Coordinates: 3h 32m 39.0s, −27° 47′ 29.1″
The Hubble Ultra-Deep Field (HUDF) is an image of a small region of space in the constellation Fornax, containing an estimated 10,000 galaxies. It is composited from Hubble Space Telescope data accumulated over a period from September 24, 2003, through to January 16, 2004. Looking back approximately 13 billion years (between 400 and 800 million years after the Big Bang) it has been used to search for galaxies that existed at that time. The HUDF image was taken in a section of the sky with a low density of bright stars in the near-field, allowing much better viewing of dimmer, more distant objects. In August and September 2009, the Hubble's Deep Field was expanded using the infrared channel of the recently attached Wide Field Camera 3 (WFC3). When combined with existing HUDF data, astronomers were able to identify a new list of potentially very distant galaxies.
Located southwest of Orion in the southern-hemisphere constellation Fornax, the rectangular image is 2.4 arcminutes to an edge, or 3.4 arcminutes diagonally. This is approximately one tenth of the angular diameter of a full moon viewed from Earth (which is less than 34 arcminutes), smaller than a 1 mm by 1 mm square of paper held at 1 meter away, and equal to roughly one thirteen-millionth of the total area of the sky. The image is oriented so that the upper left corner points toward north (−46.4°) on the celestial sphere.