HST/ACS Associations: the Next Step after WFPC2

After the release of the successful WFPC2 associations, the CADC, ST-ECF and STScI are now working on joint pipeline software to produce associations of images from the HST’s Advanced Camera for Surveys instrument. Although the basic approach is very similar to the WFPC2 associations (Durand et al., 2004) there are some fundamental differences because of the high level of geometric distortion of the ACS optics. The core of the ACS association pipeline will perform image combination using the Drizzle method and hence there will be no need to constrain the position angle of associated observations as was done with WFPC2. Our goals are the production of high quality products for the HST archive users and eventual ‘publication’ of these products within the Virtual Observatory.