March 9, 2004

Hubble Ultra-Deep Field

Astronomers unveil the Hubble Ultra Deep Field

Light from the faintest objects in the image arrived at roughly one photon per minute. Hubble circled Earth 400 times to collect it.

9 March 2004: 10,000 galaxies in a keyhole

The Space Telescope Science Institute publicly unveiled the Hubble Ultra Deep Field on 9 March 2004, and NASA issued its release the same day. The field showed an estimated 10,000 galaxies in a patch of the constellation Fornax only about one-tenth the apparent diameter of the full Moon.

The release combined an extremely deep visible-light image from Hubble's Advanced Camera for Surveys with a separate near-infrared view from NICMOS. Light from the faintest detected objects arrived at about one photon per minute.

800 exposures, 400 orbits

The ACS image was built from 800 exposures through four filters — F435W, F606W, F775W and F850LP — over 400 Hubble orbits of director's discretionary time. Total exposure came to 11.3 days, roughly one million seconds, gathered between 24 September 2003 and 16 January 2004 across about 11 square arcminutes.

STScI director Steven Beckwith was principal investigator and committed the orbits; Massimo Stiavelli led the project, and Anton Koekemoer assembled the final ACS image from the individual exposures.

Toothpicks and bracelet links

The image exposed a population of irregular early galaxies, described in the release as resembling toothpicks or links on a bracelet, very unlike familiar mature spirals and ellipticals.

The ACS view reached galaxies from about 800 million years after the Big Bang. NASA said NICMOS might have detected candidates from about 400 million years after the Big Bang, but Rodger Thompson, the NICMOS principal investigator, cautioned that those required follow-up confirmation.

Sources

Researched 23 Aug 2026 8 sources 2 audit passes

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What the sources leave uncertain

The March 9 release date is confirmed independently by NASA’s contemporary release and its Hubble science timeline.
In 2004, objects placed about 400 million years after the Big Bang were tentative NICMOS candidates, not confirmed galaxies. The more secure ACS reach was about 800 million years after the Big Bang.
“One million seconds” is a rounded description; NASA separately gives the accumulated exposure as 11.3 days.