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NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 76h!

Posted: Sat May 01, 2021 2:07 am
by ram
This 2021 reprocessed image of NGC7822 from 2019 data done using Topaz Studio (starting from the PixInsight SHO master light) was selected as the Stellar Shot of the Week for April 30, 2021. I was planning on redoing the image processing of this target with everything I now know but this was a pleasant surprise. I've not posted the reprocessed image here (just on my personal web and AstroBin pages) so here it is for the first time largely with the original writeup.

Nebula and open cluster B59/Ced214/LBN589/NGC7762/NGC7822/Sh2-171 (c-sho).
ngc7822_sho.v0.1-studio.resized5MB.jpg
Total integration: ~76 hours/4556 minutes = (153x7m + 52x6m for S2) + (155x7m + 72x6m for Ha) + (168x7m + 80x6m for O3)

Camera: QHY163M (16mp mono) CMOS cooled to -15 degrees C.
Telescope: Stellarvue SV70T triplet apochromat refractor @ f/4.8.
Reducer: SFFR70-APO
Mount: Paramount MyT.
Filters: Astrodon 5nm Ha, 3nm O3, 3nm S2.
Software: TheSkyXPro, Sharpcap, PixInsight, Topaz Studio.

Reduced quality/size image uploaded to forum. Full sized higher resolution image is here: http://ram.org/images/space/scope/1.4.4 ... 6m_76h.jpg and other older processing versions that I am not happy with can be accessed via my AstroBin page for this target: https://www.astrobin.com/0n8mh1/J/

NGC7822 is the designation given to young star forming complex (Berkeley 59) in the constellation Cepheus, whose surrounding environment has a distinctive skull-like appearance. The emission nebula (core region) is Sharpless 171 aka Cederalbad 214 and the wider field object with the loop/ear-like structure consists of both NGC7822 and the cluster of stars to the upper right that look like little white flecks of paint is NGC7762 (the ear within the ear). There is more to this nebula that goes down below and fleshes out the skeleton shape, but obviously doesn't fit within my FOV.

The emission nebula contains examples of objects known a "pillars of creation", active star forming regions that use the material in the nebula to shape the overall structures until there is no more raw material left creating a cavity in the middle (which is why some of these nebulae may start to look the same). The region is 3000 light years away, so it probably is still active. The field of view spans over 40 light years. The region also contains a supernova remnant somewhere (G118.3+0.48).

As of now, this is the target I've spent the most time on, taking 17 nights to do it all over a month (largely automated of course, but still) to end up with ~76 hours of useful data. It was a tough target for a variety of reasons but because the surrounding loop region is fainter than the central core, extra time was necessary to obtain some contrast and detail. Unlike with relatively brighter nebulae, where a few hours with each is enough and diminishing return sets in fast, I found that the longer the total exposure, the greater the contrast and detail I was able to obtain.

An additional frustrating thorn in my side was clouds. Multiple forecasts would state "clear", I would set up, go inside and then the clouds would come and go. There were few days of data collection where this issue didn't exist but fortunately PixInsight's image integration worked its magic and was able to register all but a few frames (though a few hours worth were weighted very low and this is after manually discarding over 50 frames that were completely cloudy). I did some integrations ignoring the worst frames but the difference was so tiny (and it was arguable as to which version was better) that I decided to use all the data I collected as long as the software didn't mind. Finally, another milestone with these images is that this is the first time I didn't rely on Photoshop to do the Hubble palette tweaking, relying only on PixInsight to do it.

My eventual goal is to do what I did with IC1396/Elephant's Trunk, which is to image in detail the Sh2-171 area in the middle to complement this widefield of the entire region. In that case, I did things the other way (core first, widefield later), but here I may be able to use this data to augment any detailed imaging of the core region.

As always, thanks for looking!

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sat May 01, 2021 11:37 am
by MariusD69
Wonderful! Great job, Ram!

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sat May 01, 2021 12:45 pm
by KathyNS
That's a spectacular image!

