The Swift Gamma-Ray Burst Mission

Swift satellite artists conception Gamma-ray bursts (GRBs) are the most powerful explosions the Universe has seen since the Big Bang. They occur approximately once per day and are brief, but intense, flashes of gamma radiation. They come from all different directions of the sky and last from a few milliseconds to a few hundred seconds. So far scientists do not know what causes them. Do they signal the birth of a black hole in a massive stellar explosion? Are they the product of the collision of two neutron stars? Or is it some other exotic phenomenon that causes these bursts?

With Swift, a NASA mission with international participation, scientists will now have a tool dedicated to answering these questions and solving the gamma-ray burst mystery. Its three instruments will give scientists the ability to scrutinize gamma-ray bursts like never before. Within seconds of detecting a burst, Swift will relay a burst's location to ground stations, allowing both ground-based and space-based telescopes around the world the opportunity to observe the burst's afterglow. 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.

Swift Makes Best-ever Ultraviolet Portrait of Andromeda Galaxy
UVOT Mosaic of M31

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Latest Swift Gamma-Ray Bursts
Latest Swift News
  • Swift Returns to Normal Operations (2009 Sep 22)
    As of 16:30 UT 2009 Sep-22, Swift is back to normal operations (GCN Circular 9928).

  • BAT and UVOT Temporarily Off-line (2009 Sep 18
    Due to a software problem, the BAT instrument stopped processing science data at about 10:30 UT on 2009 Sept. 17 (GCN Circular 9922). As a consequence BAT is not detecting new GRBs at this time, and UVOT is not making observation. XRT is largely unaffected and continues to observe the usual schedule of pre-planned targets. The BAT problem is understood, and we expect to restore Swift to normal operations in a few days.

  • Swift Makes Best-ever Ultraviolet Portrait of Andromeda Galaxy (2009 Sep 16) Shown on this page.
    In a break from its usual task of searching for distant cosmic explosions, NASA's Swift satellite has acquired the highest-resolution view of a neighboring spiral galaxy ever attained in the ultraviolet SEE BELOW! ! The galaxy, known as M31 in the constellation Andromeda, is the largest and closest spiral galaxy to our own at 2.5 Million Light Years away.                  
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    The Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on 2004 November 20 , UTC 17:16:00 on the Delta II 7320-10C series expendable launch vehicle. Swift is managed by the NASA Goddard Space Flight Center, was developed by an international consortium from the United States, United Kingdom, and Italy and is part of NASA's Medium Explorer Program (MIDEX).




    Swift is a multi-wavelength space-based observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments work together to observe GRBs and their afterglows in the gamma-ray, X-ray, ultraviolet, and optical wavebands.

    Based on continuous scans of the area of the sky which one of the instruments monitors, Swift uses momentum wheels to autonomously slew into the direction of possible GRBs. The mission's name "Swift" is not an acronym, but rather refers to this rapid slew capability and the nimble bird of the same name.[2] All discoveries of Swift are quickly sent to the ground and those data are available to other observatories which join Swift in observing the GRBs.

    In the time between GRB events, Swift is available for other science and scientists can submit proposals for observations.

    The Swift Mission Operation Center (MOC), where commanding of the satellite is performed, is located in State College, Pennsylvania and operated by the Pennsylvania State University and industry subcontractors. The Swift main ground station is located in Malindi on the coast of Eastern Kenya, Africa and is operated by the Italian Space Agency. The Swift Science Data Center (SDC) and archive are located at the Goddard Space Flight Center. The UK Swift Science Data Centre is located at the University of Leicester.

    The Swift spacecraft bus was built by Spectrum Astro, which was later acquired by General Dynamics Advanced Information Systems.[3]


     Burst Alert Telescope (BAT)

    The BAT detects GRBs events and computes its coordinates in the sky. It covers a large fraction of the sky (over one steradian fully coded, three steradians partially coded -- by comparison, the full sky solid angle is 4π or about 12.6 steradians). It locates the position of each event with an accuracy of 1 to 4 arc-minutes within 15 seconds. This crude position is immediately relayed to the ground and some wide-field, rapid-slew ground telescopes can catch the GRB with this information. BAT uses a coded-aperture mask of 52,000 randomly placed 5 mm lead tiles, 1 metre above a detector plane of 32,768 4 mm CdZnTe hard X-ray detector tiles; it is purpose-built for Swift. Energy range: 15 - 150 keV.[4]

     X-ray Telescope (XRT)

    The XRT can take images and perform spectral analyses of the GRB afterglow. This provides more precise location of the GRB, with an error circle of approximately 3.5 arcseconds radius. The XRT is also used to perform long term monitoring of GRB afterglow light-curves for days to weeks, depending on the brightness of the afterglow. The XRT is primarily composed of the X-ray mirrors from the JET-X mission, with the detector upgraded to a single MOS CCD similar to those used by the XMM-Newton EPIC MOS cameras. Energy range: 0.2 - 10 keV.[5]

