CALACS: The Seventeen Year Evolution of a Space Telescope Data Pipeline
After 17 years in orbit, two electronics failures, a mid-life servicing mission in 2009, and numerous updates to the used reference files and codebase of its data pipeline, many aspects of the calibration plan for the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) have changed since its initial design concept prior to launch in early 2002. In this poster, we will discuss the challenges inherent to calibrating and maintaining multiple detectors (two CCDs and a MAMA) in a Low-Earth Orbit radiation environment for an extended period using a single calibration package. In addition, during the ACS lifetime there have been both changes in the operation of the instrument (e.g., a reduction in operating temperature in 2006) and innovations to long-standing problems (e.g., a correction model for charge-transfer efficiency loss) that have required changes to how we calibrate ACS data. The nearly-constantly accessible sky has also dictated scheduling requirements for how we obtain ACS calibration data between regular annealing periods. Finally, we will also show how the ACS calibration code compares to the other active HST instruments in its design and implementation in the automated HST data processing pipeline before data are stored in the data archive.
