[g__day (Matthew)]

I decided to do my last play with MaxPoint before I swapped to Tpoint. I improved the backlash in my DEC gears then did a three star alignment on the SkySensor2000-PC (Fomalhaut, Dipha and Rigel Kentarus) - which I re-tested and found very accurate gotos.

So I ended up performing a 162 star alignment and saw very interesting behaviours. I slowly swept around the sky - starting in the South East and heading North.

By 30 stars the pointing error (corrected) was an impressive 35 arc seconds, but as I slowly swept around to different quadrants of sky the tracking each new quadrant seemed off by a consistent amount in a new direction. By 100 stars the pointing error (corrected) was 1.8 arc minutes. It stayed like this up to 162 stars covering the full night sky.

The tracking errors seem quadrant based to me (forming almost a H pattern). So I am pondering if this is most likely a slight mirror shift (using a C9.25 SCT) in each new quadrant of the sky?

The raw pointing in each quadrant of the sky seems very consistent. I am hoping that Tpoint is smart in how in addresses point errors - by adjusting for pointing by deciding the correction required using those points closest to the target. Is this the case anyone?

Thanks, Matt