Mirror Covers Fail to Open

Thursday, January 3, 2019 1:52 PM

Problem(s) Encountered:

...the mirror cover cannot be open. We can hear some sound, but the cover

simply does not stand up. We tried a few times, and it still cannot open, so have to stop observing. The instrument is not rotated back as the mirror cover cannot be open. We tried to open the mirror cover just about one hour before opening the dome, it works! It also worked when we rotating the instrument.


Tried the mirror covers when I arrived this morning.  They tried but failed.  Immediately noticed that they were closed in the wrong orientation, with the east and west petals both on top of the north and south petals (really wrong!).  I could not simultaneously lift up on both E/W petals to allow the N/S to open as I am here alone so far this week (Tony out sick), so I depressurized the system.  With air pressure removed from the equation, I tied open the west and east petals, then did the same with the north and south.  I then freed up and lowered the E/W petals followed by the N/S ones.  I then brought the pneumatic systems back up and tested the covers.  Cycling them a few times worked fine.  I also de-rotated the instrument (I hope the covers really were open all the way when it was rotated!).

This may have all stemmed from some ice in the lines as it’s been particularly cold (<0C) and wet (~5” snow) up here and the system had sat idle for many days.  I plan to drain the tanks shortly and will cycle the covers again later today.