M17 Swan Nebula in LRGB with SHO data

[Startrek]

At my City suburban B7/8 location it’s near pointless to image emission nebula in LRGB broadband ( plus I don’t get enough clear nights ) so I worked out a way to use my narrowband acquired data set to produce a “simulated LRGB” image or close as possible to broadband visual spectrum.

I used my recently acquired M17 Swan Nebula SHO data.

Used the Compose module in Startools to map the SHO data set into an LRGB composite as follows -

Luminance Channel ( SHO )
Open Compose module
Load SHO data into RGB channel slots and set Luminance / Color to L+ Synthetic L from RGB, Mono
Save as TIFF
Close Compose module

Red Channel ( Sii + Ha )
Open Compose module
Load Sii data into R channel slot
Load Ha data into G channel shot
Set Luminance Color to L + Synthetic L from RGB , Mono
Save as TIFF
Close Compose module

Open Compose module
Set Luminance Color to L, RGB
Load previously saved Luminance ( SHO ) into Luminance channel slot
Load previously saved Red file ( Sii + Ha ) into Red channel slot
Load existing Oiii data into Green channel slot
Load existing Oiii data into Blue channel slot
Process and Keep

Once you hit the Color module select Color Style - RGB Ratio CIELab Luminance Retention and process accordingly.

The final result was pleasing , definitely not bonafide LRGB but close enough considering my heavy light polluted skies where narrowband is my only option when imaging emission type celestial objects.
It just provides another option and a bit more flexibility in my imaging and processing.

Attached simulated LRGB version in 200kb

Astrobin link below for full resolution……,

https://www.astrobin.com/uf78h5/


Thanks for looking
Comments welcome

Martin

[FrancoRodriguez]

beautiful shot mate, especially considering your light pollution

[Startrek]

Thanks Franco
Thanks for commenting
Yes Sydney’s ever increasing LP is a real problem but now I’ve found a nifty bit of processing to produce a Clayton’s LRGB or close anyway with Narrowband data.
Fortunately I have a NexDome Obs under Bortle 3 on the South Coast NSW , but getting away from Sydney down there is limited to odd weekends and school holidays throughout the year ( even though retired, minding a bunch of grandkids takes a fair chunk of our time, but wouldn’t swap it for the world )
Thanks again
Martin

[strongmanmike]

An interesting alternative approach Martone, looks good :thumbsup:

Aaah grand kids...I do hope I get some at some stage....I have so many grand stories to tell them about their Grandfather :P I'm sure they can't wait :lol:

Mike

[Startrek]

Thanks Mike,
I’m probably only a handful of imagers who use Startools to post process whereas the majority use Pi and PS etc…
Startools is extremely powerful and although only uses about 10 or 12 modules , most of them do a fantastic job. Folk who have experimented with it on trial versions have had trouble with its colour module , me I’ve had no real issues at all.
I found a link on the Startools forum ( 2021) about creating a “simulated LRGB image” from SHO data.
It worked quite well with a few tweaks.

Yes grandkids are a joy and hope you experience the same sooner than later , we have 6 of them , with probably more in the future as we have another son (37) and daughter ( 34 ) who look like getting married next year or the year after and both mentioned kids.
Gonna be busy into my late 60’s / early 70’s
By the way I’m “Pa the astronomer”
Cheers
Martone

[strongmanmike]

Yeah bit like me with Astroart (V2 through to V8), it's the only camera control, preprocessing and post processing specific software I have ever used, since 2003. I do use Photoshop too, CS3+ :)



I like that, I may use that too...if I ever get the privilege, strongman Pa wont make any sense by then :P :)

Mike

[Dave882]

Great result Martin and the colour is quite pleasing - some very nice detail through the body of the swan and you’ve done well to control dynamic range. I wouldn’t have guessed those combinations had you not gone into the detail! Astronomy from the city has a certain art to it for sure

[Leo.G]

That's a stunning image Martin!
I must get into shooting anything again (images), my mind is so scattered I can't think straight at the moment.
Grandchildren?
I can only hope but I fear it's never going to happen.

[Startrek]

Leo,
Thanks very much
Yes any type of Astro imaging does have therapeutic value no matter what the target or quality of the image. Good for the mind , body and soul
Cheers
Martín

[Startrek]

Thanks Dave
Much appreciated mate
It’s been a while hey ?
Yeh quite pleased about the “look a like broadband result” from narrowband data , I’ll be trying it out again on emission nebula.
Hope to see some of your images soon from that mammoth scope of yours as clear nights have been more consistent through July and start of August , about time.

Cheers
Martin