeandburn]

Regarding sharing PixInsight techniques, I recently started keeping notes for each image. It can get rather complex. Maybe there could be Imager's Discussion forum to share this kind of stuff? Anyway, here are the steps I took for this image for those interested:

Start

1. The usual Bias/Darks/Flats calibration with BatchPrepocessing script.
2. CosmeticCorrection using Darks.
3. StarAlignment of all frames to the first L frame.
4. ImageIntegration of Lum, Red, Green & Blue frames separately.
5. ChannelCombination into RGB linear image.
6. DynamicCrop on all Lum & RGB to crop misaligned edges due to rotation from one night to the next.

LUM part

8. Create StarMask from Lum (mask created from an average of four masks, each having scaling set to 2, 4, 6 and . Applied star mask but disabled it.
9. DynamicBackgroundExtraction. Lots of experimentation and learning here trying to bring out the dustiness from the heavy light pollusion. Saved proccess icon for RGB.
10. HistogramTransformation - close in on final stretch, but not too far.
11. Enable mask to protect stars from blooming too much.
12. Final HistogramTransformation stretch.
13. Maybe a final curve to bring out a bit.. can't remember.

RGB part

14. Applied star mask and disabled it.
15. BackgroundNeutralization on RGB using preview box over good background sample.
16. DynamicBackgroundExtraction: Used saved process icon from Lum processing. Added a few more samples where it seemed to help.
17. HistogramTransformation - close in on final stretch, but not too far.
18. Enabled mask to protect stars from blooming too much.
19. Final HistogramTransformation stretch.


LUM + RGB part

21. Disabled all star masks (I don't know if these have any affects here...)
22. ChannelExtraction: L from RGB in CIE L*a*b colorspace.
23. LinearFit L to Lum.
24. ChannelCombination L back into RGB.
25. LRGBCombination Lum into RGB with Chrominance Noise Reduction and Saturation set for pleasing results.

Final part

27. HistogramTransformation and CurveTransformation to bring out the dust a bit more without blowing out the center.
28. Used a light touch of LocalHistogramEqualization to improve the contrast with the background a bit.
29. Gentle ColorSaturation boost.
30. Created a special mask in Photoshop to deal with annoying green/red color at the edges that DynamicBackgroundExtraction refused to deal with. Applied mask and desaturated with ColorSaturation.
31. A little bit of ACDNR with a light mask to reduce the perception of grit in the dim dusty areas.