Problem(s) Encountered:

Apparently, there is a problem with the TC>IC link, which manifested itself in a rather interesting way.

Operations went perfectly smoothly, until around UT 07:00, when the program we use to get the objects into the slit (osctrtask on a pyraf session on /hiltner) started complaining, and ultimately aborting with the following error message :

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Exception in Tkinter callback

Traceback (most recent call last):

 File  /usr/lib/python2.3/lib-tk/Tkinter.py , line 1345, in __call__

   return self.func(*args)

 File  /usr/local/pkg/lib/python/pyraf/epar.py , line 789, in execute

   self.runTask()

 File  /usr/local/pkg/lib/python/pyraf/epar.py , line 1041, in runTask

   self.taskObject.run(mode=''h'', _save=1)

 File  /usr/local/pkg/lib/python/pyraf/iraftask.py , line 271, in run

   self._run(redirKW, specialKW)

 File  /usr/local/pkg/lib/python/pyraf/iraftask.py , line 1074, in _run

   apply(self._pyFunction, pl)

 File  osctrtask.py , line 259, in osctrtask

   obsep, rotangle = biasquads(acqroot, acqimage )

 File  osctrtask.py , line 165, in biasquads

   rastr, decstr, eqstr, rotangstr, filtid2str, objectstr, exptimestr, datestr, timestr, jdstr = hselout[0].split('''')

ValueError: unpack list of wrong size

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I looked at the FITS headers for the files in questions, but could at first glance not find what may have been wrong in those compared to the ones used just before that error message.

Everything else behaved totally normally, and there were no apparent warning signs that something with the TCS link may have gone awry.

Since I was able to circumvent the problem of not being able to use this specific tool for slit alignment, I simply began jogging  the objects into the slit manually, and encountered no other problems.

However, when towards the end of the night, I looked over the TCS agent console messages, I found out that ever since then error messages like the following had occured :OUT: TC>IC DONE: TCSLINK=Down DATE-OBS=2015-11-14 TIME-OBS=14:37:40.654

TIMESYS=UTC JD=2457341.109498 MJD=57340.609498

It hence seems that the TCS server does not communicate with IC. Restarting the TCS PC (as per the description provided) successfully brought that PC back into normal operation mode (which had not been affected anyway), but the TCSLink remains down. The Prospero Status window, however, shows both TC : Up + TCSLink in green (and hence I did not check the TC>IC communication earlier, as I had no indication that the problem could be rooted there).

The red power supply indicator lamp on the TCS Power rack has begun

flickering.....

Before messing unneccesarily in my tired state with this, I have decided to leave the problem alone (also because the weather forecast predicts two nights of almost zero chance to observe).

Solutions:

Logged in and saw the errors in the TCS Agent Console terminal. Performed a “Clear Link” in the TCS GUI (under <<Setup>>, then issued a tcinit followed by a tcstatus in the TCS agent console terminal.  Doing the tcstatus issued current and correct header info.  Did a test scan via prospero and checked header information.  Saw no errors and the header looks fine.  Additionally, the TCS Agent Console terminal indicates tc=active now instead of the erroneous tc=down previously.

Incidentally, the light on the TCS power supply, in the computer room, does tend to blink.  This is normal.  There is no need to power cycle the TCS.  In fact, I wouldn’t recommend ever power-cycling it without it being a last resort (or imminent storms).