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Old 17-10-2023, 01:08 PM
Startrek (Martin)
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Join Date: Dec 2017
Location: Sydney and South Coast NSW
Posts: 6,676
NGC 253 Sculptor Galaxy 2nd Capture with 2600MM

There’s still quite a few galaxies positioned nicely in the east during the new moon so decided to experiment a bit more with broadband imaging under heavy light pollution using my 2600MM on NGC 253 Sculptor Galaxy.

Over a couple of nights captured 3 hours of Luminance and slightly more than hour each of Red , Green and Blue.

This time set the 2600MM to Gain 0 ( instead of Gain 100 )

Bortle 8 skies City Suburban
New Moon period
8” f5 Klaus Helmerich Carbon fibre Newt
Skywatcher EQ6-R pro mount
ZWO2600MM cooled to -10C , Gain 0
Antlia L RGB Pro series filters
ZWO 7x2” EFW
TS optics GPU coma corrector
Orion 60mm Guidescope with helical focuser
ZWO 120MM-S guide camera
190 x 60 sec Lum subs
75 x 60 sec Red subs
73 x 60 sec Green subs
75 x 60 sec Blue subs
Flats and Bias for all filters
EQMOD and Stellarium for Goto and tracking
APT capture software
PHD2 Multistar guiding ( 0.50 to 0.60 arc sec total rms )
Dithered every 2nd sub
Stacked using ASTAP
Processed in Startools V1.8 ( Data set loaded via Compose ) Luminance type L + Synthetic L , RGB , RGB

A couple of takeaways from this project -
The luminance data was way overexposed at 60 seconds under Bortle 8 skies. I tried processing with and without Luminance and found results were significantly better without it.
Moving forward , Luminance subs will have to be between 10sec and 30 sec maximum under these heavy light polluted skies. The 8” newt and the 2600MM with only a Lum filter just sucks in those photons and Skyglow ( not to mention neighbouring lights )
I processed just the R, G and B and Startools creates a Synthetic Luminance.
The image had less noise to deal with yet still had good detail.
Id wished I had 3 hours of additional RGB data rather than unusable Luminance data.
Switching from OSC to Mono is a big learning curve

Astrobin link below for full resolution…….

https://www.astrobin.com/izyu3e/

*** Also photo of initial auto stretch before gradient wipe , don’t you just love heavy light polluted skies !!

Comments welcome

Thanks for looking

Martin
Attached Thumbnails
Click for full-size image (NGC 253 Sculptor Galaxy Peak 60sec RGB only Gain 0 rev 2.jpg)
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Click for full-size image (IMG_4835.jpg)
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