M42 Orion Nebula

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Startrek
Posts: 195
Joined: Mon Dec 30, 2019 3:49 am

M42 Orion Nebula

Post by Startrek »

It’s a bit early for M42 in the Southern Hemisphere as it doesn’t rise high enough until midnight ( more of a December to February target , our Summer ) However scored a clear stable night til morning so captured about 2.5 hours of good clean data with a descending 90% waxing moon.

Bortle 8 LP City / Suburban Skies
6” f6 GSO Newt
Skywatcher EQ6-R pro mount
ZWO2600MC cooled to -10C , Gain 100
TS Optics GPU coma corrector
Antlia ALPT 5nm OSC Dualband filter
55 x 3 min dithered guided subs
40 x Flats
60 x Bias
EQMOD, Stellarium, APT
Stacked in DSS
Processed in Startools V1.8 via Compose OSC Bi Color
Binned to only 71% to take advantage of SV Decon which worked beautifully on this target
No layering to expose the Trap ( didn’t capture any short subs ) just used HDR tame and Shrink to try to expose it
This is a works in process so hope to finish with 5 to 7 hours eventually over the coming months

SHO / HST version
SHO matrix 4th option
Synthetic Luminance version

Comments most welcome
Thanks
Martin
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admin
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Re: M42 Orion Nebula

Post by admin »

I don't know how, but you still managed to resolve the trapezium at 3 minutes exposures! :shock:
Looks like HDR is doing a great job and that you almost don't need shorter exposures to resolve the detail in the core!

Very nice.
Ivo Jager
StarTools creator and astronomy enthusiast
Startrek
Posts: 195
Joined: Mon Dec 30, 2019 3:49 am

Re: M42 Orion Nebula

Post by Startrek »

Hi Ivo,
Thanks for your nice comments
Whilst I’m finally getting my head around v1.8 and enjoying its new features, especially SV Decon , I still find that HDR reveal DSO core preset in v1.7 does a slightly better job on taming the core of M42 compared to HDR v1.8.
I have followed Guys user notes but HDR v1.8 tends to tame a wider region of the core and not concentrate on the smaller super bright area where the Trap exists

I’ve tried using the Reveal and Tame presets using brightness and shadow sliders but I find that v1.7 reveal DSO core arrows directly in on the Trap area and less in the outer areas of the core.
Only my observations
HDR v1.8 is incredibly powerful , in fact too powerful for my data sets so I only use it sparingly, otherwise my nebulosity regions tend to look like shattered safety glass

Yes I did end up getting good results in the core of this M43 image from HDR v1.8 exposing the Trap with some reasonable contrast

Most guys on our local forum use PI and PS and ask me how do I expose the core without Layering short subs, I tell them buy Startools and show you how to do it.

I keep pushing the Startools banner wherever I can

Thanks again

Looking forward to v1.9 hopefully early next year

Clear Skies
Martin
Mike in Rancho
Posts: 658
Joined: Sun Jun 20, 2021 10:05 pm
Location: Alta Loma, CA

Re: M42 Orion Nebula

Post by Mike in Rancho »

Nice job Martin. I suppose the 3m was plausible due to the use of that duo filter, which I think is pretty narrow? Good job on the HDR module, I can't see anything lacking here, and the transition into the (formerly) brighter areas where HDR is working is very smooth. Not noticeable really, which I guess is the point!

Unusual to see this in bicolor, but interesting.

Maybe my eyes are a little buggy, but it kind of seems like there might just be detection of the trap F star? :D I can't make out D though, but maybe that's too close in. :thumbsup:
Startrek
Posts: 195
Joined: Mon Dec 30, 2019 3:49 am

Re: M42 Orion Nebula

Post by Startrek »

Thanks Mike,
My Antlia ALPT OSC Duoband filter is 5nm Ha and 5nm Oiii
Although I’m getting good results with HDR 1.8 , I find it too powerful or aggressive using the default settings so Im always winding it back considerably.
Finally got my head around SV Decon in relation to Binning and Sampling. With good clean low noise data it’s fantastic at my image scales and focal lengths
If you can find trap Star D , then I’ve hit the jackpot , I can’t see it. I do wear glasses and have myopia, astigmatism, PVD and early signs of Glaucoma, so not the best eyes for visually spotting fine details

Clear Skies
Martin
Mike in Rancho
Posts: 658
Joined: Sun Jun 20, 2021 10:05 pm
Location: Alta Loma, CA

Re: M42 Orion Nebula

Post by Mike in Rancho »

It depends on the target and the data, but in a lot of cases I will change from 1.25 to 1.05, maybe 1.10, right at the outset. Kind of the "a little goes a long way" philosophy, or as you say avoiding shattered glass. I'll also often pull back on the brightness slider on the left. Dark enhance can sometimes go up though. :D

Increasing the smoothen can also help transitions, for something like the M31 core.

I think I botched my trap star identification. :oops: A, B, C, and D should all be pretty well visible even at 100% of the scale from your jpg. Uncertain if that was the bin size from ST or scaled down even more later? I thought I could see F, just off of the C star, just as a little pixel bump, but now I'm not so sure. And F was the one I meant wasn't visible to me.

Maybe the original tiff could pull it off, although it's getting pretty tight in there. Good chart here: https://skyandtelescope.org/observing/s ... trapezium/
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