[Comm2011] Log 2011-08-01; astrometry/rotator

[Konrad Kuijken]

The snow melted away, the wind dropped, the temperature went up to a toasty 10 degrees, and we have been open since about 10pm.
Main priority was to get the automatic acquisition of guide stars to work. 

In the process of that we may have found why the astrometric solutions just would not converge. There appears to be a 1-deg backlash in the instrument rotator of the vst, which means that depending on the direction of motion the sky orientation can differ by a degree. No wonder it was turning out to be difficult to predict where the guide stars would fall! Half the time the solution was good, half the time the errors in the predicted positions were over 100 pixels.

An unpleasant surprise, but progress nonetheless. Pietro and Javier are working on a solution... let's see.

K