A test sketch of M81

Friday night was clear with very good transparency.  I finished re-doing my TPoint calibration and, as part of that, confirmed that polar alignment is still good.  Then did a new, larger, data collection run for periodic error correction.  Something still not right there – the uncorrected error was higher than it should be (although not high).  Corrected it’s fine, but I still hope to get to the bottom of what’s going on there.

Autoguiding is also working fine now – not incorrectly calibrating on hot pixels – since I set up dark-frames and hot pixel elimination for the guide camera.

Messier 81

Messier 81

So, last thing before the sky went hazy, I did a test run of M81, just for fun.  This was 6 5-minute luminance frames.  Interesting: the mount is so stable with PEC and guiding running that I have a problem with dust spots that I’ve never had before.  In my former setup, the error and wobbling in the mount provided a sort of “auto-dither” that smeared out the noise (and the non-noise). Now it’s so stable that the pixel errors are always in exactly the same spot, and so are visible.  So, next time, I’ll start adding a several-pixel dither to the autoguiding.

Anyway, it’s a pretty image.  I think I’ll keep it, add data and colour, and work it into a finished product.  Not right away though: this object has almost rotated behind my tree, and I’ll soon lose it until autumn.

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