nasa facts swift catching gamma ray bursts on the fly

8/7/2019 NASA Facts Swift Catching Gamma Ray Bursts on the Fly

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Catching Gamma-Ray Bursts on the Fly

Gamma-ray bursts are the most powerful ex-plosions in the Universe other than the BigBang. They occur several timesper day, yet scientists still haveonly patchy details about whatcauses them. Each burst likelysignals the birth of a new black

hole -- perhaps either througha massive star explosion or afantastic merger between neu-tron stars or black holes.

Now theres a satellite designedto capture and analyze thesebursts, some of which last onlyfor a few milliseconds. NASAsSwift mission is a three-tele-scope space observatory. One

of the telescopes will detect gamma-ray bursts; the other two will scru-tinize the afterglow of the burst.Swift is a unique multi-wavelengthmission. Its three telescopes spanthe gamma-ray, X-ray, ultravioletand optical light bands, a swath ofthe spectrum over a million timeswider than what the Hubble SpaceTelescope detects.

National Aeronautics and

Space Administration

Goddard Space Flight Center

Greenbelt, Maryland 20771

(301) 286-0039

FS-2004-8-069-GSFC

Catching Gamma Ray Bursts on the FlyDuty Calls, Swift Responds:

Swift is the first mission to focus on study-ing the burst afterglow, a phenomenon

discovered in 1997. Within sec-onds after detecting a gamma-rayburst, Swift will relay an accurateburst position to scores of orbit-ing and ground-based observato-

ries so that they can observe theafterglow before it fades. Themessage goes out literally via e-mail and cell phones to scientistsand amateur astronomers. Swiftis also in contact with ground-based robotic telescopes waitingfor Swifts commands.

Swift itself will focus its X-ray andUV/optical telescopes on the af-

terglow within about a minute. Thisenables Swift to determine distancesfor most of the bursts that it detectsand provide detailed multi-wave-length light curves for the durationof the afterglow. Time is of the es-sence. Many bursts last about 10 sec-onds; the longest last about a minute.Once they are gone, the afterglowsare hard to find. And the afterglows,like a crime scene, contain all the evi-Hubble Image of GRB

990123

Artists Illustration of Swift

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dence about the burst. Scientists have yet tofind an afterglow of a short burst (less than 2seconds). Maybe there is no afterglow; may-be were just not fast enough. Swift will leadto the detection of short-burst afterglows, ifthey exist, and determine whether they areintrinsically different from longer bursts.

Importance of Afterglow

Measurements:

Distances determined from gamma-ray burstafterglows have enabled scientists to under-stand that these bursts originate very far awayfrom us. In fact, the bursts may be locatedin the most distant galaxies we can observe.The power they produce each second is truly

extreme, about 1050

1051

ergs, comparedto the Suns 4 x1033 ergs. Each gamma-rayburst is like a billion billion suns.

Many models have been proposed to explaingamma-ray bursts and their afterglows. What remains bewildering is the sheerdiversity of the bursts. Some last for only afew milliseconds. Others last upwards of aminute. Some produce afterglows. Some aredominated by X-ray photons (light particles).Some show traces of iron atoms, a sign of

a star explosion.Scientists indeed joke that if youveseen one gamma-ray burst, youveseen one gamma-ray burst.

The large sample ofbursts that Swift will

collect will enablescientists to test the-ories and, for thefirst time, performmulti-wavelengthobservations of the very short bursts,which have eludedground-based ob-servers. We mayfind that differentkinds of bursts arecaused by differentorigins, such as merg-ers of orbiting neutrons stars or gigantic stel-lar explosions known as hypernovae.

Astronomy and Physics Lessons:

Understanding gamma-ray bursts will reveal

new insights about the Universe. Most burstsoriginate at cosmological distances, which means they ignited billionsof light years away when the Uni-verse was much younger. They actlike beacons shining through every-thing along their paths, includingthe gas between and within galaxiesalong the line of sight.

Some bursts may be from the firstgeneration of stars. If so, we can be-gin to map out early star formation,which has not yet been done. Also,if gamma-ray bursts truly signal thebirth of a black hole, scientists canat last measure the black hole for-mation rate in the Universe.

Gamma-ray bursts are laboratoriesfor extreme physics. The explo-sions create blast waves that accel-erate matter to nearly the speed of

light. Such conditions cannot bereproduced on Earth, but scientistscan watch and learn from afar.

Swift Instrumentation:

The main instrument onboard Swiftis the Burst Alert Telescope (BAT).The BAT has a wide field of viewand will detect and locate abouttwo gamma ray bursts per week,

Hypernova Illustration

Neutron Star MergerIllustration

Swift Electronics Testing


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Swift Mission

GRB Position Accuracy 0.3-5 arcsec

Repointing Time 20-75 seconds

Lifetime 2 years minimum

Height 5.64 m

Mass 1470 kg

Power 1040 Watts

Delta 7320Launch vehicle

Orbital inclination 21 degrees

Lead Institutions Involved

NASA Goddard Space Flight Center, USA

Penn State University, USA

General Dynamics C4 Systems, USASpectrum Astro Space Systems

University of Leicester, UK

Mullard Space Science Lab, UK

Brera Observatory (OAB), Italy

Los Alamos National Laboratory, USA

- BAT instrument, Project Management

- XRT, UVOT, Operations

- Spacecraft Vendor

- X-ray Telescope and Detectors

- UVOT Assembly

- X-ray mirrors for the XRT

- BAT Instrument Flight Software

Area of Support

Italian Space Agency, Italy

-Ground Station Support

Sonoma State University, USA-Education and Public Outreach

Follow Up Team Observatories and Facilities:

AEOS Telescope (Hawaii)

ARAGO Telescope (Antarctica)

ARC Telescope (New Mexico)

Brera Observatory (Italy)

ESO (La Silla, Paranal, VLT)

ESAs INTEGRAL mission

Fast Alert MachinE (Italy)

Faulkes Telescope Project (Hawaii and Australia)

Galileo National Telescope (La Palma)

Hobby-Eberly Telescope (Texas)

Isaac Newton Telescopes (La Palma)

KAIT (California)W. M. Keck Observatory (Hawaii)

Large Binocular Telescope (Arizona)

LIGO (Louisiana and Washington)

Liverpool Telescope (La Palma)

McDonald Observatory (Texas)

Milagro Gamma-ray Observatory (New Mexico)

NASA (IRTF, Hubble & Spitzer Space Telescopes)

NOAO (CTIO, KPNO)

Nordic Optic Telescope (La Palma)

Okayama Observatory (Japan)

Rapid Eye Mount Telescope (Chile)

ROTSE-III (New Mexico)

SARA Observatory (Arizona)

South African Large Telescope

Super-LOTIS (Arizona)

TAOS Telescope (Taiwan)

TAROT Telescope (France)

Tenerife Observatory

U.S. Naval Observatory (Arizona)

VERITAS Observatory (Arizona)

WASP Telescope (La Palma)

WIYN Observatory (Arizona)

Wyoming Infrared Observatory

nasa facts swift catching gamma ray bursts on the fly

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