Spikes in DEC #guiding #Guiding

Sébastien Doré

Hello all, 

I'm having some spikes in my DEC guiding at times tonight. The worst ones seem to occur at periodic interval around 20-25 seconds but not all the time. Like about a dozen times in 400s periods. RMS values are good but DEC is about 40% bigger than RA because of these excursions. 

Conditions are fairly good now. No wind at all. Balance was quite accurate (as far as my eye can tell) in both RA and DEC. PA error reported by PHD2 is below 5 arc-min. I have a NUC on top of OTA, so no cable snag possible. Seeing is fair at 3.5-4".

My setup:
-EdgeHD 800 reduced to 1400mm FL
-Guide cam pixel scale : 1.7"/px
-Guiding through OAG at 3-4 seconds interval

Imaging M106 which is about 2hrs past meridian at the time of writing this.

That said, I'm not that familiar with guiding at such focal length... Any thoughts on what might be causing this ?


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