MDM Trouble Report for 2017 Aug 24

Telescope: 2.4m
Observer(s): Thorstensen&Rupert (Dartmouth+MDM)
Instrument: OSMOS+B4K

Problem(s) Encountered:
Going to our first target we noticed that the pointing was 
wildly off, and the UT and sidereal time on the TCS were 
about 2 hours fast.  Repeated  Set UT  calls didn't change it.
We rebooted the TCS computer and tried again -- no luck.  We
got on the air by acquiring zenith with the tilt meters, then 
using the sidereal time from JSkyCalc to set the pointing, and 
(easily) acquiring a bright star.  

We observed all night with the telescope thinking it was 2 hours
west of where it was.  The main problem was that the dome's
computed position was wrong, so we had to move the dome by hand.

After we closed I realized what had happened -- Hiltner had
been swapped out the previous day, and when I checked the clock
on Hiltner it turned out to be almost 2 hours fast.  That's
why the set UT command had apparently failed -- it was simply
setting the TCS to HIltner's incorrect time.  A quick 
inspection showed that the time stamps on all the OSMOS 
images were also wrong, so they will have to be fixed in 
post-production, as the film industry people say.  

Eric reset the clock on Hiltner today and made sure it was on
ntp.  To close the loop it would be good to have some
idea of why this happened so we can be assured that Hiltner's 
clock will remain in synch.

------------------------------

Submitted on 2017 Aug 25 [12:01:00]