The Hubble Deep Field, Ultra-Deep Field, and eXtreme Deep Field
On January 15, 1996, NASA released to the public one of the most extraordinary astronomical images of all time. The Hubble Deep Field (Fig. 7.1), a composite of 342 separate WFPC2 exposures taken from December 18–28, 1995, covered an area of the sky of only 2.5 arc-minutes, and is located in a nearly featureless area in Ursa Major (Fig. 7.2).