Balance

The telescope rotator has been balanced with ALFOSC, NOTCam and MOSCA by using an arm mounted with the instrument. This arm extends about one meter and has weights mounted at the end. This balances out the uneven weight distribution on the adapter and the instruments. The advantage is that we do not risk any rotator runaways at accidental power losses which can harm the rotator tachometers. The rotator brakes can now hold these instruments at any rotator position and altitude. There is still a tube unbalance which makes the tube want to go upwards at low altitudes and downwards at high altitudes. This is not critical and does not significantly reduce the altitude tracking accuracy. A possible way to correct this has been designed but we still are considering if this is worth the effort.

It has happened more than once that after an instrument change the setting for the moveable counterweight on the telescope were not changed. A way to provide some short of check on this is to include a check of the counterweight setting when the instrument-name is set in the TCS to one of the instruments mounted at the Cassegrain focus. A warning should be given if the position of the counterweight is found to be significantly different from the default value.