A gamma-ray burst is a highly luminous flash associated with an explosion in a distant galaxy and producing gamma rays, the most energetic form of electromagnetic radiation, and often followed by a longer-lived "afterglow" emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, and radio).

GRB 020813 was detected on 13 August 2002 02:44 UTC by multiple instruments on the High Energy Transient Explorer.

The spectrum of GRB 011211 was reported to include emission lines associated with the chemical elements magnesium, silicon, sulphur, argon, and calcium, which supported the theory that gamma-ray bursts are preceded by highly massive stars undergoing a supernova collapse.

[5] However, these results were considered statistically insignificant and somewhat controversial due to the low resolution of the instruments used.

[6] The spectrum of GRB 020813 was also found to display emission lines of elements associated with supernovae, in this case sulphur and silicon.