StarTools

It’s been nearly 2 months since I last imaged due to terrible rain , storms and floods which have lashed eastern Australia throughout February and March
Last night was clear at my dark site so took the opportunity to image the largest and brightest nebula under southern skies , NGC 3372 Carina Nebula
Full moon was up so the L Extreme filter came to the rescue
Seeing was quite good which reflected in tight guiding from the EQ6-R pro mount carrying nearly 15kg
NexDome Obs
8”f5 GSO Newt
ZWOASI2600MC set in Ascom Gain 0 and cooled to -10 C
Optolong L Extreme filter
EAF focuser
Goto and tracking EQMOD and Ascom Stellarium
Captured using APT
PHD2 Multistar guiding ( 0.43 to 0.48 arc sec error total )
42 x 3 minute dithered guided subs
40 x Flats
50 x Bias
Stacked in DSS
Processed in Startools V1.7 Compose OSC Bi Color
SHO versions

Comments welcome
Thanks

Decided to reprocess this image with a more conservative approach
No HDR
Less sharpening
Less Decon
Used the interpolate colour Matrix

Added a few crops to show fine detailed amongst clouds of dust and gas

Comments welcome

Thanks

Very nice target, and neat-looking stuff.

If only I could get my diffraction spikes to be that sharp.

Thanks Mike,
NGC 3372 is one of the Southern Hemispheres biggest and brightest Nebula 120 x 120 arc mins , so many areas to explore and image
You want sharp diffraction spikes !
Recipe ...,
Good to very good seeing
Precise Collimation
Clean optics ( mirrors )
F5 to f6 focal ratios ( f4 diffraction spikes tend to be shorter )
3 to 5 min subs on a higher dynamic range
Star mask leaving just your spikes sampled and set Decon to 1.8 to 2.2 pixels

Clear Skies
Martin

Startrek wrote: ↑Fri Apr 22, 2022 11:03 am Thanks Mike,
NGC 3372 is one of the Southern Hemispheres biggest and brightest Nebula 120 x 120 arc mins , so many areas to explore and image
You want sharp diffraction spikes !
Recipe ...,
Good to very good seeing
Precise Collimation
Clean optics ( mirrors )
F5 to f6 focal ratios ( f4 diffraction spikes tend to be shorter )
3 to 5 min subs on a higher dynamic range
Star mask leaving just your spikes sampled and set Decon to 1.8 to 2.2 pixels

Clear Skies
Martin

Thank you for the recipe, Martin.

I did just clean my mirror a few days ago, followed by a fresh collimation, and I think both helped. Didn't realize the f/ratio was involved, but I am kind of stuck with what I got there...same with seeing.

The deconv technique seems just a wee bit manipulative , but also a throwback to 1.7?

Mike,
I missed 2 more important ingredients

Tight focus
Tight guiding , but I suppose that comes with good to excellent seeing conditions anyway

As far as Decon goes with setting a custom mask ,IMO I don’t believe it’s manipulative otherwise “all image processing” especially sharpening and noise reduction be it mathematically applied correctly is manipulative, due to all of us imaging through 60 miles of atmosphere causing all sorts of optical issues with our data

Clear Skies
Martin

Hmm I'm not so sure, Martin. But the focus and good guiding make sense also. I think I really need to get myself some good, 2", collimation tools.

I may very well be misunderstanding your use of deconv too. In 1.7 the mask is to block out singularities and very bright white areas like larger stars, due to the tendency to artifact, correct? So if the spikes are just set to be deconvolved along with everything else, rather than marked as a singularity, that indeed seems proper. If instead it is only the spikes, I would be a little more hesitant, but I guess it would still be based on the image PSF, right?

Likely moot in my case anyway as I really like 1.8 and have not gone back in a long time now.