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PostPosted: Mon May 14, 2012 4:14 pm 
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Hi folks,

I've been grabbing subs of the Pinwheel Galaxy (aka M101) over the last month or so as the opportunity arose. Despite some tracking problems I'm happy enough with the result to share:

    Image

    7 x 1,000 seconds Red, 9 x 1,000 seconds Green, 5 x 1,000 seconds Blue and 1 x 200 seconds Blue
    TEC 140 'scope (980mm focal length, f/7) plus ML16803 camera

By the way, that 200 second Blue sub crept in by mistake but it doesn't seem to have hurt things!

Processing: a brief summary. Usual processing in PixInsight summed all the subs to produce a luminance image which was star masked and HDRMultiscaleTransform-ed to bring out a little more structure in the galaxy. The RGB subs were stacked separately and then combined with the luminance image to produce a colour image - maybe I overdid the colour boost but I wanted to emphasise colour variation in the Pinwheel Galaxy itself. Both were fed into Photoshop. The luminance was spilt into "Just Stars" and "No Stars" versions and the "Just Stars" version was fed back through PixInsight for a spot of deconvolution before appearing once again in PhotoShop. The "No Stars" version was cleaned up and for the first time I used the Topaz Labs "InFocus" Photoshop add-on which produced some worthwhile improvements. The processed "No Stars" and "Just Stars" images were combined (Layers, Screen mode) and then the colour image, after a little tweaking, was used to add colour (Layers, Colour mode).

Here's a slightly closer view (roughly a 50% crop factor) of the Pinwheel Galaxy framed to include a couple of other more distant galaxies:

    Image

By the way, there's a bright blue star in M101. The colour may be due to the length of time (nearly a month) between the Blue subs and the rest of the exposures but the object itself is SN 2011fe. You can read about it here at Wikipedia. I've highlighted it in the following image:

    Image

From the Wiki article: "The star, formerly a white dwarf, is located in Messier 101, the Pinwheel Galaxy, 21 million light years from Earth." My first supernova and the capture wasn't even planned. :oops:

Bob.

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OM-D E-M1 + ED 12-40mm f/2.8, H-F007014E, M.ZUIKO DIGITAL 45mm 1:1.8, M.ZUIKO DIGITAL ED 75mm 1:1.8, L-RS014150E.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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PostPosted: Mon May 14, 2012 7:50 pm 
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Nice!

Now, why doesn't mine look like that? Don't answer that by the way, I already know...

With a small pixel peeping hat on, the crop looks rather speckly, is that colour noise or is it supposed to be like that as memory suggests this particular galaxy is rich in H-alpha?

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Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


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PostPosted: Mon May 14, 2012 9:30 pm 
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Hi popo,

I may return to the Pinwheel Galaxy at some point with the H-alpha filter but it's getting too close to the meridian right now and once it's clear on the west I can already see the North America nebula and that is my priority target for the summer. Showers are forecast tonight so I won't risk it with a mains powered computer and 12V power supply open to the elements next to the 'scope but hopefully Tuesday night will be clear although I won't be able to get started until after midnight. Sometimes having a social life just has to take priority! :)

Bob.

_________________
OM-D E-M1 + ED 12-40mm f/2.8, H-F007014E, M.ZUIKO DIGITAL 45mm 1:1.8, M.ZUIKO DIGITAL ED 75mm 1:1.8, L-RS014150E.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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