Montage: A Grid Enabled Image Mosaic Service for the National Virtual Observatory

The architecture of Montage, which delivers custom science-grade astronomical images, was presented at ADASS XII. That architecture has been tested on 2MASS images computed on single processor Linux machines that hold all image data in memory. This year, we describe the design of a grid-enabled version of Montage, suitable for large scale processing of the sky. It exploits to the maximum the parallelization inherent in the Montage architecture, whereby image reprojections are performed in parallel. All the re-projection jobs can be added to a pool of tasks and performed by as many processors as are available. We show how we can describe the Montage application in terms of an abstract workflow so that a planning tool such as Pegasus can derive an executable workflow that can be run in the Grid environment. The execution of the workflow is performed by the workflow manager DAGMan and the associated Condor-G. The grid processing will support tiling of images to a manageable size when the input images can no longer be held in memory. When fully tested, Montage will ultimately run operationally on the Teragrid. We will present processing metrics and describe how Montage is being used, including its application to science product generation by SIRTF Legacy Program teams and large-scale image processing projects such as Atlasmaker (this conference).