Celestial hemisphere:  Northern  ·  Constellation: Canes Venatici (CVn)  ·  Contains:  IC 4263  ·  M 51  ·  NGC 5169  ·  NGC 5194  ·  NGC 5195  ·  NGC 5198  ·  NGC 5229  ·  Whirlpool galaxy
M51 - first try, Dan Phillips
M51 - first try
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M51 - first try

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Description

Another hard test for the motorized barn door tracker. As usual I had to throw out about 50% of the exposures, but my rate-tracking code adjustment is reasonably close, so the dominant factors are now getting precise polar alignment and mechanical problems from stress of the weight of the ST80 and my poor ball-mount attachment. That's limiting me to 30" exposures with the small telescope.

Still struggling with periodic error. It seems to be coming from the cheap plastic gears. Since the longest gear period is just 60 seconds and there are shorter gear periods with visible error signals, I may need to replace the whole drive system to do better ... or give up trying to use the barn door mount with the ST80! But my results are still pretty satisfying despite the frustrating process. I could try to implement PEC with the arduino code, but it's not clear enough of the error would be reliably repeatable for that to be worth the bother.

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M51 - first try, Dan Phillips