The Hubble eXtreme Deep Field (annotated)

This image, called the Hubble eXtreme Deep Field (XDF), combines Hubble observations taken over the past decade of a small patch of sky in the constellation of Fornax. With a total of over two million seconds of exposure time, it is the deepest image of the Universe ever made, combining data from previous images including the Hubble Ultra Deep Field of 2002/3 and Hubble Ultra Deep Field infrared image of 2009.

The image covers an area less than a tenth of the width of the full Moon, making it just a 30 millionth of the whole sky. Yet even in this tiny fraction of the sky, the long exposure reveals about 5500 galaxies, some of them so distant we see them when the Universe was less than 5% of its current age.

The Hubble eXtreme Deep Field image contains several of the most distant objects ever identified.

Among these are:

• UDFj-39546284, at a redshift of 10.3, is a candidate for the most distant galaxy yet discovered, though it is awaiting spectroscopic confirmation
• Supernova Primo, at a redshift of 1.55, the most distant type Ia supernova ever observed
• UDFy-38135539, at a redshift of 8.6, is the most distant galaxy to have had its distance independently corroborated with spectroscopy
• UDFy-33436598, at a redshift of 8.6