Swift Fact Sheet

Swift is a first-of-its-kind multi-wavelength observatory dedicated to the study of gamma-ray burst (GRB) science. Its three instruments will work together to observe GRBs and afterglows in the gamma-ray, X-ray, optical, and ultraviolet wavebands. Swift, part of NASA’s medium explorer (MIDEX) program, is being developed by an international collaboration. It will be launched into a low-Earth orbit on a Delta 7320 rocket on October 7, 2004. During its nominal 2-year mission, Swift is expected to observe more than 200 bursts, which will represent the most comprehensive study of GRB afterglows to date.

The main mission objectives for Swift are to: Swift has a complement of three co-aligned instruments for studying gamma-ray bursts and their afterglow: the Burst Alert Telescope (BAT), the Xray Telescope (XRT), and the Ultraviolet/Optical Telescope (UVOT). The largest instrument on-board Swift is the BAT, which can view approximately a sixth of the entire sky at one time. It will detect approximately 100 or more gamma-ray bursts per year. Within seconds of detecting a burst, the spacecraft will "swiftly" and autonomously repoint itself to aim the XRT and UVOT at the burst to enable high-precision X-ray and optical positions and spectra to be determined. The positions will then be relayed to the ground for use by a network of observers at other telescopes. Swift will determine redshifts for most of the bursts that it detects (allowing scientists to know how far away they are and how absolutely bright they are), and will also provide detailed multi-wavelength light curves for the duration of the afterglow (allowing scientists to probe the physical environment in which the event took place). Key data taken by Swift will be relayed to the ground in near real-time, allowing the GRB Coordinate Network (GCN) to immediately distribute it to the world via the internet for follow-up observations and study. Swift will also use the BAT to perform an all-sky survey of low-energy gamma-rays that will be significantly more sensitive than any previous survey.

The Mission Operations Center (MOC) at Penn State University provides real-time command and control of the spacecraft and monitors the observatory, while also taking care of science and mission planning, Targets of Opportunity (ToO) handling, and data capture and accounting. The Italian Space Agency’s ground station at Malindi, Kenya provides the primary communications. Swift burst alerts and burst characteristics are relayed almost instantaneously through the NASA TDRSS space data link to the GCN for rapid distribution to the community.

Swift data will be made available to the world via three different data centers located in the United States (the High Energy Astrophysics Science Archive Research Center, HEASARC), the UK (the UK Swift Science Data Center, UKSSDC), and Italy (the Italian Swift Archive Center, ISAC).

The Swift Science Center (SSC) assists the science community in fully utilizing the Swift data. It is also responsible for coordinating the development of the data analysis tools for Swift data. The BAT instrument team and the Italian Swift Archive Center will develop data analysis tools for the BAT and XRT data respectively. The Swift Science Center is responsible for developing the UVOT tools.

Mission Details

Orbit: LEO 600 km circular
Orbital Life: 7 years
Inclination: 22 degrees
Launch Date: October 7, 2004
Prime Mission Duration: 2 years
Launcher: Delta II (7320)
Spacecraft Partner: Spectrum Astro
Peak Slew Rate: 50 degrees in < 75 seconds
Arrival: Within 3 arcmin of target
Operations and Pointing: Autonomous
Uplink/Downlink: Dual Path, 2 kbps GRB alert downlink and uplink real-time using TDRSS MA link, 2.25 Mbps data rat for store and dump using Malindi-ASI seven orbits per day

Burst Alert Telescope

Aperture: Coded Mask
Detecting Area: 5200 cm2
Detector: CdZnTe
Detector Operation: Photon Counting
Field of View: 2.0 sr (partially coded)
Detection Elements: 256 modules of 128 elements
Detector Size: 4mm x 4mm x 2mm
Telescope PSF: 17 arcminutes
Location Accuracy: 1-4 arcminutes
Energy Range: 15-150 keV
Burst Detection Rate: > 100 bursts/year

X-Ray Telescope

Telescope: Wolter I
Detector: XMM EPIC CCD
Effective Area: 135 cm2 at 1.5 keV
Detector Operation: Photon Counting, Integrrated Imaging, and Rapid Timing
Field of View: 23.6 x 23.6 arcminutes
Detection Element: 600 x 600 pixels
Pixel Scale: 2.36 arcsec/pixel
Telescope PSF: 18 arcsec HPD at 1.5 keV
Location Accuracy: 3-5 arcseconds
Energy Range: 0.2-10 keV
Sensitivity: 2 x 10-14 ergs cm-2 s-1 in 104 sec

Ultraviolet/Optical Telescope

Telescope: Modified Ritchey-Chrétien
Aperture: 30 cm diameter
F-number: 12.7
Detector: Intesified CCD
Detector Operation: Photon Counting
Field of View: 17 x 17 arcminutes
Detection Element: 2048 x 2048 pixels
Telescope PSF: 0.9 arcsec at 350 nm
Location Accuracy: 0.3 arcseconds
Wavelength Range: 170 nm - 650 nm
Colors: 6
Spectral Resolution (Grisms): λ/Δλ ~ 200 at 400 nm
Sensitivity: B = 24 in white light in 1000 sec
Pixel Scale: 0.48 srcseconds
Bright Limit: mv = 7 mag

Timeline of Burst Detection Events (Time (sec):Event)

0: GRB detection
20: Slew Begins/BAT approximate location distributed
~ 50: GRB acquired
70: XRT location distributed
240: UVOT finding chart distributed
300: XRT light curve distributed
1200: XRT spectrum distributed
~ 60,000: All automated observations complete (20,000 sec exposure)

Prime Institution: Goddard Space Flight Center
Lead University Partner: Penn State University
International Hardware Partners: Univeristy of Leicester, Mullard Space Science Laboratory, Osservatorio Astronomico di Brera, and ASI Science Data Center
Outreach: Sonoma State University and Penn State
Spacecraft Contractor: Spectrum Astro
Principal Investigator: Neil Gehrels, GSFC