Multidrizzle and Tweakshifts: Overview and Future Plans

The MultiDrizzle software provides a flexible, unified interface to the various steps involved in registering, cleaning and combining dithered HST data. MultiDrizzle can be run on ACS, WFPC2, NICMOS and STIS imaging data in a single step, with default parameters chosen to provide good results for the majority of datasets if standard recommended dithering patterns were followed. Alternatively, the various parameters can be adjusted and specific steps can be run one at a time for additional flexibility, if desired for certain scientific applications. MultiDrizzle has also been incorporated into the HST OTFR pipeline for ACS data, thereby allowing automatic delivery of cleaned, combined data that can be used directly for science in many cases, or alternatively used as a baseline for re-running MultiDrizzle offline using customized parameters, if required for certain scientific applications. Here we review the basic fundamentals of dithering, together with the current status of MultiDrizzle and describe plans for future related pipeline enhancements, including the Tweakshifts shift-refinement script.