Temporal optical behavior of HST: focus, coma, and astigmatism history

摘要

The focus of the Hubble Space Telescope (HST) has been monitored throughout the life of the observatory primarily by phase retrieval techniques. This method generates and fits model Point Spread Functions (PSFs) to nearly in-focus stellar images to solve for coefficients of the Zernike polynomials describing focus, and often coma and astigmatism. Here, we discuss what these data from the ongoing monitoring strategies and special observations tell us about modes and timescales observed in HST optical variations.