a very quick M83

Benjamin (Ben) · #1 14-06-2018, 02:22 PM

36x10s subs in LRGB, so total of 24 minutes. Was really a session to work out focus offsets for filters but also an experiment in stacking very short exposures.Was happy with the experiment, although now I just need a thousand more of them! The image was very noisy given it was taken from my backyard through my 8" Newt - lots of vivd blue gradients to deal with.

RickS (Rick) · #2 14-06-2018, 02:46 PM

Noisy and colour is unusual but a good experimental result, Ben!

Benjamin (Ben) · #3 14-06-2018, 03:17 PM

Quote:

Originally Posted by RickS

Noisy and colour is unusual

Oh, why is that? I made a synthetic luminance (see below) and a RGB composite which I combined in StarTools.

Here are also more blurred versions. Better that way perhaps? Kind of like the view through the star destroyer window!!

RickS (Rick) · #4 14-06-2018, 03:52 PM

Quote:

Originally Posted by Benjamin

Oh, why is that?

Hi Ben,

There is quite a lot of variation in the colours that you see in images of M83 but it's usually blue and/or magenta rather than cyan/turquoise and purple. I understand it was just an experiment and you didn't get much data, of course...

Cheers,
Rick.

Benjamin (Ben) · #5 14-06-2018, 04:08 PM

Quote:

Originally Posted by RickS

Hi Ben,

There is quite a lot of variation in the colours that you see in images of M83 but it's usually blue and/or magenta rather than cyan/turquoise and purple. I understand it was just an experiment and you didn't get much data, of course...

Cheers,
Rick.

Ah, I see. I’ll see what I can tweak :-)

Benjamin (Ben) · #6 15-06-2018, 02:09 AM

Maybe one of these is better in regards to colour? The third one is kind of what StarTools gave me once the gradients had been removed. The fourth is the most recent (what I'm liking the most) and has some of the greenish hue removed from it and has some slightly softened edges (added mask fuzz) but nothing else. Realise its all very subjective but keen to get a basic grip on the more common approaches. Loved your image of course Rick.

kosborn (Kevin) · #7 15-06-2018, 05:43 PM

I vote number 4. Very nice!

Kevin

raymo · #8 15-06-2018, 05:48 PM

Ditto.
raymo

Atmos (Colin) · #9 15-06-2018, 06:35 PM

Getting correct colour with very limited data can be a real struggle but you’ve got there with your whole 24 minutes of data!

RickS (Rick) · #10 15-06-2018, 06:42 PM

Nice work on #4, Ben!

Lognic04 (Logan) · #11 15-06-2018, 06:44 PM

Nice! Your blacks are quite clipped however, meaning you are losing a lot of galaxy data.

Benjamin (Ben) · #12 15-06-2018, 08:43 PM

Very clipped blacks! Not sure I had the skills to do otherwise sadly. I assumed (perhaps mistakenly) there was little more I could get from the small amount of data given the noise already in the outer parts on M83. I also felt I had to isolate the galaxy as much as possible to get StarTools to deliver somewhere near the right colour balance (the last image, although still a touch green initially). The gradients were so full on (an over whelming blue then a residual green) that they seemed to skew any colour corrections in odd directions. Once the background was largely black the more familiar galaxy colours seemed to just pop out. The astrobin version is here if that helps - https://www.astrobin.com/351313/0/?nc=user
I’ll see if I can do a process that leaves a bit more grit in there :-)