What's in a name? Many people have asked, "What does Swift stand for?" In truth it does not stand for anything. The "Swift" name is not an acronym. The observatory is actually named after a small, nimble bird, the same bird that appears in the Swift logo. The Swift observatory is built to be agile, quickly turning to point its instruments at gamma-ray bursts and relaying the burst locations to the ground within seconds, much like the Swift bird might grab up insects as it flies through the sky. Thus the Swift bird serves as a metaphor for the Swift observatory.

United States of America, United Kingdom, Italy

NASA Goddard Space Flight Center, USA (BAT instrument, Project Management), Penn State University, USA (XRT, UVOT, Operations), General Dynamics C4 Systems, and Spectrum Astro Space Systems (Spacecraft Vendor), University of Leicester, UK (X-ray Telescope and detectors), Mullard Space Science Lab, UK (UVOT Assembly), Brera Observatory (OAB), Italy (X-ray mirrors for the XRT), Italian Space Agency, Italy (Ground Station Support), Los Alamos National Laboratory, USA (BAT Instrument Flight Software), Sonoma State University, USA (Education and Public Outreach)

Principal Investigator: Neil Gehrels

2 years minimum.

Swift is an innovative mission designed specifically for GRB science. Swift's three instruments will work together to observe GRBs and afterglows in the gamma-ray, X-ray and optical wavebands. The Burst Alert Telescope (BAT) will monitor the entire sky to catch a GRB and calculate an initial position. Armed with the position, the Swift spacecraft will autonomously slew to bring the GRB into the Swift's X-Ray Telescope (XRT) and Ultra-Violet/Optical Telescope (UVOT) fields-of-view within 90 seconds. All three telescopes will watch the gamma-ray burst and afterglow unfold. Over the next several days Swift will return to the GRB to observe the afterglow's behavior over time.

Design: Swift is able to acquire a GRB's position with a pointing accuracy of 0.3 to 0.5 arcseconds. Swift can robotically reposition itself to point at the burst within 20 - 75 seconds.

Dimensions: 5.64 meters

Mass: 1470 kilograms

Swift has a complement of three instruments for studying gamma-ray bursts and their afterglow:

Swift Instrument Cooperation

Swift's three instruments work together to glean as much information about each burst as possible. Swift's multiwavelength observations of GRBs and afterglow are completely simultaneous. The XRT and UVOT have co-aligned fields-of-view, both falling within the BAT field-of-view, so that any source can be observed in all three wavebands.

When a GRB occurs, the BAT will be the first of Swift's instruments to detect it. Within about 10 seconds of the burst trigger, the BAT produces a burst localization, which is transmitted to ground observers. In addition, the BAT's position is fed to the Swift spacecraft so a slew can be performed, bringing the GRB into the XRT and UVOT's fields-of-view.

Within about 60 seconds of a burst trigger, the XRT refines the BAT position. The UVOT produces an even more accurate localization within about 200 seconds of the burst trigger. During all of this, the BAT continues observing the GRB to obtain a picture of how the gamma-ray emission evolves over time. X-ray spectra are distributed to the astronomical community after about 1200 seconds (20 minutes), and the UVOT filters complete their cycles after about 7200 seconds (2 hours). Together, these observations provide a clear picture of the GRB and its afterglow over time in three distinct wavebands.

While not engaged in observations of a new GRB, Swift's telescopes will perform preprogrammed observations, which include long-term follow-up of GRBs as well as other science.

Swift and Other Telescopes

Past and current advances in the understanding of gamma-ray bursts (GRBs) have come with the cooperation of many telescopes observing different wavebands. While Swift has the capability of making multiwavelength observations of GRBs, continued multiwavelength observations of GRBs by other telescopes is not only anticipated but is invaluable.

Swift facilitates community-wide contributions to GRB science in two ways. First, Swift disseminates GRB positions as soon as they are available. This allows operators of other satellite and ground-based telescopes to schedule immediate observations when feasible. Second, if a GRB is discovered by another telescope, the coordinates can be uploaded to Swift so that it can perform rapid observations of these bursts.

Swift is part of NASA's medium explorer (MIDEX) program. It was launched into a low-Earth orbit on a Delta 7320 rocket on November, 20 2004. During its nominal 2-year mission, Swift is expected to observe more than 200 bursts and afterglows, which will represent the most comprehensive study of GRB afterglows to date.