Astrodrizzle: Advanced Camera for Surveys Mosaic of the Sombrero Galaxy M104

We present an example of a high-level science product created using AstroDrizzle, a new task that replaces MultiDrizzle. AstroDrizzle is one of several tasks in the new AstroDither package that replaces the Dither package. A mosaic of M104 (the Sombrero galaxy) was created from ACS WFC images of 24 overlapping fields at 6 pointings to form a combined image that reveals fine details of the galaxy's edge-on grandeur. In this example, we emphasize use of the tweakreg task, also in the AstroDither package, that provides a semi-automated interface for computing offsets between input images that will be combined using AstroDrizzle. Much of the same algorithmic base used in MultiDrizzle is maintained in AstroDrizzle. However, AstroDrizzle employs a fundamentally different approach to handling image distortions and astrometry based entirely on FITS WCS conventions that simplifies data analysis efforts (see Fruchter et al., AAS January 2012). It also provides slightly better cosmic ray rejection, and fixes several bugs in MultiDrizzle. For additional information about the AstroDither package, please refer to the 'AstroDrizzle Handbook,' available at http://www.stsci.edu/hst/HST_overview/documents.