     Ultraviolet/Optical Telescope (UVOT)

    After Swift has slewed towards an GRB, the UVOT is used to detect an optical afterglow. UVOT provides a sub-arcsecond resolution position and provides photometry through lenticular filters in optical and ultra-violet and spectra (170–650 nm) through the use of its optical and UV grisms. UVOT is also used to provide long time follow-ups of afterglow lightcurves. UVOT is based on the XMM-Newton mission's Optical Monitor (OM) instrument, with upgraded onboard processing computers.[6]

     Science goals

    • Determine the origin of GRBs. There seem to be at least two types of GRBs, only one of which can be explained with a hypernova, creating a gamma-ray beam. More data is needed to explore other explanations.
    • GRBs seem to take place at "cosmological distances," which means they can be used to probe the distant, and therefore young, universe.
    • The all-sky survey will be more sensitive than any previous one, and will add significantly to our knowledge of astronomical X-ray sources. Thus, it could also yield unexpected results.
    • Swift is also utilized as a general purpose gamma-ray/X-ray/optical observatory platform, performing rapid "Target of Opportunity" observations of many transient astrophysical phenomena, such as supernovae.

      Mission progress

    UVOT "first light" picture
    • Swift was launched on November 20, 2004, and reached a near-perfect orbit of 586x601 km altitude with an inclination of 20°.
    • On December 4, an anomaly occurred during instrument activation when the Thermo-Electric Cooler (TEC) Power Supply for the X-Ray Telescope did not turn on as expected. The XRT Team at Leicester and Penn State University was able to determine on December 8 that the XRT would be usable even without the TEC being operational. Additional testing on December 16 did not yield any further information as to the cause of the anomaly.
    • December 17 at 07:28:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located on-board an apparent gamma-ray burst during launch and early operations.[7] The spacecraft did not autonomously slew to the burst since normal operation had not yet begun, and autonomous slewing was not yet enabled.
    • Swift had its first GRB trigger during a period when the autonomous slewing was enabled on January 17, 2005, at about 12:55 UT. It pointed the XRT telescope to the on-board computed coordinates and observed a bright source in the field of view.
    • On February 1, 2005 the mission team released the "first light" picture of the UVOT instrument and declared Swift operational.
    • As of April, 2009, Swift has detected more than 400 GRBs and X-ray afterglows for more than 90% them, and optical afterglows for more than 50% of them.

      Mission status

    • On May 9, 2005, Swift detected GRB 050509b, a burst of gamma rays that lasted one-twentieth of a second. The detection marks the first time that the location of a short-duration gamma-ray burst has been identified.
    • On September 4, 2005, Swift detected GRB 050904 with a redshift value of 6.29 and a duration of 200 seconds (most of the detected bursts last about 10 seconds). It was also found to be the most distant at approximately 12.6 billion light years.
    • On February 18, 2006, Swift detected GRB 060218, an unusually long (about 2000 seconds) and nearby (about 440 million light years) burst which was unusually dim despite its close distance, and may be an indication of an imminent supernova.
    • On June 14, 2006, Swift detected GRB 060614, a burst of gamma rays that lasted 102 seconds in a distant galaxy (about 1,6 Billion light years). No supernova was seen following this event (and GRB 060505 to deep limits) leading some to speculate that it represented a new class of progenitors. Others suggested that these events could have been massive star deaths, but ones which produced too little radioactive 56Ni to power a supernova explosion.
    • On March 19, 2008, Swift detected GRB 080319B, a burst of gamma rays amongst the brightest celestial objects ever witnessed. At a distance of 7.5 Billion light years, it established a new record for farthest object (briefly) visible to the naked eye. It is also said to be 2.5 million times intrinsically brighter than the previous brightest accepted supernova.[8]
    • On that same day, Swift observed a record four GRBs, hence the "B" suffix indicating the record burst was the second. Incidentally, as noted by NASA's press release, this happened quickly after the death of noted science-fiction writer Arthur C. Clarke.
    • On January 9, 2008, Swift was observing a supernova in NGC 2770 when it witnessed an X-ray burst coming from the same galaxy. The source of this burst was found to be the beginning of another supernova, later called SN 2008D. Never before had a supernova been seen at such an early stage in its evolution. Following this stroke of luck (position, time, most appropriate instruments), astronomers were able to study in detail this Type Ibc supernova with the Hubble Space Telescope, the Chandra X-ray Observatory, the Very Large Array in New Mexico, the Gemini North telescope in Hawaii, Gemini South in Chile, the Keck I telescope in Hawaii, the 1.3m PAIRITEL telescope at Mt Hopkins, the 200-inch and 60-inch telescopes at the Palomar Observatory in California, and the 3.5-meter telescope at the Apache Point Observatory in New Mexico. The significance of this supernova was likened by discovery team leader Dr. Alicia Soderberg to that of the Rosetta Stone for egyptology.[9]
    • On February 8 and February 13, 2008, Swift provided critical information about the nature of Hanny's Voorwerp, mainly the absence of an ionizing source within the voorwerp or in the neighboring IC 2497.
    • On 23 April 2009, Swift detected GRB 090423, the most distant cosmic explosion ever seen at that time, at a distance of 13.035 billion light-years. In other words, the universe was 630 million years old when this burst occurred.[10]