The NGC number was familiar, so I went back through my images and found my image of this target. Wow, it is a lot bigger than I thought! And I have acquired an Oiii filter since I took that one. So I can see myself re-visiting this target when it comes around again. Thanks for the inspiration!

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sat May 01, 2021 12:57 pm
by Larry 1969
SPECTACULAR!

Larry

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sat May 01, 2021 1:24 pm
by messier 111
wow , this image is magnificent , nice details and colors . thx

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sat May 01, 2021 5:16 pm
by Michael131313
Fantastic image Ram. Thanks for sharing.

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sat May 01, 2021 5:40 pm
by Gordon
Congratulations Ram on having your image selected as todays TSS APOD!

app.php/article/5-1-2021-tss-astrophoto ... of-the-day

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sat May 01, 2021 6:08 pm
by helicon
Congrats Ram! Superb image.

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sat May 01, 2021 7:24 pm
by Makuser
Hi Ram. This is a fantastic image of NGC7822. The sky looks like it's on fire, superb colors, and excellent details. Thanks for sharing your wonderful craft work on this capture Ram, and congratulations on winning the TSS APOD Award today.

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sat May 01, 2021 10:39 pm
by ram
Thank you everyone, and thank you Gordon for the POTD selection!

Kathy: I loved the nebula for its distinctive human skull shape and the teeth/mouth region is where most of it is taken but the full skull shape becomes distinctive only when you get the surrounding area. I am looking forward to seeing what you make of it!

--Ram

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sun May 02, 2021 1:41 am
by Gmetric
Absolutely amazing image, Ram. Congratulations on the APOD too.

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sun May 02, 2021 1:49 am
by starfield
Another spectacular image. Congrats on the APOD. Thanks for introducing me to this beautiful object.

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Sun May 02, 2021 4:28 pm
by Ruud
Wonderful detail in glorious colour.
Image
Awesome work. Congrats on the apod!

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Tue May 04, 2021 2:29 am
by XCalRocketMan
Incredible image and congrats on the well deserved TSS APOD. I know what you mean about the trials and tribulations of multi-night image capture. I was going to comment on the diminishing returns on really long integration time, but you explained why it was necessary in this case - and the results prove the point.

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Tue May 04, 2021 11:42 pm
by ram
XCalRocketMan wrote: Tue May 04, 2021 2:29 am Incredible image and congrats on the well deserved TSS APOD. I know what you mean about the trials and tribulations of multi-night image capture. I was going to comment on the diminishing returns on really long integration time, but you explained why it was necessary in this case - and the results prove the point.
Thanks! Exactly, there is no doubt the diminishing returns exist but I find it hard to gauge ahead of time and I also throw in ALL the data I collect (aside from ones that are clearly blank/cloudy - if I can make out the target with a stretch, I include it). PI is rarely unable to register something and if the math is right it should be properly weighted so I'd say it's most like a filter - you could take all my images and throw away half the (worst) frames and we'd end up with a similar image but I would have to spend the exact same amount of real time collecting the data. I have tried this experiment on a few images and visually couldn't tell the difference. I used the SNR criterion an PI and Juan told me that can't be used for this purpose. The way I think about it is there's a lot of high quality data if need be in the future I could reprocess. Also I look at what other people like Sara Wager have done for fainter targets like this and they also put in similar amounts of imaging time (and perhaps even higher quality).

(I'm still struggling with this the 131 hour wide field image of sh2-129 I've posted the narrowfield of - I am about 70% of the way done, nearly complete with the individual filter Master Lights. I once had a friend tell me there're no short cuts to good processing and I didn't believe him but I see now what he means. But I should be worth it. Also getting an QHY294M any day now so excited about starting this season with that!)

--Ram

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Fri May 07, 2021 1:05 pm
by OzEclipse
Beautiful image. Well deserved recipient of both accolades.
Joe

Re: NGC7822 nebula and open cluster in Cepheus reprocess selected as the Stellar Shot of the Week for April 30, 2021 - 7

Posted: Fri May 07, 2021 1:19 pm
by Ylem
Wow! That's awesome 👍