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| Event type | Gamma-ray burst  |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h 46m 38s |
| Declination | −19° 35′ 16″ |
| Redshift | 1.255 |
| Other designations | GRB 020813, GRB 020813A |
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GRB 020813 was agamma-ray burst (GRB) that was detected on 13 August 2002 at 02:44UTC. A gamma-ray burst is a highlyluminous flash associated with an explosion in a distant galaxy and producinggamma rays, the most energetic form ofelectromagnetic radiation, and often followed by a longer-lived "afterglow" emitted at longer wavelengths (X-ray,ultraviolet,optical,infrared, andradio).
GRB 020813 was detected on 13 August 2002 02:44UTC by multiple instruments on theHigh Energy Transient Explorer. The burst lasted approximately 125 seconds. The initial position was estimated to be at aright ascension of19h 46m 38s and adeclination of −19° 35′ 16″.[1] In less than two hours after the burst had been detected, optical observations of the region were made with theKatzman Automatic Imaging Telescope which reveal the burst's optical afterglow.[2] In the days following the event, observations were made by theChandra X-ray Observatory, which detected a fading X-ray afterglow.[3] Theredshift for this event was approximately z = 1.254.[4]
Previous to this burst, there had not yet been any concrete evidence linkinggamma-ray bursts tosupernovae, though it had long been hypothesized that the two phenomena were results of the same type of event. The spectrum ofGRB 011211 was reported to includeemission lines associated with thechemical elements magnesium, silicon, sulphur, argon, and calcium, which supported the theory that gamma-ray bursts are preceded by highly massive stars undergoing asupernova 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 casesulphur andsilicon.[6] This evidence confirmed the connection between supernovae and gamma-ray bursts.[7][8]