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Swift Spacecraft and Instruments

Swift Spacecraft and Instruments. Spacecraft Design. Star Trackers. Gyros. 1 of 6 Reaction wheels. Swift Overview Catching Gamma Ray Bursts on the Fly. Capabilities ~ 1000 GRBs studied over a three-year period 0.3–2.5 arc-second positions for each GRB

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Swift Spacecraft and Instruments

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  1. Swift Spacecraft and Instruments Swift

  2. Spacecraft Design Star Trackers Gyros 1 of 6 Reaction wheels Swift

  3. Swift OverviewCatching Gamma Ray Bursts on the Fly • Capabilities • ~ 1000 GRBs studied over a three-year period • 0.3–2.5 arc-second positions for each GRB • Multiwavelength observatory (gamma, X-ray, UV, and Optical) to monitor afterglows • 20–70 s reaction time • Five times more sensitive than BATSE • Spectroscopy from 0.2 to 150 keV • Six colors covering 170–650 nm • UV and optical spectroscopy with R ~ 300–600 for Mb < 17 • Capability to directly measure redshift • Results publicly distributed within seconds Swift

  4. Swift Mission Features • Multi-wavelength observatory • Burst Alert Telescope (BAT): 10-150 keV • detect ~ 300 gamma ray bursts per year • onboard computation of positions • arc-minute positional accuracy • Dedicated telescopes for X-rays, UV, and optical afterglow follow up: • 0.3-10 keV X-ray Telescope (XRT) • 170-650 nm UV/Optical Telescope (UVOT) • 0.3-2.5 arc-second locations • existing hardware from JET-X and XMM • determine redshifts from X-ray absorption, lines, and Lyman-a cutoff • Rapid response satellite • 20 - 70 sec to slew within FOV of BAT • autonomous operations • factor of > 100 improved response time • continue monitoring of fading afterglow for days to weeks after the event Swift

  5. Swift Instrumentation I. Burst Alert Telescope (BAT) • Real time gamma ray burst positions • half coded 2 steradian FOV • 5200 cm2 CdZnTe pixel array • 10–150 keV band • based on INTEGRAL Imager design • 5 times more sensitive than BATSE • ~ 1 burst per day detected • (depends of logN-logS extrapolation) • angular resolution of 22 arc-minute giving positions of 1–4 arc-minute • onboard processing to provide prompt arc-minute position to satellite ACS and to the ground 4 mm BAT CdZnTe 8 x 16 element detector module Swift

  6. Swift Instrumentation II. X-ray Telescope (XRT) • Flight spare JET-X module • 15 arc-second half energy width • sharp core will yield arc-second locations • 3.5 m focal length • Total effective area • 110 cm2 at 1.5 keV • 65 cm2 at 6 keV XRT Mirror Module • CCD array covers 0.2-10 keV band • use spare XMM chip • 24 x 24 arc-minute field of view • Cooled to -80 degrees C Swift

  7. Swift Instrumentation III. UV-Optical Telescope (UVOT) • Based on XMM OM to minimize cost and risk • Covers 170 nm to 650 nm • 30 cm Ritchey-Chretien telescope • 24 mag in 1000 s with 17 arc-minute FOV • Detector is image intensified CCD array • Unique coverage 20-70 s after • burst trigger • Positions to 0.3 arc-seconds using onboard image registration • UVOT will be simple reproduction of • XMM OM XMM OM Filter Wheel Swift

  8. UVOT Performance Measured UVOT Response Percent Transmittance Wavelength • Positions to 0.3 arc-seconds using onboard image registrations • Filters give spectral/color information and allow redshift determination from Lyman edge detection UVOT Sensitivity For V = 20 B star in 1000 s get: UVW2 680 cts UVM2 800 cts UVW1 1000 cts Sensitivity to Ly-a cutoff: UVM1 - UVM2 z ~ 1.5 UVM1 - UVM1 z ~ 2 U - UVW1 z ~ 2.7 B - U z ~ 3.5 • UV and optical grisms with Dl of 0.5 nm and 1.0 nm, respectively, for Mb < 17 • IUE type resolution Swift

  9. Multiwavelength Cascade of Images Gamma Ray (arc-minute) X-ray (2.5 arc-second) HST, Keck, etc. UVOT (0.3 arc-second) Swift

  10. Observing Strategy • Allow both onboard and external triggers (from, e.g., INTEGRAL) • Slew to new burst as soon as possible • Follow all afterglows for as long as they are visible • typically Swift will be monitoring a few afterglows Swift

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