Dropleaf/Slit Control Failure (and revisiting 12 minutes in HA)

Thursday, June 6, 2019 1:34 PM

Problem(s) Encountered:

Dropleaf doesn't close at the end of the night.  The TCS log behaves as if it did close, giving no error message. I restarted the telescope program and the TCS GUI, to no avail. The dome is in the home position.  I didn't try to close the main slit, as I am not sure what else might happen if I do. The mirror cover is closed.

Another issue is that the telescope pointing is off by 12 minutes of time, a rare but recurrent problem, when I first sent it to zenith. When I send the telescope to zenith again, it is now pointing 3 degrees east, which is the same as 12 minutes of time. 


The bracket for the magnetic dome “home” arm (on rotating portion of dome) had come loose causing it to hang down and come into contact with the magnetic sensor (on static portion of dome) and its mount prematurely.  This meant that the contacts weren’t properly seating so there was no power to the dropleaf (or shutter) motors.  Bracket has been tightened and reshaped.  I think it had just come loose over time through vibrations as the dome turns.  Still, ran the dome a full 360º to check for any obstructions.  All looks well.  Tony will fabricate an additional L-bracket to further support the arm in hopes of eliminating the possibility of this happening again.
The 12 minutes in HA is a mystery to me.  It’s been reported to Treffers, but I have gotten no response about it.  The occurrence of this pointing offset, as far as I can tell, only happens when the telescope servers are reset (telescope stop/telescope start).  Any time this hopefully at some point this will be resolved, but for now it is a mystery within software.