The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area about 2.6 arcminutes on a side, about one 24-millionth of the whole sky, which is equivalent in angular size to a tennis ball at a distance of 100 metres. The image was assembled from 342 separate exposures taken with the Space Telescope's Wide Field and Planetary Camera 2 over ten consecutive days between December 18 and 28, 1995.
The Hubble Deep Field
The dramatic improvement in Hubble's imaging capabilities after corrective optics were installed encouraged attempts to obtain very deep images of distant galaxies.
Diagram illustrating comparative sampling distance of the HDF and the 2004 Hubble Ultra-Deep Field
A section of the HDF about 14 arcseconds across in each of the four wavelengths used to construct the final version: 300 nm (top left), 450 nm (top right), 606 nm (bottom left) and 814 nm (bottom right)
Ursa Major is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater bear", referring to and contrasting it with nearby Ursa Minor, the lesser bear. In antiquity, it was one of the original 48 constellations listed by Ptolemy in the 2nd century AD, drawing on earlier works by Greek, Egyptian, Babylonian, and Assyrian astronomers. Today it is the third largest of the 88 modern constellations.
Ursa Major
The constellation Ursa Major as it can be seen by the unaided eye
Ursa Major and Ursa Minor in relation to Polaris
The Pinwheel Galaxy
