Rotator

The major problem with the brushes of one of the rotator motors described above, was the first time these brushes failed since the telescope was assembled. One of the reasons why it took a lot of work to replace the brushes, was that dissembling the rotator and the motor was not done before, and turned out to be very cumbersome. However, the process itself was better understood, and some specialised tools were made to make this task easier so that on a future occasion a similar problem can be resolved in much less time.

As the rotator motors are constantly used in-tandem, it was decided to also check the brushes of the second motor, also giving a chance to try the new tools. We also planned to order a new spare set of brushes, but they turned out to be rather expensive. It was decided to try to repair the broken set of brushes, and try them in the second motor when it would be disassembled to check the state of the brushes. This was recently done, and the brushes in the second motor were in a much better state that those of the motor that failed, but still one of the brushes was close to being worn out, and after a successful test we left the repaired brushes mounted in the second motor. At the moment we are repairing this second set of brushes to have a working spare.

The rotator has a full range of about 400 degrees, that means that a position within 40 degrees from an end stop has a corresponding position 360 degrees away that gives the same field rotation. In some cases it could be preferred to have the rotator positioned for longest possible following of an object (e.g., for a planet transit observation). Normally the rotator goes the shortest way to the destination position. An option has been implemented so that if the reference position ends up within 40 degrees from an end stop it can be adjusted with 360 degrees to give longest possible following of an object when presetting the telescope.