Hubble Deep Field

The Hubble Deep Field (HDF) is an image of a small region of the sky (a survey field, within the constellation Ursa Major) taken over a very long exposure, using the Hubble Space Telescope (HST), aiming to image as distant galaxies as possible.

• right ascension: 12h36m49.4000s
• declination: +62deg12m58.000s
• Size: 2.6' × 2.6' (~6.75 square arcminutes)
• Exposure: on the order of 4 days
• Date: December 1995

The HDF was an experiment and not everyone anticipated it would be worth HST's valuable time, but its data did support much useful scientific study. This subsequent study included observation of the same region with in other EMR bands (radio, infrared, etc.) for additional understanding of the imaged objects. With the HDF's value established, similar efforts have been carried out (some with the HST and some with other telescopes) for other portions of the sky, including the Hubble Deep Field South (HDF-S) in 1998, the Hubble Ultra-Deep Field (HUDF) in 2003/2004, and the Hubble Extreme Deep Field (HXDF or XDF) in 2012.