GRB 000131

GRB 000131

Event type	Gamma-ray burst
Constellation	Carina
Redshift	4.5 ±0.1, 4.5
Other designations	GRB 000131
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GRB 000131 was a gamma-ray burst (GRB) that was detected on 31 January 2000 at 14:59 UTC. 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 000131 was detected on 31 January 2000 at 14:59 UTC by Ulysses, KONUS, NEAR Shoemaker, and BATSE. It lasted approximately 90 seconds.^[1] The initial position, derived from the observations of all the aforementioned spacecraft, was estimated at a right ascension of 6^h 13^m 32.72^s and a declination of −51° 55′ 36.77″.^[2] On 4 February 2000, optical observations of the region were made by telescopes at Paranal Observatory and La Silla Observatory in Chile which revealed the burst's optical afterglow.^[3]

GRB 000131 had a redshift of approximately z = 4.5.^[4] This corresponds to a distance of about 11 billion light years, making it the most distant gamma-ray burst that had ever been recorded up to that date.^[5] This distance record was broken by GRB 050904, which had a redshift of z = 6.29.^[6][7]

GRB 000131 was the first gamma-ray burst to have its optical afterglow detected by an 8-meter telescope. At the time of its discovery, GRB 000131 was the most distant burst ever detected. However, it was not the most energetic: assuming isotropic emission, the total energy output of the burst was approximately 10⁵⁴ ergs, placing it in second behind GRB 990123. Furthermore, the gamma-ray data also suggested that the burst was beamed rather than isotropic, a characteristic which would further decrease the total energy output. This demonstrated the importance of the use of optical telescopes in the studies of gamma-ray bursts.^[8]