M13 - project

Non-astrophotographical description:
Globular star clusters orbit around the core of our galaxy like electrons around an atomic nucleus. This cluster is a quiet big one and it's very prominent and well known among astronomers. It contains several 100 000 old stars. Globular clusters typically consist of old stars but in M13 there is one single young star which propably came across and was captured by the gravity of the cluster. The cluster is 145 light years in diameter and it's located 25 100 light years away.
By the way, 1 light year is 9 460 000 000 000 km (if you don't know about metric units, learn about them! non metric units really suck because it's really uncomfortable to perform calculations with them...I have no idea, why they still exist in some countries ).

Astrophotographical description / project status:
I buried the old 8 bit .tif raw images and used 12 bit .nef files instead. I shot 41 of them (30 seconds at 6400 ASA, f/8) but many suffered from motion blur (the EQ-6 isn't such a hyper accurate mount) so I had to discard them. A considerable number of the remaining images refused to be registered in RegiStar...so at last I only got 15 images for stacking. Some of them still showed a bit motion blur or partially refused to be registered optimal.

Short description about the processing:
-converted all .nef files (Nikons raw format) to 16 bit .tif using the batch processing feature in Nikons software
-registered and combined the images in RegiStar using the median/mean combine
-set the levels in Photoshop (the image in the upper right corner shows the result up to now - it's the same scale as the big image)
-split the image into RBG channels unsing PixInsight
-deconvolved every of these channels separately in StellarMagic (gaussian Van Cittert algorithm)
-combined the results to an RGB image again in Photoshop
-sqeezed up saturation and applied an adaptive FFT noise filter
-set levels (again) and curves in PhotoShop
-applied a selective gauissian filter in Pixinsight - this filter really rocked on this M13 image (on other images I know, I hasn't done such a great job...)

Note: Problems occured while trying to register the images in RegiStar - some images are not well registered in the outer regions (but the cluster itself is registered accurately).

This image is no finished work, I'll add data until I'm pleased and then it'll be finished. So the appearance may change after each new update.

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Nikon D100
GSO 8 " f/4 Newtonian optics in selfmade truss tube
modified EQ-6 mount
Sigma APO 2x teleextender
coma corrector

Photoshop (curves, levels, cosmetics, colour)
Noiseware (adaptive FFT noisefilter with build in sharpenig function)
PixInsight (channel splitting, selective gaussian blur)
RegiStar(aligning, stacking)
StellarMagic (deconvolution)