Platform motion as ch goes 2 to 20 degrees



    All previous pointing models have been made with the carriage house (ch) at stow position (za=8.84 degrees). When the dome is at a large za and passes in front of a tower the tie down cables go slack causing a problem with the pointing. If we moved the rest position of the carriage house up to say 18 degrees za then the tie down cables would not go slack as quickly. For this to work we need to check:
  1. How much "temperature range" will  we gain by moving the ch up to 18 degrees. How much will this lift the dome side.
  2. The path of the dome will now follow a different track in focus. Will this make the current focus error better or worse?
  3. The azimuth rails were shimmed with the ch at 8.84 degrees. Will moving out to 18 degrees affect things like the 3 azimuth term?

The setup:

The computations and plots:

    The plot shows the results of the computations (.ps) (.pdf).


    When the dome points at a corner:  
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