The above pictures illustrate how well GLAST will image the sky in comparison with EGRET. On the left is EGRET's resulting image of its last all sky survey. On the right is an image of the gamma-ray sky as seen by GLAST.
GLAST will be able to greatly improve the positions of sources of gamma-rays so that they may be more easily identified. Solving the puzzle of the unidentified sources (especially those that appear to be in our Galaxy) may be one of GLAST's biggest contributions.