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Ceph and Cass

My go at M101


Shibby
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I'm not so sure about this one; My processing skills are failing me somewhat, but I also think longer exposures must be required to get the best from this galaxy, not that my sky will allow much longer! Some of the exposures were taken from Cornwall under dark skies, the rest at home - under orange skies :)

60x300s, ISO 800, 450d

150P-DS

Opinions and suggestions much appreciated!

gallery_5051_1080_978743.jpg

With a bit of context:

gallery_5051_1080_281496.jpg

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I think M101 is difficult to process Lewis and you have done a really good job. Noise is controlled really well for a DSLR. Some of the stars look a bit square, what causes that? processing on the star layer maybe?

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Thanks very much! :) I pushed quite hard to try and reveal the outer parts of the galaxy. It's controlling the stars that gives me the most hassle actually; I'm pretty sure that the corrector introduces aberrations on brighter stars, which is understandable as it's not low dispersion glass or anything.

If anyone fancies a go at processing the data themselves I could always share the stacked output? Just lemme know...

I think M101 is difficult to process Lewis and you have done a really good job. Noise is controlled really well for a DSLR. Some of the stars look a bit square, what causes that? processing on the star layer maybe?

The square-ish look is, I think, mainly due to the focuser tube taking a nibble out of the stars. Even though I have the DS version of the 150P, I still have to use nearly all the inward travel of the focuser, so the tube protrudes a long way into the OTA :-(

I also notice that the stars on the LHS are odd shapes - I checked the collimation but may have fallen victim to some mirror flop or something.

Hi lewis did you use darks ?

Nope, just flats. I find darks unnecessary once you have enough light subs; the dark signal stacks out with sigma rejection. I probably should consider using bias frames, though...

Edited by Shibby
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