M51 Whirlpool Galaxy (broad- and narrowband merge)

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Menno555
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M51 Whirlpool Galaxy (broad- and narrowband merge)

Post by Menno555 »

M51 the Whirlpool Galaxy

A merge of broadband and narrowband data (Ha + OIII), in total a bit more than 8 hours integration time.
Also first light for the Optolong L-eXtreme filter, a duo filter for 7nm Ha and OIII.
The color image is a blend of broad- and narrowband data. Also the capture of the only narrowband.

Bortle 7/8
Meade LX200 8" f/10 ACF OTA
Ioptron CEM25EC montering (no guiding)
Baader Neodymium Skyglow filter
Optolong L-Pro filter
Optolong L-eXtreme filter
Zwo ASI071MC Pro camera

Captured with SharpCap Pro @ -10 Celsius / White balance R50 B50
Baader Neodymium: 30 x 400 sec / Gain 0 / Offset 4
Optolong L-Pro: 11 x 600 sec / Gain 0 / Offset 4
Optolong L-eXtreme: 19 x 600 sec / Gain 100 / Offset 10

Stacked with DeepSkyStacker
Each set apart

Processed with Siril and Photoshop
Siril: Background Extraction and Histogram of each stack
Photoshop: layered the 3 stacks. Then Curves, Levels, Camera Raw Filter (blacks, color saturation, clarity, noise reduction)

M51 broad- and narrowband
M51 broad- and narrowband
M51_sm.jpg (492.91 KiB) Viewed 215 times
M51 narrowband
M51 narrowband
M51-H-sm.jpg (457.57 KiB) Viewed 215 times
timh
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Joined: Mon Aug 26, 2019 5:50 pm

Re: M51 Whirlpool Galaxy (broad- and narrowband merge)

Post by timh »

Very nice resolution and colour Menno. M51 is a great object that I always come back to. A picture to mark the end of 'galaxy season'? I also did a fair amount of galaxy 'work' - if you can call it that - 'play' more like - these past months and will also post up a couple of the best so far.

Incidentally - and you may never have tried it? I do find that when I image with no filter in place at all (except for IR/UV cut off) then the HA red regions just appear white - or maybe a faint pinkish white. Dop you see the same? All of the filters (even my UHC filter) make quite a difference in terms of enhancing the red - but your 'extreme' narrow band is certainly living up to its name.

Tim
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Menno555
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Re: M51 Whirlpool Galaxy (broad- and narrowband merge)

Post by Menno555 »

Thanks Tim.
And as coincidence will have it, I just ordered a 2" IR/UV cut filter with that in mind what you described :)
Till now I backed out of that cause of the Bortle 7/8 but I'm learning more and more with capturing but also with processing. Going to see if any light pollution haze can be "battled" :)

Menno
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Menno555
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Re: M51 Whirlpool Galaxy (broad- and narrowband merge)

Post by Menno555 »

Like usual i like to do some extra things with captures.
I had so much data of M51 that I decided to focus on the core.
Stacked everything again in DeepSkyStacker but now with 3x drizzle. In Photoshop I cropped the core area and reduced the highlights. This brought forward a lot more of detail. Of course noisy and not "sharp" but I am not disappointed with the end result :)
For comparison also a Hubble capture of the core which I made to the same scale.

M51 core Hubble
M51 core Hubble
kern_m51.jpg (228.18 KiB) Viewed 144 times
M51 core 3x drizzle
M51 core 3x drizzle
kern_m51_hubble.jpg (242.46 KiB) Viewed 144 times
timh
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Re: M51 Whirlpool Galaxy (broad- and narrowband merge)

Post by timh »

Very impressive Menno. You must have had sharp focus and and reasonable steady (even if bright at Bortle 7/8) skies because the detail at the core is really very good. I am surprised though that drizzle should have done much - and especially as high as 3X? I thought that it was mainly for use when undersampled and I would guess that you wouldn't be at F 10? Can't argue with the result though!

TimH
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Menno555
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Re: M51 Whirlpool Galaxy (broad- and narrowband merge)

Post by Menno555 »

Thanks Tim!
I use a Bahtinov mask together with the Bahtinov Grabber software and check focus every hour or so.
And this is what I did read on the drizzle too, so I never tried it. But I tried it now and somehow it worked. I did try also with no-drizzle stack but then when enlarging in Photoshop, to much got lost.
My PC had to work hard though: it produces a 2 Gb FITS file after much crunching and then in SiriL it's also not that fast anymore. But I have enough power in my PC and am not in a hurry :p

Menno
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