... Reference Data for Calibration and Tools . ... Missions . ... Reference files used by the ACS calibration pipeline (CALACS and Astrodrizzle) are updated on a regular basis. Current reference files can be retrieved from the HST archive, or downloaded directly from the jref directory. ... If you would like to receive an e-mail every time a new ACS reference file is delivered and the database is updated, you can subscribe to the acs_reffiles_upd mailing list. ... ACS HRC Earth Flat Reference Files . ...