QSO J0439+1634,[4] often referred to by just its coordinates, J0439+1634 or J043947.08+163415.7,[1] is a superluminous quasar, and was, until 20 February 2024, (when it was superseded by QSO J0529-4351) considered the brightest quasar in the early universe with a redshift of z = 6.51.

[5][2][6][7] It is approximately 12.873 billion light-years away.

[1][3] The brightness of the quasar is equivalent to about 600 trillion luminosities of the Suns with gravitational lensing, without this effect 11 trillion.

[5][6][3] The quasar-related supermassive black hole has a mass of 700 million solar masses.

[7][8] On April 3, 2018, the ACS/WFC observed and photographed gravitational lensing at the location of the quasar, and further research revealed an extremely bright and large quasar there.