Reducing SOFIA's Image Jitter - an Ongoing Challenge

One of the most challenging engineering tasks at SOFIA is keeping the telescope stable, even during turbulent flight conditions. A conservative control system design was chosen to enable smooth operations and reach the requirements during SOFIA's early science phase. Now, fully operational and after several years of successful flights, increasing demands on the image size require further assessment of the pointing performance. The major portion of the remaining image motion is caused by deformation and excitation of the telescope structure in a wide range of frequencies due to aircraft motion and aero-acoustic effects. This talk presents the current pointing control system, recently implemented and in-flight tested upgrades as well as future improvement strategies.