Orbit Stability at BESSY

Traditionally, intrinsic component stability as well as perturbation source identification and suppression (like set-up modifications or feed-forward compensations) have been the preferred methods used to guarantee beam orbit stability for user operation at BESSY. The second focus of activity is the reliability of slow drift control and the high degree of beam position reproducibility maintained under frequently changed operation conditions. Along these lines, an overviewof the measures taken, the available diagnostic means as well as the achievements and shortcomings of the existing slow orbit feedback is given. Diagnostic capabilities of a fast BPM read-out and data distribution system give insight into the demands on a fast orbit feedback that could provide better operational flexibility and improved performance.