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PostPosted: Fri Apr 05, 2013 1:50 pm 
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Hi folks,

I've been reworking some old data of the Soul Nebula and got a bit of a shock: so many colours in the stars! The processing is detailed in this thread over at the PI forum for those who wish to find out more. Here is a 100% crop from near the top left of my 4096x4096 pixel image:

    Image

Just an otherwise nondescript patch of sky but so beautiful when the star colour is retained.

And then there's this:

    Image

For orientation north is up and you can just see IC 1871 making an appearance in the top right of the frame. Pretty enough but there's something star-like, faint and very blue about one third of the way down and three quarters of the way across from the left. As near as I can judge it is at 02h 58m 50s, +60° 37' 22" but that was working from TheSkyX and purely by eye so the position probably isn't that precise. It doesn't appear to be noise but I can't identify it. The RGB subs were all captured on the evening of September 18th last year so whatever it is or was is now old news but I never spotted it when I originally processed the data because at that time I still hadn't discovered how to retain the star colours during a stretch.

For reference here's the whole frame reduced in size by a factor of four:

    Image

This has some decidedly experimental processing of the Ha data (8 x 1500 seconds) as I was trying to enhance the fine detail while still controlling the Ha intensity so as to allow those star colours to shine through.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
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PostPosted: Fri Apr 05, 2013 3:21 pm 
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Wonderful images Bob. I won't pretend to know what you're talking about but I've never seen pics like these, with the colours retained. Truly deserving of the description "awesome."


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PostPosted: Sat Apr 06, 2013 1:01 pm 
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Glad you like it. 8)

I've now released a 2048x2048 pixel version of the above image here. I've also released a version without the bulk of the Hydrogen alpha emission:

    Image

It works much better if you can view it against a dark background rather than the forum's bright colour scheme. The 2048x2048 pixel version is available here.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
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: Sat Apr 06, 2013 3:46 pm 
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Bob, where is the position of your blue star in the soul image? I'm really not set up for coordinates and work best if you more or less point at it! Or reference it relative to something else unmissable. I can have a look at my old data and see if I can find it too...

Edit: never mind, I found it now! You confuzzled me with the Ha inclusive version, and it was only clear once I saw the version without. Now to find my old data...

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PostPosted: Sat Apr 06, 2013 4:22 pm 
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Managed to find my last attempt at this. I managed to find the same bit of sky, scale and rotate it to match Bob's and will present it below.

Image
First here's Bob's version again, hope it's ok to link it to give easier reference below.

Image
This is my version with minimal processing to levels. I had to upscale quite a lot since I was going for both of heart and soul in one image (see below). There may be something there where the blue star is?

Image
And this is the above but made a LOT brighter, never mind quality. Definitely something in the same position, but my quality is just not there!

Image
This is what I had to crop from... scaled down lots.

Anyway, whatever it is, it is still there when I took those shots on 5th Dec. 2012.

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PostPosted: Sat Apr 06, 2013 4:56 pm 
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Hi popo,

Well found!!!

The 8 bit RGB values, as derived from my 16 bit Photoshop PSD file are 25, 92 and 129 respectively at the core and the entire object spans a 3x3 pixel matrix. Those RGB values are obviously affected by things like white balancing but the blue/green excess is pretty remarkable as the other blue stars in the frame typically have red and green much more equal and, obviously, a blue value higher than the red/green.

At the risk of speculating about things that lie above my pay grade I'm guessing that we can rule out a supernova given the length of time between our respective captures. Might it be a jet facing us from an active galaxy nucleus? Whatever it is it has highlighted my lack of resources in trying to track it down. Google is pretty good for a lot of stuff but it doesn't seem to understand right ascension and declination! :lol:

Many thanks for your input. I love a mystery and this is a good 'un. 8)

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
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 Apr 08, 2013 9:32 am 
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Hi popo,

That blue "star" can also be see here on the Aladin previewer. Star colours aren't so strong and there's no separate green channel. The J2000 coordinates of the image are RA: 02 57 45.0, Dec: +60 34 18. If those coordinates are for the image centre then my previous estimate of the position wasn't too good. I'm still trying to track down what exactly that object is.

Update: Got it! It is star "2MASS J02574541+6034251". The Simbad page includes a link on the spectral type line which points towards an article (PDF link) which offers a more human friendly name of Lan 272, the Lan being short for Lanning. Lan 272 is one of "Lanning's Stars" and is a "UV bright" white dwarf and the article also goes on to show a spectrum of Lan 272 which shows why the star appears so blue in my image. And if I'm reading Table 2 of that article correctly Lan 272 has an effective surface temperature of 90,410° K. :shock:

    Image

      Lan 272- effective temperature 90,410° K. :shock:

So I think I can claim a win for my new processing workflow. It allowed me to find something totally new to me, although already well documented in the literature! :)

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
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 Apr 08, 2013 11:58 am 
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Good hunting skills there! Next step: how's your sensor response to UV light?... :D

I know with conventional sensors there isn't that much leeway outside the visible spectrum, but it is on my have a go list to try imaging in those areas too. Actually, never mind that, I just remembered most optical glass isn't great with UV anyway.

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Lenses: EF 35/2, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 10-18, 15-85
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 50/1.4A, 150 macro, 120-300 f/2.8 OS
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PostPosted: Mon Apr 08, 2013 12:11 pm 
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Hi popo,

The short answer is "I don't know!" The image above was taken using my Astrodon filters.

But hey, we are now members of the 90,000 club, having both captured photons from a star with an effective surface temperature hotter than 90,000° K. 8)

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
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: Tue Apr 09, 2013 6:05 pm 
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Hi folks,

It is pretty technical but for those with time on their hands but who aren't convinced that the stars should be so highly coloured I've posted an analysis here at the PixInsight forum.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
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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