JSkyCalc-xtcs Coordinate Input Confusion

Saturday, May 27, 2017 9:50 AM

Problem(s) Encountered:

The trouble began when an incorrect position was used to reset the RA/Dec encoders.  The telescope ended up in the hard limits.  Not only that, but the usual procedure to ease out of the limit (hold start button and set button and direction simultaneously) didn''t work.  The TCS wouldn''t accept any input.  So I restarted the TCS program, and was then able to ease out of the limit.  All operations were normal after that.  Including having to reset

pointing using the tilt meters, 1.5 hours was lost.  It was a good lesson, however.

This is the exact problem that was discussed in a trouble report of 2016 April 4.  It is caused by using JSkyCalc to supply a next object position, under the assumption that this position will be used to reset the encoders.  That assumption is not correct.  It is the position in the xtcs GUI that is used to reset the encoders, whether or not that position was ever sent to the TCS.  IMHO, it is an awkward design flaw to have two different methods to send a next object position to the TCS that don''t behave the same way in all respects.  If there were only only way to send a next object position, this problem could not occur.


Yup -- that can happen.  Given that the entire system is about to be replaced, it may not worth fixing at this point.

If it''s easy enough to fix, I suppose I could.  I don''t know if the xtcs allows an external command to set the ''next object'' position in the gui, but I can look into it next month when I''m out there. [Thorstensen]