MDM Trouble Report for 2016 May 12

Telescope: 2.4m
Observer(s): Jianfeng Wu (University of Michigan)
Instrument: OSMOS/B

Problem(s) Encountered:
When switching target, I needed to change the rotator angle from -44.9 to 90.8. I was using the hand paddle to change the angle in the dome. When the angle increased to around 20 deg, the number in the display suddenly change to around -600 deg. Tried rotating in both directions, it appeared to hit a limit when the number is -558. Rotating back, the number suddenly changed to normal. Thus did not seriously affect observing. 

Checked trouble report archive, this situation happened before. The solution is similar. 

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Submitted on 2016 May 13 [6:26:51]