    1. ^ "NASA Swift Mission Extended for 4 More Years". Omitron. http://www.omitron.com/headlines/hl05.htm. Retrieved 2008-04-07. 
    2. ^ J.D. Myers (26-Sep-2007). "Swift Guest Investigator Program Frequently Asked Questions". NASA/ GSFC. http://swift.gsfc.nasa.gov/docs/swift/swiftfaq.html#name. Retrieved 2009-05-02. 
    3. ^ "Swift". Spectrum Astro. http://www.spectrumastro.com/AIS/gprod/content/detail.cfm?item=ba5f3851-5741-405f-b617-943e4191e88f. 
    4. ^ J.D. Myers (28-Feb-2006). "Swift's Burst Alert Telescope (BAT)". NASA/ GSFC. http://swift.gsfc.nasa.gov/docs/swift/about_swift/bat_desc.html. Retrieved 2009-05-02. 
    5. ^ J.D. Myers (15-Aug-2008). "Swift's X-Ray Telescope (XRT)". NASA/ GSFC. http://swift.gsfc.nasa.gov/docs/swift/about_swift/xrt_desc.html. Retrieved 2009-05-02. 
    6. ^ J.D. Myers (14-Dec-2006). "Swift's Ultraviolet/Optical Telescope (UVOT)". NASA / GSFC. http://swift.gsfc.nasa.gov/docs/swift/about_swift/uvot_desc.html. Retrieved 2009-05-02. 
    7. ^ Ed Fenimore (17 December 2004). "GRB041217: The First GRB Located On-Board Swift". LANL. http://gcn.gsfc.nasa.gov/other/041217.gcn3. Retrieved 2009-05-02. 
    8. ^ J.D. Harrington, NASA Goddard Space Flight Center (03.20.08). "NASA Satellite Detects Naked-Eye Explosion Halfway Across Universe". Press release. http://www.nasa.gov/centers/goddard/news/topstory/2008/brightest_grb.html. Retrieved 2009-05-02. 
    9. ^ Robert Naeye, NASA Goddard Space Flight Center (05.21.08). "NASA's Swift Satellite Catches a Star Going 'Kaboom!'". Press release. http://www.nasa.gov/mission_pages/swift/bursts/swift_supernova.html. Retrieved 2009-05-02. 
    10. ^ Francis Reddy, NASA Goddard Space Flight Center (04.28.09). "New Gamma-Ray Burst Smashes Cosmic Distance Record". Press release. http://www.nasa.gov/mission_pages/swift/bursts/cosmic_record.html. Retrieved 2009-05-02. 

      External links

    Swift Gamma-Ray Burst Mission
    General information
    NSSDC ID 2004-047A
    Organization NASA/Goddard Space Flight Center
    Major contractors Spectrum Astro
    Launch date 2004-11-20 17:16:00 UTC
    Launched from Space Launch Complex 17
    Cape Canaveral Air Force Station
    Launch vehicle Delta II 7320-10C
    Mission length 6 years [1]
    (4 years, 10 months, and 26 days elapsed as of 2009 Oct 16)
    Mass 1470.0 kg
    Orbit height 600 km
    Orbit period ~ 90 minutes
    Telescope style coded mask (BAT)
    Wolter I (XRT)
    Ritchey-Chrétien (UVOT)
    Wavelength γ-ray / X-ray / UV / Visible
    Diameter 30 cm (UVOT)
    Collecting area 5,200 cm² (BAT)
    Focal length 381 cm (UVOT)

    BAT Burst Alert (gamma-ray) Telescope
    XRT X-Ray Telescope
    UVOT UltraViolet / Optical telescope
    Website http://swift.gsfc.nasa.gov

    Ultraviolet Andromeda ( From the APOD for 2009 Sept 17)
    Credit: UV - NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)
    Optical - Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF

    Explanation of Photo Below: Taken by a telescope onboard NASA's Swift satellite, this stunning vista represents the highest resolution image ever made of the Andromeda Galaxy (aka M31) - at ultraviolet wavelengths. The mosaic is composed of 330 individual images covering a region 200,000 light-years wide. It shows about 20,000 sources, dominated by hot, young stars and dense star clusters that radiate strongly in energetic ultraviolet light. Of course, the Andromeda Galaxy is the closest large spiral galaxy to our own Milky Way, at a distance of some 2.5 million light-years. To compare this gorgeous island universe's appearance in optical light with its ultraviolet portrait, just slide your cursor over the image.

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