A belated Orion's Belt

[Fegato]

Captured this data in January, as I thought it would be a fun challenge to try and put together a wide field covering the whole Orion's Belt area. It's a 4 panel mosaic. However, my first attempts at processing this were not successful - issues with gradients across the different panels (caused by the vignetting I suffer from rather than LP), exacerbated by my desire to stretch this quite hard to pull out the dusty details all over the frame, made the end result a bit of a mess. Since then I've learned a bit more about the options in PI's PhotometricMosaic script, as well as discovering a starless technique with DBE which I now use all the time - so I've had a go at re-processing, which has been more successful. The other main challenges were (a) using masks in some of the stretches to keep the brighter areas under control and (b) getting the bright belt stars to fit back in reasonably naturally after starless processing of the rest.

I've also attached a crop showing just the more often imaged Horsehead / Flame nebulae area.

RASA 11 v2 on CEM120, ASI2400MC Pro (no filters), total 3h 27m across the four panels, captured on 23rd and 25th January.

[Mr Spock]

Well worth the wait. It looks absolutely incredible - as good as it gets 👍

[Roy Foreman]

Very nice. Love all the dust. Well worth all the processing hassle. I never seem to get mosaics to fit seamlessly, which makes you image all the more impressive.

[Fegato]

11 minutes ago, Roy Foreman said:

Very nice. Love all the dust. Well worth all the processing hassle. I never seem to get mosaics to fit seamlessly, which makes you image all the more impressive.

Thanks Roy! I had mixed results with mosaics until I started using the PI Mosaic scripts - I've found these to work really well, and as mentioned above, I've learnt a bit more about some of the options available which has helped too. This has all been necessary learning, as I use mosaics a lot - mostly because I don't rotate my camera at all, so often need them in order to get a subject framed properly (downside of RASA - camera rotation is prevented by need to manage tilt, upside of RASA - 2 frame mosaic doesn't take too much time!).

[simmo39]

Stunning! So much to see.

[ONIKKINEN]

Wow! That's a lot of dust. Top shelf processing too, really a winner image right here.

[AMcD]

Just stunning.  A triumph 👏

[Bargy]

Absolutely awesome mate. I just started this year and am learning Pixinsight from scratch - I learn the starless DBE from Adam Blocks website and it’s so much easier that doing DBE with stars 

[Fegato]

10 hours ago, Bargy said:

Absolutely awesome mate. I just started this year and am learning Pixinsight from scratch - I learn the starless DBE from Adam Blocks website and it’s so much easier that doing DBE with stars 

Thanks Bargy!  Yes, I got the method from an Adam Block youtube post, and it's really helped a lot. I'm normally trying to pull out dusty detail, and it's so hard to know what you're looking at with all those stars. I'd got to the point that I just gave up and used ABE on some images, which never worked that well.

[symmetal]

Lovely image. 🤗 The surrounding dust almost 'outshines' the usual Horsehead area in the full mosaic. Yes, PhotoMetricMosaic does seem to perform very well in blending the panels without having to do a lot of preparation beforehand.

I notice that there's little colour in the stars. I use PI GeneralizedHyperbolicStretch for most stretching operations now, and for the first iteration of around a half strength stretch, I select the Colour Mode in 'Colour Options' rather than the default RGB mode, as that preserves the colour during the stretch, similar to using an Arcsinh stretch, and then use RGB mode after for further streches. 

Alan

[Fegato]

Thanks Alan.  Yes, it's quite hard to get the stars colourful with the RASA and a "long" 30 second broadband exposure! I just tend to push the saturation a little bit after separating the stars from the image. I know many use MaskedStretch or arcsinh, but I find these give me star profiles that I don't like - and I'd rather have a nice star profile and less colour tbh. I have tried GHS a bit, but not much - I'll give it a go in the way you describe and see how that goes.

[symmetal]

Yes, I've tried using the Arcsinh stretch itself but found it gave saturated or near saturated stars random pixels of 1 colour so gave up using it. Converting to HSV and using the 'Repaired HSV Separation' script beforehand is meant to fix this, but I never found it changed very much. GHS doesn't seem to produce this effect so see if you like its results. There are some good Youtube tutorials on using GHS, and one of them suggested using this 'Colour mode' initially to maintain star colour.

Alan