NGC7822 Emission Nebula in Cepheus (Alastairmk)

Celestial hemisphere: Northern · Constellation: Cepheus (Cep) · Contains: NGC 7822

NGC7822 Emission Nebula in Cepheus, Alastairmk

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NGC7822 Emission Nebula in Cepheus

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NGC7822 Emission Nebula in Cepheus

This emission nebula was imaged over 10 nights in September 2021, a time when there was high altitude smoke and cloud haze. The image contained some very bright stars amidst low signal SII and OII data that tended to create massive halos on top of faint nebular detail. Although I took 33 hours of narrowband data, only 27 hours survived my subframe selector criteria. I decided to eliminate all the narrowband stars using Starnet ++ in Pixinsight and substitute 5.3 hours of RGB 60 sec exposures processed to leave only the stars, that were added to the starless SHO image. Substantial halos remained even with 60 sec exposures but shorter exposures would have created problems with the faint stars. Even so, I could probably have done a better job at halo reduction. One lesson is to upgrade my basic ZWO filters and a new filter set is on the way for delivery early next year.

The image has a very strong Ha signal that tends to overwhelm much weaker but still significant SII and OIII which were apparent only after stacking the subs. I used a tone map processing technique that substantially boosted the SII and OII to give the sulphurous false colours of the image. I prefer them to the subtle greys of the unboosted image, but this may be a matter of taste (or lack of taste).

Image consists of:
Ha 102 x 600s
OIII 74 x 600s
SII 96 x 600s
R 84 x 60s
G 81 x 60s
B 74 x 60s
All at Gain 139, -15C for a total integration time of 31.2h

NOVAC

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The “AstroBin Image of the Day and Top Picks”, or IOTD/TP, is a long-running system to promote beautiful, interesting, peculiar, or otherwise amazing astrophotographs, with a focus on technical excellence. Learn more.

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Views by Submitters (available since September 19th, 2023) Every image is assigned to 50% of available Submitters. In the event that at least 80% of them don't view the image before its time in the IOTD/TP process expires, it's assigned to the other 50% of Submitters and the process begins anew.
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Status	Basic success
Started	...
Astrometry.net job	5046164
PixInsight job	n/a
PixInsight queue size	n/a
PixInsight stage	n/a

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NGC7822 Emission Nebula in Cepheus

NGC7822 Emission Nebula in Cepheus

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NGC7822 Emission Nebula in Cepheus

NGC7822 Emission Nebula in Cepheus

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