NGC 5128 Centaurus A Galaxy from Obs

[Startrek]

First light capturing this galaxy from my dark site Obs with the 2600MM
Location: South Coast NSW Australia
New Moon
Conditions : average seeing
Captured over 2 nights ( first night had annoying local passing cloud which resulted in less imaging time window of opportunity)
NexDome Obs
10” f5 Klaus Helmerich carbon fibre Newt
Skywatcher EQ8-R Pro mount
2600MM Gain 0 , cooled to -10C
Antlia 2” Pro LRGB filters
TS Optics GPU coma corrector
ZWO 7 x 2” EFW
Orion 60mm guide scope with helical focuser
ZWO 290MM guide camera
Lum 60 x 120 sec subs
Red 32 x 120 sec subs
Green 32 x 120 sec subs
Blue 32 x 120 sec subs
Dithered each sub
Flats for LRGB filters
Bias frames from Library
Dark frames from Library
Total integration 5 hrs
Tracking and Goto EQMOD and Stellarium
Captured with APT
PHD2 Multistar Guiding ( 0.60 to 0.65 arc sec total )
Exposures evaluated in ASTAP
Analysed , Calibrated and Stacked with ASTAP
Post processed in Startools version 1.7 ( data set loaded via Compose , Luminance / Color set to L + Synthetic L from RGB, RGB

Fairly pleased with my first broadband LRGB galaxy image from the 2600MM at my dark site , certainly a big improvement from my 2600MC , with less noise and more fidelity and fine detail.

Link to Astrobin for full resolution……

https://www.astrobin.com/fclofu/

Comments welcome
Thanks for looking
Martin

[fmeireso]

Very beautiful image, imho. You dither after every sub..seems alot. Somebody told me 12 dithers should be enough to rule walking noise out. I start my sessions mostly with dithering after every sub but after 12 i change it too every 3 subs to save a little bit of time.

[Startrek]

Thanks
For only 5 hours of data I’m really happy with the result
The resultant noise after dithering, stacking , darks etc.., was almost negligible ( de noise only 2 pixels but I could have skipped it )
Now dithering , I’ve tested dithering over many years and found dithering every sub is definitely worth the additional time spent ( from 120 sec subs to 10 min subs )
For 60 sec subs I dither every second sub
There are so many variables with dithering like type of camera , mount performance , sky conditions, type of target , image scale and so on ….
The only way to confirm your dithering frequency is to experiment ( which I did do , hours and hours of testing on different targets years ago )
In my case both mounts at both sites recover from a dither within 12 to 15 sec so why takes chances with a imaging session of 3 to 6 hours , just dither every sub and you’ve done everything to minimise , fixed pattern noise , walking noise , hot and cold pixels , dark current noise etc…,
The only area where dithering becomes questionable IMO is with Lucky imaging ( 10 sec to 30 sec subs )

Clear Skies
Martin

[Mike in Rancho]

Nice capture, Martin! What a great target.

Sure looks like more than 5 hours, doesn't it?

[Startrek]

Thanks Mike,
Yes this Galaxy is definitely unique ( radio galaxy) and was discovered by the Scottish astronomer James Dunlop in 1826 from his crude timber observatory at Parramatta in Western Sydney , Australia ( prior to federation) My eldest son lived in Dunlop Street Parramatta a few years ago ( street named after the astronomer)
Whilst this Galaxy is a bit early to image ( didn’t reach 30 degrees Alt until 11pm ) it’s the first bright Galaxy to rise in our southern skies. April to June is the best time to image it

Whilst ST 1.7 is painfully slow I’m getting good results with all modules and this image is testament to that ( After using HDR and SV Decon in ST 1.8 for over a year now , it’s just not giving me satisfactory results )
I can conclude from this 2 night session that nothing beats Dark Skies when it comes to Broadband galaxy imaging.
The data was so clean and detailed for only 5 hours

Unfortunately I had to leave my dark site and return back to my main residence in Sydney for a family celebration, otherwise I would have captured another few hours of Luminance data and some Ha data for accent that evening as skies were excellent.

Clear skies
Martin