Quote:
Originally Posted by Joshua Bunn
What kind of ADU do you get on your guide star?
The profile of the star in your picture shows 2 spikes, maybe there is some confusion as to which "spike" should be followed? but then i guess this problem would also be on the RA axis.
Ive never tried to see how long i could go without Dec drift, but while doing my PEC log, the guide star doesnt move (except for PE), as i too have excellent PA, and with your PA you would be able to track for a long time (sorry about the subjectivity) without drift. Your issue isn't Dec drift IMO.
As Roger says, i would look at your Dec drift without guiding corrections to try and isolate things, weather its mechanical or a guiding related issue.
What does the Dec guiding graph look like as time goes on? Does it keep oscillating?
Josh
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Hi Josh,
I appreciate your comments.
I have long understood the need for good star focus and saturation. The exposures in the photo posted above were 4 seconds. The double spike is caused by infra red passing though my APO and then through the ONAG to the ST-i. As you say, if the double spike were causing this I'd see it also in RA. I don't.
The reason I was asking about declination drift is that a post at SB suggested that maybe my aggression setting was too low and the mount just couldn't keep up with the declination drift. As I mentioned it usually only happens after a few minutes of quite good guiding. The suddeness is surprising when it happens. Perhaps if I could increase aggression in declination only I could control this. But, getting stuck on both sides of "Y" makes little sense unless something mechanical is slipping.
Anyway, tonight I will devote time to seeing what is happening without guiding corrections.
Thanks,
Peter