Center the star on the calibration LED position. This position should have been determined ahead of time by inserting the calibration unit and marking the spot position with one of the guide camera cursors. Normally this position will be used as the center of the field for pointing and tracking the telescope. The coma can be removed manually by issuing xset and yset commands to the TCS or, if not too large, left to the wavefront analyzer. If secondary mirror corrections are enabled in hartpar , the active optics routines will adjust the telescope to remove focus errors and coma during the night.
Longer times average out the seeing more effectively.
Enable hartmannloop processing of the S-H images by issuing command sh 1 in the guide camera window if using the fine mask. Use sh 2 for the coarse mask. Command send transmits the current image to blinky for processing by hartmann or hartmannloop . The current file number and transmitted lines are displayed on the guider screen. The active optics displays should be monitored to catch problems during operation.