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About the Swift Gamma-Ray Burst Mission

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Introduction to Swift

Swift is a first-of-its-kind multi-wavelength observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments work together to observe GRBs and afterglows in the gamma-ray, X-ray, ultraviolet, and optical wavebands. The main mission objectives for Swift are to:

Swift discovers approximately 100 bursts per year. The Burst Alert Telescope detects GRBs and accurately determines their positions on the sky. Swift then relays a 3 arcminute position estimate to the ground within 20 seconds of the initial detection. The spacecraft "swiftly" (in less than approximately 90 seconds) and autonomously repoints itself to bring the burst location within the field of view of the sensitive narrow-field X-ray and UV/optical telescopes to observe the afterglow. In addition to an accurate position, Swift provides multi-wavelength lightcurves for the duration of the afterglow, a gamma-ray spectrum of the burst, X-ray spectra of the afterglow, and in some cases can constrain the redshift of the burst.

Swift measurements are of great interest to the astronomical community and all data products are available to the public via the internet as soon as they are processed. The Swift mission represents the most comprehensive study of GRB afterglows to date.

Swift is part of NASA's medium explorer (MIDEX) program and was launched into a low-Earth orbit on a Delta 7320 rocket on November 20, 2004. The instruments were developed by an international team from the United States, the United Kingdom, and Italy, with additional scientific involvement in France, Japan, Germany, Denmark, Spain, and South Africa.

Swift Science and Instruments

Baseline Capabilites:

The Swift telescope payload is comprised of three instruments which work in tandem to provide rapid identification and multiwavelength follow-up of gamma-ray bursts (GRBs) and their afterglows.

Burst Alert Telescope (BAT): 15 - 150 keV
With its large field-of-view (2 steradians) and high sensitivity, the BAT detects about 100 GRBs per year, and computes burst positions onboard the satellite with arc-minute positional accuracy. The BAT was been produced by the Astrophysics Science Division at NASA's Goddard Space Flight Center (GSFC) with science flight software developed by the Los Alamos National Laboratory.
X-ray Telescope (XRT): 0.3 - 10 keV
The XRT was built using (in part) existing hardware from JET-X. The XRT takes images and is able to obtain spectra of GRB afterglows during pointed follow-up observations. The images are used for higher accuracy position localizations, while light curves are used to study flaring and the long-term decay of the X-ray aferglow. The XRT is a joint product of the Pennsylvania State University, the Brera Astronomical Observatory (OAB), and the University of Leicester.
UV/Optical Telescope (UVOT): 170 - 600 nm
The UVOT is essentially a copy of the XMM-Newton Optical Monitor (OM). The UVOT takes images and can obtain spectra (via a grism filter) of GRB afterglows during pointed follow-up observations. The images are used for 0.5 arcsecond position localizations and following the temporal evolution of the UV/optical afterglow. Spectra can be taken for the brightest UV/optical afterglows, which can then be used to determine the redshift via the obsered wavelength of the Lyman-alpha cut-off. The UVOT is a joint product of the Pennsylvania State University and the Mullard Space Science Laboratory (MSSL).

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