View
231
Download
0
Category
Tags:
Preview:
Citation preview
Swift1
Swift Spacecraft and Instruments
Swift2
Spacecraft Design
1 of 6 Reaction wheels
Gyros
Star Trackers
Swift3
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
Swift4
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- 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
Swift5
Swift Instrumentation
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
I. Burst Alert Telescope (BAT)
BAT CdZnTe 8 x 16 element detector module
4 mm
Swift6
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
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
XRT Mirror Module
Swift7
Swift Instrumentation
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
III. UV-Optical Telescope (UVOT)
Filter Wheel
XMM OM
Swift8
UVOT Performance
Wavelength
Pe
rce
nt
Tra
nsm
itta
nce
Measured UVOT Response
UV and optical grisms with of 0.5 nm and 1.0 nm, respectively, for Mb < 17
• IUE type resolution
UVOT Sensitivity
For V = 20 B star in 1000 s get:
UVW2 680 ctsUVM2 800 ctsUVW1 1000 cts
Sensitivity to Ly- cutoff:
UVM1 - UVM2 z ~ 1.5UVM1 - UVM1 z ~ 2U - UVW1z ~ 2.7B - U z ~ 3.5
Positions to 0.3 arc-seconds using onboard image registrations Filters give spectral/color information and allow redshift determination from Lyman edge detection
Swift9
Multiwavelength Cascade of Images
Gamma Ray (arc-minute)
X-ray (2.5 arc-second)
UVOT (0.3 arc-second)
HST, Keck, etc.
Swift10
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
Time S/C Event Time POC Event
0 s GRB
10 s Slew Begins 12 s BAT location distributed
~ 50 s GRB acquired
55 s XRT image 62 s XRT location, BATlightcurves distributed
150 s UVOT findingchart
200 s Optical finding chartdistributed
1200 s XRT spectrum 1210 s XRT spectra distributed
7200 s UVOT filterscomplete
~ 104 s Ground stationpass
All burst data, Newobserving programuploaded
Recommended