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M51: B&W


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Well I've now got the M51 data to process and I'm quite pleased..

This is a stack of the best 100 images, all 5second subs. So total imaging time is still only about 8 minutes.

Sadly I lost about 300 frames due to misting up and another 100 when a neighbours searchlight sneaked in a crack in the dewshield.

Really must get myself a heater to stop the dew.

I used darks, biases and flats to maximise the sensitivity, each one from a stack of 16 frames.

This just goes to show how bright M51 is.

Other details:

Camera: Lodestar

Scope: 12"f5 newt

mount: Fullerscope MKIV

Filters: None

thanks for looking



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That truely is splendid! I like it a lot... 5 sec subs, blimey, I was having to use 30 sec with my ST120... mind you, I'm guessing the camera had something to do with it too ;-)



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  • 1 month later...

I had a go at re-processing this one. I'm now much more happy with it as I've managed to maintain the core detail, show up a bit more in the arms and still see the background. I also magaged to manipulate the FWHM down to about 1.7 arc seconds by enlarging all the subs 2x2 pre-stacking, not bad for 1.1 arc second pixels. I don't know who exactly Richarson or Lucy are, but their deconvolution algorithum is very useful.


Processed in IRIS:

1. sub bias & dark (mostly bias with 5 second subs)

2. divide by flat.

3. double size

4. order subs by best strehl ratio.

5. coregister (multistar automatic registration) first 90% of images (best 90% by strehl)

6. statistically stack, removing outlying pixels limit set to +/-3 sigma from average, removes all sorts of muck.. including satellites, hot pixels and cosmic rays.

7. deconvolve using a large number of gentle itterations.

8. subtract what's left of the sky.

9. play with curves. logs etc.

10. crop flip / rotate.


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