GRB 020813 was a

gamma-ray burst In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten millise ...

(GRB) that was detected on 13 August 2002 at 02:44 UTC. A gamma-ray burst is a highly luminous flash associated with an explosion in a distant galaxy and producing

gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...

s, the most energetic form of

electromagnetic radiation In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) li ...

, and often followed by a longer-lived "afterglow" emitted at longer wavelengths (

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

, and

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmi ...

Observations

GRB 020813 was detected on 13 August 2002 02:44 UTC by multiple instruments on the High Energy Transient Explorer. The burst lasted approximately 125 seconds. The initial position was estimated to be at a right ascension of and a declination of . In less than two hours after the burst had been detected, optical observations of the region were made with the

Katzman Automatic Imaging Telescope The Katzman Automatic Imaging Telescope (KAIT) is an automated telescope used in the search for supernovae. The telescope had a first light in 1998, and is a noted robotic telescope. It had first recorded data in August 1996, and was formally de ...

which reveal the burst's optical afterglow. In the days following the event, observations were made by the

Chandra X-ray Observatory The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the during STS-93 by NASA on July 23, 1999. Chandra is sensitive to X-ray sources 1 ...

, which detected a fading X-ray afterglow. The redshift for this event was approximately z = 1.254.

Supernova relation

Previous to this burst, there had not yet been any concrete evidence linking

s to supernovae, though it had long been hypothesized that the two phenomena were results of the same type of event. The spectrum of GRB 011211 was reported to include

emission lines A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...

associated with the

chemical element A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...

s magnesium, silicon, sulphur, argon, and calcium, which supported the theory that gamma-ray bursts are preceded by highly massive stars undergoing a supernova collapse. However, these results were considered statistically insignificant and somewhat controversial due to the low resolution of the instruments used. The spectrum of GRB 020813 was also found to display emission lines of elements associated with supernovae, in this case sulphur and

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ta ...

. This evidence confirmed the connection between supernovae and gamma-ray bursts.

References

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External links

HETE Trigger Summary
020813 20020813 August 2002 events