EBZ 26 Dec 96 - with input from CED and JFC Summer 96
EBZ 18 Jul 2000

				  ISS LOOP
				  --------



				 EXPLANATION

- ISS reads in limb of sun and automatically centers the instrument (active 
  optics). It is a feedback loop. It works when the loop is closed, and 
  doesn't work when open.


				  PROCEDURE

- Open the ISS (Image Stabilization System) loop before doing anything that 
  could go out of the normal range of the instrument because if the loop is 
  closed and the ranges are exceeded damage could be done.  To close the loop
  and make sure that is is properly set up, a separate procedure has to be run.

  To open the loop, use the procedure q_openloop_v#.src (# is the lastest 
  version)

  To close the loop and make sure that is is properly set up, a separate 
  procedure has to be run: alignit_v#.src 

- When the FOT closes the loop using our TSTOL to do so, the allowable
  limits for the x and y averages are between 1.5 and 3.5.