TCS Pointing/hiltner Timestamp Issue

Thursday, August 24, 2017 1:00 PM

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.


I set the time and also changed the time zone (was set to NYC,NY, now set to PHX,AZ).  Lastly, I verified that ntp is running.  NTPD synchronization fails on boot, but then the next step passes, which is to start the ntpd.  Not sure why they are ordered that way.  Still, doing a ntpq -p and a ntpstat appear to indicate that ntpd is running correctly.  Also, rebooted the machine and ensured that the correct time remained.  Lastly, Rick Pogge (OSU) updated NTP config to match mcgraw, David Will and Pogge found a wrong entry in the /etc/sysconfig/network/ifcfg-eth0 file giving the wrong gateway, and the /etc/resolv.conf was updated to match mcgraw. Once we restarted the network, ntpd synched with the KPNO Stratum 0 servers.