M17 Swan Nebula in SHO and Synthetic LRGB from SHO data

[Startrek (Martin)]

July has been an excellent month for astrophotography with plenty of clear and relatively stable nights. Decided to image M17 again as it was placed nicely to image over the whole month with not too many obstructions in my FOV.
Captured a decent amount of data this time over 7 nights with conditions quite good , no moon , no dew and stable skies.

Even with 20 hours of data from those 3nm filters and no moon around, the image still had a decent level of fine noise grain which was easy to mitigate.

Pretty happy with the final results.

Bortle 8 City Suburban location
New Moon period
Seeing conditions average to good

Telescope 8” f5 Klaus Helmerich Carbon Fibre Newtonian ( Self Built ) focal length 1050mm
Mount Skywatcher EQ6-R Pro
Imaging camera ZWO2600MM cooled to -10C , Gain 100 HCG
TS Optics GPU coma corrector with Beamtech 15mm spacing ring
Antlia 3nm filters
PHD2 Multistar guiding ( 0.45 to 0.60 arc sec total )
Orion 60mm guide scope with helical focuser
ZWO EFW 7 x 2”
ZWO EAF focuser
Tracking and Goto EQMOD and Stellarium
Aquisition and Capture , APT

Ha 212 x 2 min dithered subs
Oiii 195 x 2 min dithered subs
Sii 195 x 2 min dithered subs

Full Calibration Suite
Darks from Library
Flats for Ha , Oiii and Sii
Flat Darks for Ha , Oiii and Sii

Total integration 20 hours

Subs reviewed in ASTAP
Subs analysed, calibrated , stacked and aligned in ASTAP

SHO version post processed in Startools version 1.8 via Compose module using Luminance / Color : L + Synthetic L from RGB , RGB.

Synthetic LRGB post processed in Startools version 1.8 via Compose module ( created Luminance channel from SHO mono , created Red channel from Sii + Ha and used Oiii for Green channel and Oiii for Blue channel) Luminance / Color L , RGB.

Synthetic LRGB is a fun option to have particularly when you image under B8 heavy light polluted skies and only have limited opportunities ( Weather and Moon ) to image Broadband. It isn’t easy having to capture 1000’s of 30 sec subs , very laborious in review , stacking and post processing.

Attached 200kB versions Native size , Crop and Super Crop for a closer view

Astrobin links for full resolution……..,

https://www.astrobin.com/9pjv0l/

https://www.astrobin.com/7daf3m/

https://www.astrobin.com/b20d3u/

https://www.astrobin.com/i7hhvk/

https://www.astrobin.com/bvazr3/

https://www.astrobin.com/50r6ye/


NB: This image is presented as documentary astrophotography and has not use any AI enhanced or AI assisted technology during post processing.

Thanks for Looking

Comments most welcome

Martin

[TrevorW]

Nicely done Martin

[Startrek (Martin)]

Originally Posted by TrevorW

Nicely done Martin

Thanks Trevor,
I might do a repro and look at more contrast , a bit more of a stretch and peg back the Starfield a tad. One tends to go over their images at least once or twice to look for improvement.

My son and his fiancé live at Yallingup and work in the wine industry, it’s been raining and windy for weeks. I’m assuming Perth has had similar weather conditions ?

Thanks again
Martin

[TrevorW]

Yes cold and very wet, couple of clear nights recently but too cold for me to bother, I just changed my setup back to the big scope, galaxy season

[strongmanmike (Michael)]

Lot's of lacey detail in there Martone, cool

Mike

[Startrek (Martin)]

Originally Posted by strongmanmike

Lot's of lacey detail in there Martone, cool

Mike

Thanks Mike,

July was a ripper month for Astro , conditions varied but at least I got down south to the Dome for a couple of weeks plus on return to the big smoke a week of clear nights under B8 …. yuk
I did a repro and added some more detail to the Swan with a Ha accent layer in Balmer series , come out ok , I might post it ?

Martone

[Nikolas (Nik)]

Very nice Martin lot's of detail especially in SHO

[Startrek (Martin)]

Thanks Nik,
Much appreciated
I’m working on a repro using the NB Accent module in Startools to pull out more faint detail ( dust , gas and nebulosity) in the outer regions without sacrificing too much in the core region and at the same time keeping the noise floor under control.
The NB Accent module is primarily used for LRGBHa renditions ( Galaxies and other Broadband nebula etc… ) but I’m going outside the square to create 2 more versions of the existing…..,
SHO with Ha Accent
Synthetic LRGB Ha
I’ll post tomorrow

Cheers
Martin

[Startrek (Martin)]

I decided to reprocess my recent M17 to see if I could expose a bit more detail , so tried the NB Accent module in Startools. Although this module was originally designed to highlight visual spectrum data with Narrowband accents ( Galaxies and Broadband reflection nebula etc…. LRGBHa ) I thought why not give it a try on Narrowband data.
To my surprise the results were really encouraging for such an unorthodox use of this tool.

SHO with Ha accent Balmer series
Synthetic LRGB from SHO data with Ha accent Balmer series

I had to adjust Color Modify in the NB Accent module back to 40% to ensure the original SHO and LRGB color palettes were not severely compromised.

Quite pleased with the final results

Astrobin links for full resolution below …..,

https://www.astrobin.com/m0tb33/
https://www.astrobin.com/al1ojp/
https://www.astrobin.com/ai03bo/
https://www.astrobin.com/d15ra4/


Thanks for looking

Comments welcome

Martin

[Nikolas (Nik)]

Great job the final results are so detailed

[Startrek (Martin)]

Originally Posted by Nikolas

Great job the final results are so detailed

Thanks Nik,
I’ve used the Startools NB Accent module before with great results on broadband targets like M83 and M20 with a LRGBHa composition.
It was just an afterthought to try it on Narrowband as it was never designed for Narrowband but hey it worked out ok.
It’s such an easy process and all the work is done behind the scenes like everything in Startools. In the Compose module just load your Sii data into R , Ha data into G ,Oiii data into B then load your Ha again into the NB accent channel. Process as normal and when you hit the NB Accent module it presents a AutoDev stretch view of the Ha luminance data which you can adjust to taste , hit next and bingo it’s all done. You can then adjust colour and brightness ( gamma ) and other parameters to taste.
I’ll be trying it again on the next narrowband target.

Cheers
Martin

[Ryderscope (Rodney)]

A great project Martin and a good way to explore different colour pallets and processing techniques.