1ES 1927+654

1ES 1927+654 is a type 2 Seyfert galaxy located 270 million light-years away in the constellation of Draco, containing an active galactic nucleus. The galaxy is relatively unremarkable in appearance but its core is powered by a supermassive black hole which is a source of X-ray flashes.

The brightness and oscillations of this nucleus have behaved unpredictably and so become the subject of special observation and study in the optical, radio, ultraviolet and X-ray spectrums. Academic papers analysing its unusual characteristics have challenged conventional theories about accretion disks and black hole environments.

1ES 1927+654 is the catalog reference for the object in the Einstein Slew Survey – a scan of the sky in the X-ray spectrum which was performed by the Einstein Observatory and first published in 1992.