•Detector
−Photocathode
•Material KBr
•Quantum efficiencies
83%
@ 950Å
•
77%
@ 1000Å
•
74% @ 1150Å
−Permanent Magnet Focus Assembly
•Field strength 132 gauss
•Angle between B and E
20°
•Field uniformity 2 gauss
−Electrostatic assembly
•Operating voltage 18.5 kV
−CCD (RCA type SID-502)
•Pixel format 320 ✕ 256
•Active area 9.6 mm ✕ 7.7mm
•Charge well
dimensions 30μm ✕ 30μm
•Charge well
capacity 8.5 ✕ 105 e-
•Amplifier output 1.5μV/e-
•Secondary electron
yield for 2500 e- for
18.5 kV
•Lateral spread of
secondary 8 – 12 μm electrons (distance between 1/e points)
−Output signal characteristics
•Frame rate 15 Hz
•Pixel dwell time 0.60 μs
•Frame transfer time: A→B register 1.78ms
•rms noise in each pixel 75e-
•Dark current: 3000 e- @20° C
• ( varies by ~30% over the image format)
•Image Layout
–Angles in the sky
•CCD field of view 18’20” ✕ 14’40”
•Image scale 115” mm-1
•CCD pixel 3.45”
–Lowest echelle order 197
•Order separation 178 μm
•Central λ 1150 Å
•Free spectral range
35.5
mm = 5.5 Å
–Highest useful echelle order 238
•Order separation 122 μm
•Central λ
950
Å
•Free spectral range 29.0 mm = 3.7 Å
–Echelle angle settings
•Number
4
•Overlap of adjacent settings 0.42 mm
–Sample characteristics
•Mean dispersion: (λ/1000Å)✕ 0.139Å mm-1
•Sample size along orders 30 μm
•Sample size ┴ to orders 30 μm
•Instrumental profile
60
– 90 μm FWHM (Δλ ≥ λ/2.3 ✕ 105)
–Broad band star images for guidance corrections (sounding
rocket flights only)
•Location 0.78 mm (90”) from
short λ edge
•Brightness ~ 50 events per 1/15
s frame
• λ range 1250 – 1500 Å
•