The ACS Exposure Time Calculator (ETC) is an on-line tool useful to predict the signal-to-noise for various observing modes, once the characteristics of the source are known.

Link to Current ETCs

Additional applications specific to the ACS are:

STSDAS

the IRAF package containing CALACS, which is used to process ACS data

Drizzle

the task under IRAF providing a robust method for combining images taken at different pointings into a final output mosaic product

MultiDrizzle

the PyRAF script that performs automated image registration, cosmic-ray rejection and final combination with drizzle, all in a single step, with user-adjustable parameters to provide more flexibility if desired.

OTFR

"on the fly reprocessing" is run automatically on data requested from the archive

AXE

For ACS slitless modes, a dedicated package has been developed by the ST-ECF to enable automatic and reliable extraction of large numbers of spectra.

Requests for ACS data from the HST Archive always return data reprocessed with the current version of CALACS and the best available reference files. In most cases it is easier to let the OTFR pipeline reprocess data for you. If standard pipeline processing is inadequate, however, CALACS may be downloaded and run locally.