NGC7293 Helix Nebula under City Suburban Skies

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Startrek
Posts: 401
Joined: Mon Dec 30, 2019 3:49 am

NGC7293 Helix Nebula under City Suburban Skies

Post by Startrek »

Captured the Helix planetary nebula during a rare run of clear nights under my City suburban B8 Skies during the New Moon period with mixed results.
Acquired the following data over 5 nights -
160 x Ha 3 min dithered subs
152 x Oiii 3 min dithered subs
106 x Sii 3 min dithered subs
Total integration approx 21 hours
Full calibration suit -
Darks
Flats
Flat Darks
8” f5 Klaus Helmerich Carbon Newt
Skywatcher EQ6-R pro mount
Imaging camera ZWO2600MM , cooled to -10C , Gain 100
Antlia 3nm filters Ha , Oiii , Sii
PHD2 Multistar guiding ( 0.45 to 0.60 arc sec )
Tracking and Goto EQMOD and Ascom Stellarium
Captured with APT
Analysed , calibrated , aligned and stacked in ASTAP
Post processed in Startools V1.8
Used the SHO data set to create a Synthetic LRGB spectrum image via Compose.

The end result was a bit disappointing considering the amount of data acquired as I expected to expose more outer detail which ended up being just noise.

Faint objects like the Helix definitely require substantially more data to resolve fine detail under heavy light polluted B8 skies. However in saying that there is a point of diminishing returns when imaging under severe LP. In addition, if the moon was up I would never have attempted to image this object.

I decided to capture Sii data which is extremely faint but ended up just stacking noise which didn’t help.

In hindsight I should have captured significantly more Oiii data as this filters signal is severely compromised with noise under B8 , 10 times worse if the Moon is up.

Also conditions were average with poor seeing from 8pm to 10pm on each night.

Anyway processing was very conservative as I didn’t want to expose the background noise , gradients and undulations etc.. so background does appear clipped but it’s not as Startools won’t allow the blackpoint to be 0.

Astrobin link below for full resolution………,

https://www.astrobin.com/su9nt3/

Thanks for looking

Comments welcome

Martin
Attachments
NGC 7293 Helix Nebula Synthetic LRGB crop rev 1.jpeg
NGC 7293 Helix Nebula Synthetic LRGB crop rev 1.jpeg (718.33 KiB) Viewed 1915 times
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