How it would look in our night sky if this J2157 replaced Sagittarius A*
SMSS J215728.21-360215.1, commonly known as J2157, is one of the fastest growing black holes and one of the most powerful quasars known to exist as of 2018. The quasar is located at redshift 4.75, corresponding to a comoving distance of 25×109 ly from Earth and to a light-travel distance of 12.5×109 ly. It was discovered with the SkyMapper telescope at Australian National University's Siding Spring Observatory, announced in May 2018. It has an intrinsic bolometric luminosity of 6.95×1014 L☉ (2.66×1041 W).
In July 2020 the black hole associated with the quasar was reported to be 34 billion solar masses, based on a study about to be published in Monthly Notices of the Royal Astronomical Society.