Kevin_A #p69123 Hmmm, where did you see that, Kevin?
Oh, I see it now! My apologies. (I had to magnify and altered colors. 75 year od eyes that went through cataract surgery :-)
The pulses are indeed maxed out, but only after the oscillation has started. Since the amplitude of the oscillation are large (12 arcsecond region), any pulse durations would naturally be maxed out when trying to correct it.
But there is a latency too. Notice that it takes a couple of pulses before the oscillation changes sign again.
(With digital feedback loops, latency is a killer when it comes to introducing oscillations -- kinda like phase error in analog feedback loops.)
Looks like it takes three pulses to correct 12 arcseconds. Assuming those are 1 second pulses, each pulse is some 4 or so arcseconds (0.5x sidereal rate would be 7.5 arc seconds). Thus Max RA durations appears to be large.
@CHriss
Check your RA aggressiveness setting. Start at 0.15 (15% in ASIAIR) and only increase it slowly (and try not to increase it to more than 0.5) only when there is insufficient correction.
Are you using a Max RA duration of more than 1000 ms or a guide exposure that is longer than 1 second? The pulses appears to indicate that you perhaps did.
If so, start at a Max RA Duration of 100 ms. Increase it only if you see long combs of the correction pulses, and the RA is slowly creeping off the chart.
Then make sure that you are using guide exposures of 0.5 seconds (and checking that your guide camera can keep up with a 2 FPS frame rate). That will make corrections more rapid. That implies that you will need to use multi-star guiding (or the "seeing" will eat you alive).
However, a 0.5 second guide exposure may mean that you need to upgrade your guide scope to get solidly a dozen stars when picking the multiple stars.
If you are happy with a 1" type guiding, a 1 second guide exposure should be sufficient -- but that will still require you to use multi-star guiding with at least 6 stars.
Chen
