Veil Nebula from 37 South: OSC CMOS #nofilter

[Phil Hart]

I'm joining the 'pandemic processing' crowd and finally looking at data from my dome captured scatter-gun style over the last two years or more, where neither time nor energy was focussed on finding and fixing issues. That may be a topic of a more reflective post some other time.

For now, here is 8 hours of the Veil Nebula, captured in July 2018 (how embarrasing is that?). Sometimes my images surprise me and this was one of those times. At 37 south, this doesn't get above 20 degrees so most of this data was captured around 15-20 elevation, with a bit of light dome from Maryborough (pop 10,000 25km away) to boot.


Takahashi FSQ (which I sold before processing this, oops :shrug:, also a long story)
QHY 367C OSC CMOS camera


Higher res: https://philhart.smugmug.com/DeepSkyAstrophotography/Nebula/i-b2GTF84

This is true one-shot colour RGB image - there is no narrowband data here which dominates most images of this object. After spending awhile on the background removal, the remaining background variation and colouration (e.g. yellow dusty areas to right of 52 Cygni) I believe are all fairly real. e.g. compare to this image: clarkvision.com/veil.nebula.200mm (https://clarkvision.com/galleries/gallery.all/web/veil.nebula.200mm.c07.25.2015.0J6A4 279-327.g-1400s.html). If you know of other deep RGB images of this I'd be interested in the link.

This image has also benefited from the time to download Rogelio's "Mastering PixInsight and the art of astroimage processing" eBook. A few tips from a master PI processor and the time and inspiration that goes with pandemic isolation meant I was able to try additional PixInsight workflow steps (pretty quickly and easily in the end). This image also benefits significantly from the StarNet++ module for PixInsight allowing stars to be reduced and nebula enhanced in separated image layers.

The workflow roughly:


Calibration, registration, integration with Weighted Batch Preprocessing
Dynamic Crop
Automatic Background Extraction (I found optimised ABE parameters more successful than DBE)
Background Neutralisation & Colour Calibration with default options
Histogram Transformation
StarNet module to create separate star mask and nebula images
Morphological Transformation to reduce star 'presence' (as Rogelio calls it). Some messing around with MT parameters required
Further Histogram Transformation for nebula layer
Colour Saturation for both
PixelMath to add two images back together
Final Lightroom tweaks for last bit of 'pop'

Second thumbnail attached shows raw image after integration only.

One of my favourite observing memories is hunting out the Veil Nebula in big binos from a dark site (with Aberdeen District Astronomical Society) when I lived in Scotland and I was somewhat addicted to imaging it as well. Never would have expected to do RGB image like this from here.

Phil

[gregbradley]

A fantastic image Phil. You processed it very well given the light pollution etc.

Greg.

[topheart]

Hi Phil,
This is an example of something positive coming out of the pandemic, for sure!

Thanks for the detailed discussion.

It has come out very well for an RGB image, very well indeed!
Cheers,
Tim

[Atmos]

Very nice Phil! I’ve got the ASI094 and I wouldn’t have expected the Ha and OIII emissions to have come up well without any filters!

[Peter Ward]

I knew we were in for a treat, but am astounded by the before and after difference. Quite remarkable. I think I would have gone, "nah, too hard" and moved on :)

Mastering pixinsight is an art in itself. You've done that and then some!

[FlashDrive]

Phil....that 1st photo is really nice.

[Andy01]

Nice work Phil :thumbsup: - good to see you catching up with these, looking forward to more! :D

[Retrograde]

Great work Phil.
I love seeing local renditions of these 'famous' northern objects.

[Placidus]

That's utterly exquisite Phil. The thing that really does it for me is the colour. I've seen many an image of the Veil where everything is cyan. Yours is lovely.

[multiweb]

Good one Phil. Lovely colors. :thumbsup:



I think you're right about the brown stuff on one side. I have a bit of it as well on a mosaic (http://www.astropic.net/astro/veil_FSQ_fff.jpg) I did in 2015 at astrofest with an old Q as well.

[Phil Hart]

Thanks Greg. A few experiments with background extraction but PixInsight deals with this surprisingly well.



Thanks Tim. Good to see you're productively imaging too - clearly I haven't been on IIS much for awhile either :-)



Yes I didn't expect it to be that clear and defined either. A great surprise for RGB imaging!



Thanks!



Thanks Andy. We're in the minority looking forward to isolation in a long dark winter (sort of)!



Thanks! I've tried to avoid chasing things so far north but now I'm going to have try more. M31 next??



Thanks. The IIS version is pretty extremely saturated but the colour holds up ok. It's a lovely target.

[Phil Hart]

Thanks Peter. I definitely said "nah, too hard".. for all of the last two years or so! Both with equipment and processing. So this is a very belated attempt to get deep sky imaging and processing back on track!

I've very slowly grown the PI skills. Confidence with a few extra of these workflow steps is going to help a lot.

[Phil Hart]

Thanks Marc - your mosaic is very helpful. A few of the subtle darker areas around the nebula patches are common to both images. I'll be having a closer look at that!

[Peter Ward]

Forgot to mention...while I have Keller's Inside Pixinsight...this one looks more comprehensive. Just bought a copy. Thanks for the heads-up. :thumbsup: