MDM Trouble Report for 2025 Jan 17

Telescope: 1.3m
Observer(s): John Thorstensen (Dartmouth)
Instrument: Templeton direct

Problem(s) Encountered:
I finished on an equatorial target and then tried to move to 
another target at +74d 24'; after a moment the slew status field 
on JSkyCalc13mGS turned red with  Slew ERROR , and the tracking
turned off.  The target was still over 4h E -- which I thought
was within limits, but I wasn't certain, so I did another target
for a while, and then returned to it when it was about 2h E. 

Same problem! So I set on another target north of +70, but south
of the one I wanted -- it was fine.  Still got an error when I 
tried the desired target, though.  I then tried sneaking up on
it and got to over +73, and tried hopping north in 60  increments
using the paddle -- but that didn't work, either -- the telescope
started moving in dec (perhaps the tracking turned off) and 
refused to continue north. (I also tried re-entering the coords
in JSkyCalc by hand, in case there was some invisible bad char
in the coordinate string).  

Then I tried moving with commands from the MDM13 control system -
 point ra=10:01:33 dec=+74:24:45 , or actually the J2025 coords,
since the TCS lives in the present -- and got a POINT error
briefly in the status page, 

Error point illegal Dec90

and when I played around with it and tried something a bit 
farther north still,  Error point illegal Dec91 .

At this point the only thing I could think to do was to bring
down the interface program, so I went to the zenith, exited 
from the MDM 1.3 TCS program (and from JSkyCalc), which did 
not fix the problem, so I acquired a secondary target for the
rest of the night. 

A couple of things to note -- one can get a slew error if one
tries to slew to a target with the telescope tracking off. I was
aware of that and turned the tracking back on before attempting
to slew, so that wasn't the problem.

Also, the telescope had no trouble acquiring targets elsewhere,
before or after I tried to get the +74 target. The pointing 
remained good all night. 

On thinking about it I suppose I could have tried intentionally 
resetting the encoders to read 1 degree south of their true 
position, but that seems rather desperate.

I am sure I have observed targets this far north in the past,
and this was many hours east of the pier tripwire ...

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Submitted on 2025 Jan 18 [7:48:54]