Improvements in Monitoring and Reconstructing HST’s ACS/WFC Charge Transfer Efficiency Losses

Radiation damage to the Hubble Space Telescope's ACS/WFC CCD detectors results in steadily worsening charge transfer efficiency (CTE). Our internal monitoring program designed to track CTE degradation relies on Extended Pixel Edge Response (EPER) data. We summarize updates to the observing techniques and analysis of the EPER data, and present CTE monitoring results over the lifetime of ACS. In addition, new post-flashed calibration data to inform the pixel-based CTE model were recently obtained. We present our updates to the model's parameters using these data, and evaluate the pixel-based CTE corrections applied to HST's ACS calibration and science data resulting from these updates.