List of most luminous stars

This cannot be observed directly, so instead must be calculated from the apparent magnitude (the brightness as seen from Earth), the distance to each star, and a correction for interstellar extinction.

Some suspected binaries in this magnitude range are excluded because there is insufficient information about the luminosity of the individual components.

The first star in the list, Godzilla[1] — an LBV in the distant Sunburst galaxy — is probably the brightest star ever observed, although it is believed to be undergoing a temporary episode of increased luminosity that has lasted at least seven years, in a similar manner to the Great Eruption of Eta Carinae that was witnessed in the 19th century.

In terms of gamma rays, a magnetar (type of neutron star) called SGR 1806−20, had an extreme burst reach Earth on 27 December 2004.

It was the brightest event known to have impacted this planet from an origin outside the Solar System; if these gamma rays were visible, with an absolute magnitude of approximately −29, it would have been brighter than the Sun[dubious – discuss] (as measured by the Swift spacecraft).

The gamma-ray burst GRB 971214 measured in 1998 was at the time thought to be the most energetic event in the observable universe, with the equivalent energy of several hundred supernovae.