Atmospheric dispersion corrector

A redesigned atmospheric dispersion corrector (ADC) was delivered from Denmark. Tests on the bench were done to verify operation and it seemed to work though some problems were encountered particularly with significant delays in the response of the program to the movement of the arm. The ADC was mounted in the adapter but when it was requested to move it failed. The ADC was then removed from the telescope and testing back on the bench found that one of the mechanical relays used to control the arm was sticking. Also during this test the spring plate used to move the arm broke off, probably due to fatigue. A new spring plate was designed and delivered by Niels Michaelsen (CUO) and modifications to the arm made to accommodate this. Because of the long delays of controlling the arm motion over an Internet connection it was decided to change the control of the arm motion to be directly operated through the TCS input/output system, making the timing much more accurate. After a closer look at the relay electronics board it was found that this could be replaced by a proper motor controller single integrated circuit. A new board has been design to do this. Also, all the electronics that were originally mounted on the ADC will be moved to a separate control box mounted outside the adapter to allow for easier access. It is hoped that the ADC can be installed again early next year.