Detecting powerful cosmic explosions

• The first observatory to study gamma ray bursts minutes after they occur
• A NASA mission with international collaboration including the UK and Italy
• Launched 20 November 2004

Gamma ray bursts are the most powerful explosions ever seen. Some of them are among the most distant objects in the Universe but their brightness allows scientists to study the conditions of the early Universe.

The gamma ray bursts last from fractions of a second to a few minutes and are thought to occur either when a massive star ends its life or when two dense neutron stars collide. Scientists believe these bursts may signal the birth of a black hole.

The afterglow contains less energetic forms of electromagnetic radiation (X-ray to radio waves) and can be seen fading for days or even weeks.

Mission facts

• Swifts detects around 100 gamma ray bursts per year.
  
  
• Swifts sends the most important information from each telescope to the Gamma Ray Burst Coordinate Network (GCN) on Earth as soon as it’s available. The GCN includes museums, scientists and ground-based telescopes around the world.
  
  
• Three data centres support Swift scientists: HEASARC (High Energy Astrophysics Science Archive Research Center) in the US; ISAC (Italian Swift Archive Centre) and the Swift Science Data Centre (UKSSDC) in the UK.

Technology

Swift uses three telescopes: BAT (Burst Alert Telescope), XAT (X-ray Telescope and UVOT (Ultraviolet/Optical Telescope).

BAT views around a sixth of the sky at any one time and is always looking for new bursts. Within two minutes of detecting a gamma ray burst by BAT, Swift automatically manoeuvres XAT and UVOT for precision measurements and long-term follow up.

XRT uses an X-ray CCD detector identical to those used on ESA’s XMM-Newton mission.

UVOT is a 30cm telescope and includes filters so that it can measure the spectrum of the afterglow. It is almost identical to the Optical Flying Monitor on XMM-Newton.

UK involvement

The University of Leicester hosts the UK Swift Science Data Centre, providing immediate access to Swift’s data 24 hours a day. The University supplied key systems designs for the XRT and built the low temperature CCD focal plane camera and the TAM (Telescope Alignment Monitor). It continues to support these in orbit as well as providing on-call scientists to analyse gamma ray bursts when they occur.

The Mullard Space Science Laboratory, University College London, helped build Swift’s UVOT. It also provides on going support for this instrument as well as on-call gamma ray burst scientists.

For more information, visit the UK’s Swift website or the NASA website.