It is the deepest image of the universe ever taken , looking back approximately NUMBER@1 billion years , and it will be used to search for galaxies that existed between NUMBER@2 and NUMBER@3 million years after the Big Bang .

It is the deepest image of the universe ever taken by Hubble , looking back -LRB- to when the universe is thought to have been NUMBER@3 million years old -RRB- approximately NUMBER@1 billion years ago .
