... HST Overview . ... Target Location in Aperture / 32-1 . ... Calibration Accuracies / 32-5 . ... Below we first address important factors affecting various calibration accuracies and the data quality (e.g., target centering, mechanism repeatabilities, and image location). Then we discuss the limitations associated with each type of FOS calibration and their associated impact on FOS data quality, providing information to help you estimate the accuracy in your particular science observations. ...