At a redshift z = 6.6,[1] the galaxy is observed as it was about 800 million years after the Big Bang, during the epoch of reionisation.

[1] With a light travel time of 12.9 billion years, it is one of the oldest, most distant galaxies known.

[3] However, recent studies show no evidence for population III stars in CR7.

[6] Galaxy Cosmos Redshift 7 contains old Population II (metal-poor) and possibly Population III (stars with extremely poor metallicity), according to astronomers,[1][2] and is three times brighter than the brightest distant galaxies (redshift, z > 6)[1][7] detected up to the time of its discovery.

[3][5] Astronomers led by David Sobral, a Reader in Astrophysics at the University of Lancaster, used the Very Large Telescope (VLT) at the European Southern Observatory—with help from the W. M. Keck Observatory, Subaru Telescope and the NASA/ESA Hubble Space Telescope—made the discovery.