Main problems

There was no fault, or a number fault reports caused by the same problem that caused more than 2 hours downtime during period 48.

However, we have had various issues with the alignment of the secondary after the aluminisation. The secondary mirror unit has a tilt mechanism to align it properly with the optical axis of the system, and a displacement mechanism that corrects for the flexure of the telescope as a function of zenith distance. When remounting the mirror we had some problems installing it properly, which likely damaged the displacement mechanism, and caused some misalignment of the mirror unit. This has caused some minor degradation of the image quality under the best seeing conditions, and caused some misalignment in the pointing which is mostly an inconvenience. The main issue has been that we have had a lot of problems with identifying the precise problem, and correcting this. We do believe that we recently have successfully corrected the tilt of the secondary unit, but we are not sure if there is still an issue with the displacement mechanism as the poor weather has not allowed us to check things properly over the last couple of weeks. In any case, we now have a good idea of where any remaining problems might be, and how to solve this, and as soon as we have sufficiently good weather we should be able to confirm if the system is fully functioning, or if still some more work is needed.

Thomas Augusteijn 2016-05-05