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M101, finally...


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9x 3 min exposures, ISO 640, darks and bias, forgot to do flats (doh), kit as per sig, processed in Pixinsight.  Only managed to get 9 frames in because dawn broke.

The processing is the result of a monumental battle against noise, here's what the initial raw frames looked like:

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I'm not really sure why it was so revoltingly noisy to start with - I guess it's a fairly faint object, but then at mag 8 it's not *that faint, about the same magnitude as the dumbbell nebula which I've had much less noisy shots of.  Guess I'll need to do longer exposures, higher ISO and many more frames next time.

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Nice final image.

I would guess though that on your original RAW image that if you increase the ISO and do longer exposures then it will probably get just as much noise. The true photons that it captures will be brighter but so will the noise increase. As the ISO isn't that great I would suspect that it may be LP on those darker areas.

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That is a triumph of processing, well done. Nice final image. I have no idea why the subs are so noisy, though it could just be the seeing that was dodgy. Also, you say these were shot shortly before dawn, that could be the issue? If shot in full darkness, the results would probably be less noisy?

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nice one, looking forward to attempting this one myself. Can I ask, did you have to wait until the early hours for it to rise up away from the horizon?

Also what focal length was that done at?

keep up the good work.

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nice one, looking forward to attempting this one myself. Can I ask, did you have to wait until the early hours for it to rise up away from the horizon?

Also what focal length was that done at?

keep up the good work.

nah, long story, basically my kit is all in Spain and I had a weekend to try to do some AP - a couple of aborted evenings due to cloud so I bit the bullet and set the alarm for 4am.  So a race against the sun to get everything set up, focused, guiding and shooting before dawn - I must be crazy.

Focal length 750mm, aperture 150mm reflector, DSLR at prime focus.  Could have probably used a barlow tbh as the target was pretty small in the frame.

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