Having some issues with Settling After the Dither

I’m using PHD2 multistar with a CDK14 and L-350 Planewave Mount. I often have the guiding fail to settle within a couple of minutes. It would be easy to assume this is bad seeing and/or the mount “ringing” from the pulses after the dither, but I’m having this during sessions with seeing measured at 1" and below and when I watch the encoder errors I see no vibration.

When I look at the guiding setup options I have currently got the Dither max error at 1.2 pixels, Minimum settle time at 10 seconds and Timeout at 120 seconds.

Is the 1.2 pixel max error referring to the guide camera’s image scale (which is .5" for me) and if so, is it referring to the unbinned image scale or the binned image scale (I am binning 2x2)? If it is referring to the binned guider image scale that would be a tolerance of 1.2" which is very high and if it is referring to the unbinned image scale it would still be .6" which is much higher than my typical guide error once settled.

I also can’t seem to understand how Voyager is determining that the guider has settled. During the settling after a dither I often see the guide star within a .5" error and yet the exposure does not begin. Is Voyager using a moving average of the guide error to determine it is settled? Or is it simply any guide error after the dither that is within tolerance?


Kevin Morefield

Answer is easy.
Error is espressed in pixel and refer to guide error reported by the guiding system. The error is relative on how you are shot for guiding and coming directly for the guiding system , Voyager do anything about in terms of calculations.

Dithering is declared finished when the error is equal or lower than the maximum value allowed continuosly for the settle time requested, one value greater than restart the time count. No average or mobile average is used, this will not have sense because is the peak that ruins the sub.

All the best

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