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Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 12:44 am
by Juno16
After many months of downtime due to poor skies (worst stretch that I can remember), I was able to get out and image 5 nights from 9/14-22 to 9/21/22. It was really, really nice to get back out and do some imaging. The last time that I got out was 5/28/22!

Even nicer to remember how it all works! Especially after many software upgrades!

I imaged 3 targets in the five nights. The Cave Nebula, NGC 7822, and The Iris Nebula.

The Cave Nebula was a very tough process for me. I had tried to image this target when I first bought the ASI533 MC-P camera and had little success for putting together an image that I liked, so I never finished the process.
This time, I still had lots of struggles. Not really happy with the image, but after several days, it is looking somewhat better to me. Still not happy with it and I probably won’t image it again.

What I am happiest about is the drizzled stars!

191 light frames. 180 seconds, gain 104 (about 9.5 hours)
Skywatcher HEQ5 PRO with Rowan Belt Mod
Sharpstar 61 EDPHII w/ 0.8 FR/FF (275mm)
ASI533 MC-PRO with Optolong L-eNhance filter
Captured with N.I.N.A., PHD2, and GreenSwampServer
Processed with Pixinsight (2x drizzle), and Adobe PSCC

Thanks for looking and comments and suggestions are very welcome!

Image

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 1:15 am
by Ylem
Very nice Jim!

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 3:52 am
by bobharmony
The full resolution version looks really nice, Jim. Glad to hear you finally had a run of good nights!

Bob

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 6:56 am
by BABOafrica
Hey, Jim. Nice to see an image from you after that long stretch of cloudy nights.

And you obviously did not forget anything or ever grow a little rusty.

Wonderful colors !!!

BABO

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 10:15 am
by Juno16
Ylem wrote: Fri Sep 23, 2022 1:15 amVery nice Jim!

Thanks a bunch Jeff!

bobharmony wrote: Fri Sep 23, 2022 3:52 am The full resolution version looks really nice, Jim. Glad to hear you finally had a run of good nights!

Bob

Thanks Bob. Not an easy process. Usually, I create several variations and peek at them for days until one of them finally “pop” for me, then I go that direction and finish the image. No “pop” on this one, but I finally settled on this version which has only minor coloration tweaks post stretch with moderate star reduction.

Thanks for your nice comments!

BABOafrica wrote: Fri Sep 23, 2022 6:56 am Hey, Jim. Nice to see an image from you after that long stretch of cloudy nights.

And you obviously did not forget anything or ever grow a little rusty.

Wonderful colors !!!

BABO

It was great to finally get back at it again!

Actually Babo, I was surprised myself that I had absolutely no issues with anything during the imaging process.
The only thing that I need to do is tweak the DEC worm since PHD2 guiding assistant reported some backlash. Even with that, PHD2 corrected for the backlash nicely. Guiding was in the 0.7 arcsec/px range and I had only 7 tossed light frames out of about 200 total.
I am glad that you like the color. It is very close to what came out of the camera with little tweaking.
My favorite part of the image is the stars!

Thank you sir!

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 12:59 pm
by Mac
Glad to hear you got out to image and that's a fine image you ended up with.

How do you drizzle stars?

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 2:09 pm
by Juno16
Thanks Steve.

Drizzle is offered in WBPP now under the Post Calibration tab.

Drizzle.JPG

It makes a huge difference in undersampled stars and helps improve image details. I think that there is a very small cost in dynamic range, but it is very small.
The Sharpstar 61 (like your Raptor) with my 533 has an image scale of 2.7 which is very undersampled and when the stars are zoomed in, they look blocky. Drizzling does an amazing job of smoothing the stars out and making them look smooth and round.

There is a price though. The process takes more time and disk space (images are much larger). To me, it is well worth it.

I like my results better by using WBPP to register the images, then I use the ImageIntegration and the DrizzleIntegration processes to manually integrate and drizzle. 2x has worked well for me.

I mentioned it to Steve @steve333 and he really liked the results too. See his posts: viewtopic.php?p=217448#p217448 viewtopic.php?p=217541#p217541.

David (Jockinireland) @Jockinireland has been using drizzle for awhile now.

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 2:48 pm
by MariusD69
Wonderful image! Great work, Jim!!

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 2:50 pm
by Mac
Juno16 wrote: Fri Sep 23, 2022 2:09 pm Thanks Steve.

Drizzle is offered in WBPP now under the Post Calibration tab.

I am familiar with drizzle. But you're doing this just on a star mask?

This is something I have yet to try. Thanks

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 3:03 pm
by Juno16
Mac wrote: Fri Sep 23, 2022 2:50 pm
Juno16 wrote: Fri Sep 23, 2022 2:09 pm Thanks Steve.

Drizzle is offered in WBPP now under the Post Calibration tab.

I am familiar with drizzle. But you're doing this just on a star mask?

This is something I have yet to try. Thanks

I probably didn’t explain well.

I drizzled the entire image. I think that drizzling does slightly improve details, but I drizzled the entire image for the improvement in the stars.
Could be an interesting experiment to try drizzling just the star mask.

And yes, I really enjoyed getting some nice skies sonthat I could get back to imaging!

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 3:46 pm
by STEVE333
The stars look beautiful Jim. Even when zoomed in they are all nice and round!
The Cave is a difficult target because there just aren't any details to bring out. Even in NB imaging it is a tough one. I think you did a nice job on it.

Steve

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 4:39 pm
by Jockinireland
Thats a really nice Cave Jim. I have tried it a couple of times and find it very hard to get anything decent on. I think @STEVE333 is right that there is not really detail to bring out. So I'd say youve done a great job on this.

Re: Finally Came Up For Air - Sh2-155 The Cave Nebula

Posted: Fri Sep 23, 2022 6:33 pm
by Juno16
MariusD69 wrote: Fri Sep 23, 2022 2:48 pm Wonderful image! Great work, Jim!!

Thank you Marius!

STEVE333 wrote: Fri Sep 23, 2022 3:46 pm The stars look beautiful Jim. Even when zoomed in they are all nice and round!
The Cave is a difficult target because there just aren't any details to bring out. Even in NB imaging it is a tough one. I think you did a nice job on it.

Steve

Thanks Steve!

I especially like your comment on the stars! I like them too!

I also really appreciate your information concerning imaging the Cave. I wasn't sure, but I had issues with it before and struggled this time. Good to know!

Jockinireland wrote: Fri Sep 23, 2022 4:39 pm Thats a really nice Cave Jim. I have tried it a couple of times and find it very hard to get anything decent on. I think @STEVE333 is right that there is not really detail to bring out. So I'd say youve done a great job on this.

Your comment is very much appreciated David! Very tough target for sure.

More importantly, I got a chance to get out and get some new data! I still have NGC 7822 and NGC 7023 to process. I have peeked at the Iris and like the results so far. It is really nice to have new data sets to work on.

Might even give M31 a go tonight. I imaged it last year with the Sharpstar when I had the bad objective. Time for another try!