Astroart Forum

Hi there,
Last night when I try guiding through AA5 I experienced something interesting - the guide star I marked drifted out of the frame after about 20 seconds when guiding actually started, i.e. after calibration and after I hit the 'Mark star' button. Apparently AA5 tried to move the star back, but just couldn't.
It may seem to be a scope connection problem but the strange thing is, it happened *after* the calibration, since AA5 calibrated just fine(no complaints) so the scope connection must be good , isn't it?

No matter what I tried (restart AA5, park scope and reconnect, etc.), this problem persisted for about 20 minutes and magically went away - guiding is performed as expected... my scope didn't cross meridian for the time being, it was on the same side. I continued my imaging session for about 4 hours since after, and the guiding was like flawless...

I know my polar alignment was good enough since I did 3 iterations using AlignMaster. Guide camera is Lodestar X2 (AA5 driver DLL) and scope connection is ASCOM/EQMOD. Windows XP 32-bit.

Anyone had similar issue before? Could this be just some kind of software glitch, or physical like how my scope was balanced?

Thanks,
Yue

Hi,
during those 20 minutes, were you able to calibrate again? The result of the calibration was almost the same?

I thought I was able to calibrate during that 20 minutes and the star kept drifting.
However, last night I noticed another strange behavior right after activated the guiding - i'm not sure how to describe it properly but the guide star was 'circling' around the big green cross hair. In about 20-30 minutes I was able to re-calibrated a few times but couldn't get rid of the 'circling' movement - it happens after I hit 'Mark Star' ; then again it went back to normal and the guiding was again almost perfect for about 2 hours till the end of my imaging session.
I noticed when this happens my scope was very close to meridian - maybe I just shouldn't pick a star near meridian to calibrate?

Yue

Maybe backlash in RA? Because the scope was in position where it starts "pulling" in RA instead of "pushing"? I admit that this is unlikely, but you could verify the clutch and/or balancing better the scope. By the way, note somewhere the "correct" calibration (speed X and Y) and verify that they don't change too much on different nights.

Thanks Fabio. Yeah, it could be the backlash. I'll keep my eye on the calibration settings.
Also I think I can pick a star that not close to meridian, calibrate the guiding, then slew to the actual object I want to imaging without re-calibrating - if it's on the same side of meridian.