1. Guiding Control Subsystem (GCS) Overview 10-04-2006

2. Tasks Provide information to the PCS to identify tracking errors Provide information to PSF to compensate for basic wavefront distortions (active optics). Provide an interface for TCS and humans to select a proper guide star

3. Activities Control AutoGuider and Wavefront sensing (AGw)units (MODS, AIP & PEPSI AGw) Control AzCam guiding and WFS cameras Acquire and analyze camera images calculate centroid of GS and Zernike polynomial coefficients describing the Wavefront frequently send results to PSF and PCS subsystem

4. GUI provide different views for engineers and astronomers designed mainly for the needs of astronomers and telescope operators graphically keep track of the centroids and WF development over time major redesign of the GUI coming soon

5. Communication GCSsubsystem AGw control computer AGw hardware AzCam server Windows XP AzCam server Windows XP Guide Cam WFS Cam.... for each AGw unit PCS PSF

6. PEPSI support PEPSI needs access to the images of the guide cam GCSsubsystem PEPSI control computer PEPSI hardware AzCam server Windows XP Guide Cam PCS PSF IIF IIF is used to request guide cam image Guide Pic PEPSI Instrument Request Pic

7. Guiding Details Two algorithms available to determine centroid Default is Gaussian Fit: very precise, not good with irregularly shaped objects or bad SNR Optionally, instrument or astronomer can select Center-of-Weight (CoW) algorithm CoW is very stable, disregards shape of object and works with very bad SNR

8. WFS Details algorithm just left prototype status and proved reliability under simulated conditions uses centroiding algorithm how to initialize the matrices with the necessary values is currently discussed with AIP AGw team details of implementation yet to be discussed, i.e. derotation, calibration with primary mirror, etc.

9. TCS interface currently only a very basic interface is implemented start / stop guiding and WFS, status data needs improvement in cooperation with TCS developers

10. Improvements Foreseeable is the need for guiding on moving objects issue has been raised with the AGw teams as neither OSU nor AIP have a solution for this yet agreed on first do guiding on static objects after that they want to check how their hardware can support the GCS with moving objects