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OR: 24/25 December



 
 
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Old November 24th 04, 06:20 PM
justbeats
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Default OR: 24/25 December

Relevant image at http://uploads.savefile.com/redir/31100.jpg
Technical details at the end.

------------------------------------------------------------
‘Twas the night before Christmas, when all through the house,
Not a creature was stirring, including my spouse.
As out in the yard, midnight seeing was good,
I snuck to my shed and I eased back the hood.

My shed's an observatory, (maybe you guessed),
Which needs mains electric to work at its best.
So I unplugged the tree lights and plugged in instead
A cable that led from the house to the shed.

Now dark-ready eyes are the best some will say,
Yet for me, CCD blows "eyes-only" away!
Thus with filter wheel on but no auto-guide set
I ventured to capture my best image yet.

But this is a challenge, you must understand
As my scope's a bit small and was bought 2nd hand.
I'm hankering after a h-u-g-e SCT,
But the gear I have now left me no money free.

Yet when GOTO had pointed to M42
Performance was almost too good to be true.
Trapezium wondrous; E, F and G clear.
R, G and B filters plus L would work here.

After some hours, all the light frames were caught.
It was time to take darks, lest my work be for nought.
Once that was done, and though dawns light was due,
I squeezed in a clutch of H-alpha frames too.

It was then that I fancied I heard a strange noise,
"Come Doner! Come Blitzen! Gee-up my fine boys."
See there, what's that red streak I can't keep my eye on?
It can't be! It is! Santa Clause in Orion!

Good fortune was with me, scope pointing just right,
And my CCD camera had captured his flight.
Although in the image he's small and he's blurred.
I'm sure it's Saint Nick that I saw and I heard.

Well I'd always thought Nick just a myth like the elves
And that folks begging gifts were deluding themselves.
But seeing him personally raised the great hope
That HE might provide me that much bigger scope!

No it wasn't the power from fairy lights drawn,
nor my poor tired eyes playing tricks before dawn.
I'd rather believe I saw something much better
‘cause next year I'm gonna send Santa a letter!

Just Beats
------------------------------------------------------------

Sorry for the Vogon poetry – came to me while I was capturing the
images. Given the impending season, I'm sure you'll all forgive me
wontcha! Incidentally, the image was taken Nov 12th, but "Twas the
night before November 13th" just didn't seem the right way to start
:-)

Technical details (for those who care). My goal was to make an image
that resolved the Trapezium and the fainter edges of the nebula
without resorting to PhotoShop tricks to blend together images with
different histogram stretches for the bright and faint bits.

I succeeded, but to be honest – it just didn't look right. The most
pleasing pictures had the central portion "burned out". So that's what
I posted.

It's an L(R+Ha)GB image taken with SXV-H9 on an Orion 80ED
piggy-backed on an LX200. All images unguided. I took 100 frames for
each filter with exposures ranging from 10 to 20 seconds. Total
exposure time (after winnowing some dodgy frames) is about 1 hour 40
minutes

All frames calibrated with master darks that I created a couple of
weeks before (100 stacked bias frames and 50 x 5mins dark frames),
then aligned and stacked in MaximDL/CCD. I used summing and worked
with the floating point versions until the last possible stage (noise
reduction). I found this did a better job of bringing out the faint
outer parts than averaging and working within 16 bit limits.

Processing was pretty minimal. Linear histogram stretch, mild adaptive
filter and unsharp masking then noise reduced in NeatImage (demo) to
smooth the faintest bits.

My first "serious" image. Shame the fat bloke got in the frame :-)

Cheers
justbeats
 




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