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About the Swift Gamma-Ray Burst Mission
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:
- Determine the origin of gamma-ray bursts.
- Classify gamma-ray bursts and search for new types.
- Determine how the burst evolves and interacts with the
- Use gamma-ray bursts to study the early universe.
- Perform the first sensitive hard X-ray survey of the
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
- ∼100 GRBs discovered per year
- 0.5-5 arcsec positions for almost every GRB
- Multiwavelength observatory (gamma-ray, X-ray, UV and
- <∼90 s reaction time for X-ray and UV/optical
- Spectroscopy from 180-600 nm and 0.3-150 keV
- Six colors covering 180-600 nm
- Results publicly distributed within seconds
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
- 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.
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
Key Info and Documents