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IOK-1 by the Subaru Telescope
Observation data (J2000 epoch)
ConstellationComa Berenices
Right ascension13h 23m 59.8s
Declination+27° 24′ 56″
Distance12.88 billion light-years (3.95 Gpc)
Apparent magnitude (V)24.4

IOK-1 is a distant galaxy in the constellation Coma Berenices. When discovered in 2006, it was the oldest and most distant galaxy ever found, at redshift 6.96.[1]

It was discovered in April 2006 by Masanori Iye at National Astronomical Observatory of Japan using the Subaru Telescope in Hawaii and seen as it was 12.88 billion years ago. Its emission of Lyman alpha radiation has a redshift of 6.96, corresponding to just 750 million years after the Big Bang. While some scientists have claimed other objects (such as Abell 1835 IR1916) to be even older, the IOK-1's age and composition have been more reliably established.[2][3]

"IOK" stands for the observers' names Iye, Ota, and Kashikawa.

See also[edit]


  1. ^ Hogan, Jenny (2006), "Journey to the birth of the Universe", Nature, 443 (7108): 128–129, Bibcode:2006Natur.443..128H, doi:10.1038/443128a, PMID 16971914
  2. ^ Iye, Masanori; Ota, Kazuaki; Kashikawa, Nobunari; Furusawa, Hisanori; Hashimoto, Tetsuya; Hattori, Takashi; Matsuda, Yuichi; Morokuma, Tomoki; Ouchi, Masami; et al. (2006), "A galaxy at a redshift z = 6.96", Nature, 443 (7108): 186–188, arXiv:astro-ph/0609393v1, Bibcode:2006Natur.443..186I, doi:10.1038/nature05104, PMID 16971942
  3. ^ Press release, National Astronomical Observatory of Japan, September 13, 2006
Preceded by
SDF J132522.3+273520
Most distant astronomical object
Succeeded by
GRB 090423
Preceded by
SDF J132522.3+273520
Most distant galaxy
Succeeded by