AOS Stress Test Results

In an effort to move the full (5 term) AOS system closer to "always on" readiness as series of stress tests were performed on Jan. 24, 2013.

If the AOS system cannot determine a hexapod correction with uncertainty less than 300 microns in dx and dy and uncertainty less than 30 arcseconds in tip and tilt, it simply sets the recommended hexapod correction to zero for all terms except focus. It also clears the PID integral terms so that if the system enters a long period of poor results, no hexapod corrections will be sent. AOS continues to monitor alignment and when conditions improve, hexapod updates begin anew.

Focus corrections are significantly more robust and will continue whenever they can be determined.

Situations known or expected to cause this failure mode include u-band exposures, low star counts, very short exposures, very high star counts. All of these situations were tested with results contained in the attached file.

Summary: the current AOS system can be enabled all the time and will either help keep DECam aligned or pause it's operations when it cannot.