M83 Southern Pinwheel Galaxy

[Startrek]

Captured M83 Southern Pinwheel Galaxy down under
Conditions were fairly good , low humidity and no moon around however only a 3 hour window before cloud arrived

NexDome Obs
Bortle 3/4
8” f5 GSO Newt
EQ6-R mount
ZWOASI2600MC Gain 0 cooled to -10C
Baader MPCC CC
ZWO EAF
29 x 4 min dithered guided subs
40 x Flats
50 x Bias
Goto and Nav EQMOD and Ascom Stellarium
Framed focused and captured in APT
PHD2 Multistar guiding ( 0.60 arc sec total rms )
Payload 14 kg
Stacked in DSS
Processed in Startools V1.7 OSC Linear data set

Original and Crop versions

Comments most welcome
Thanks

157576CC-90CB-4B72-BFBC-A55851929ECC.jpeg (696.79 KiB) Viewed 2807 times

[fmeireso]

Very nice! I like the blue tint. Great picture.

[Startrek]

Thanks for your nice comment
Clear Skies
Martin

[Mike in Rancho]

Wow Martin, you really have this down.

And in only two hours! I imagine the big scope and dark skies help, but still!

I can't get the MPCC to give me nice stars across the whole field. I'm also still fighting what I imagine is some kind of stray light bouncing around inside the Newt, though I can't tell if it's from the lights, the flats, or both due to a correction mismatch. It seems better than with the DSLR, but right now with only lum I can't be totally sure. Do you use anything to block accidental light pickup? I have the back end of the Newt covered, and also a neoprene sleeve around the focuser. And then my flats are in a dark room, with everything still covered, diffusion film, and pointing at a light panel a few feet away.

Only two nights of practice so far, but I've also been using gain 0, and then 30 darks, 30 flats, and 30 dark flats, all at 0C. I haven't tried to go colder yet.

Great that you've been getting good results out of DSS too, especially with its better speed for stacking. I've been getting much cleaner results out of ASTAP, as DSS seems to give me registration artifacts that seem like a grid across the entire image. Probably due to my wonky MPCC star shapes.

[Startrek]

Mike,
Thanks for your comments
An 8” f5 Newt isn’t really a big scope for Galaxy imaging. Most folk use 11 inch scopes or bigger with + 2000mm focal lengths
I call my scope an all rounder
I’m upgrading soon and have ordered a 10” f5 Carbon fibre Newt and EQ8-R pro mount to go in my Dome ( this is as big as I will ever go ) I will still use my 8” or certain nebula etc...
Took me a while ( trial and error ) to eliminate coma across the whole field with my 2600MC. Ended up being 57.5mm from Baader CC to sensor (definitely not 55mm )
I take my Flats after my lights using a white t shirt and Huion A3 led light dimmable panel which provides good control of illumination.I calibrate with Bias frames
Seems to work well. Again I experimented with Dark flats and Darks etc... these never worked
DSS does a great job stacking , never had a issue with DSS
Cooling the 2600MC to -10 C works well in both summer and winter , no need to go any cooler as dark current is super low on these cameras anyway and there is zero amp glow even after 5 min or longer subs

Clear Skies
Martin

[Mike in Rancho]

Thanks Martin,

Congrats on the new scope, looking forward to seeing what you do with it!

1000-1250mm is still pretty fair reach, even if there are EdgeHD11's out there. All a matter of just how small a galaxy is being hunted I suppose.

I'll try a little longer on my backspacing. I got to 57 on my Nikon and that was an improvement over the 55. The 2600 train should match the spacing, and the focal plane is in the same drawtube spot it seems. Of course the focus band is quite narrow.

Most of my reading though seems to indicate the MPCC is just hard and never quite right with f4. Crazy that there'd be such a difference between f4 and f5.

I'll start trying some lower cooling also. -10C should be within the capabilities of the cooler as long as it's below 80° out, which it almost always will be. I also need to try out the gain 100 option to see how much that shortens the well depth for my stars. The noise profile is quite a bit lower there. For sure I am likely to use that for narrowband filtered shooting.

Might try the bias-only too. All just feeling things out.

Thanks for the tips.

[Startrek]

Here’s a reprocess of M83 using Scientific aware in lieu of Artistic aware in the colour profile. Also tried the 50/50 Layering which gave the colour across the Galaxy a better balance
I think this version “pops out” a bit more in the core and the spirals compared to the original posted images

Comments most welcome

Clear Skies
Martin

[Stefan B]

Hi Martin,

I also liked the blue tinted version but I really love this more balanced rendition. Details are amazing in both, nothing changed in that regard. But in the new rendition one can also start to see the nebula regions which I always find fascinating...photographing regions of star birth in another galaxy...just awesome Especially when considering how extremely difficult it was to take pictures of the universe not too long ago (I just finished reading 'Starlight detectives" by Alan Hirshfeld on the matter - great read!).

Anyway, it's a shame that M 83 doesn't rise higher than 12° for me, but at least we have your images of these southern gems

Regards
Stefan

[Startrek]

Thanks Stefan