Table 1. EUV Imaging Spectrometer Overview
| Telescope | |||
|---|---|---|---|
| Off-axis parabola | 15 cm diameter; half area:170-210Å, the other half:250-290Å |
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| Focal length | 1939mm | ||
| Off-axis distance | 70 mm | ||
| Plate scale at slit | 9.37 microns/arcsec | ||
| Multi-layer coating | Mo/Si pairs Peak efficiency at 19.5nm for one half area and 27.0nm for the other |
||
| Slits & Slots | 1", 2", 40", and 266" width at primary focus | ||
| Fine mirror scan range | ± 295" solar image motion in east-west direction for raster scan | ||
| Large FOV translation | ± 890" shift of FOV center in east-west direction | ||
| Spectrometer | |||
| Grating | Toroid surface, holographic and laminar ruling | ||
| 4200 grooves/mm | |||
| Wavelength range | Maximum coverage | 170-210Å, 250-290Å | |
| Useful coverage | 180-204Å, 250-290Å | ||
| Dispersion | 1.65 Å/mm or 0.0223 Å/CCD pixel | ||
| Pixel equivalent width | 34.3km/s @195Å, 26.1km/s @256Å, and 23.6km/s @284Å | ||
| Plate scale at CCD | 1.0" / CCD pixel | ||
| CCD camera | CCD | Device | Marconi 42-20, MPP |
| Format (Spatial × Spectral) | 1024 × 2048 pixel for each CCD | ||
| Pixel size | 13.5 micron | ||
| Readout electronics | Window size | 512 × 2048 max for each CCD from 1024 × 2048 area | |
| ICU in spacecraft bus | Number of spectral windows | 25 maximum | |
* FOV of 1024" is guaranteed in north-south direction on the CCD. Height of 512" out of 1024" can be read in a single exposure.
Table 2. EIS Instrumental Performance
| Instrument Performance | ||
|---|---|---|
| Effective Area | 0.23 cm2 peak @ 195Å for 170-210Å band 0.06 cm2 peak @ 270Å for 250-290Å band |
|
| Expected line intensity from 1" × 1" area |
Quiet Sun | 8 photons/s for Fe XII 195Å 2 ph/s for He II 256Å |
| Active Region | 2 × 102 ph/s for Fe XII 195Å 1 × 101 ph/s for He II 256Å 1 × 102 ph/s for Fe XV 284Å |
|
| M2-class Flare | 4 × 104 ph/s for Fe XXIV 192Å 3 × 103 ph/s for Fe XXIV 255Å 4 × 103 ph/s for He II 256Å 1 × 103 ph/s for Fe XV 284Å |
|
| Accuracy of measurement | Doppler velocity | v = 2 km/s for 2 × 102 photons (Fe XV 284Å) v = 3 km/s for 2 × 103photons (Fe XXIV 255Å) |
| Line width | dw = 4 km/s for 2 × 102 photons (Fe XV 284Å) dw = 9 km/s for 2 × 103 photons (Fe XXIV 255Å) |
|
| Data compression in MDP | Bit compression: 16-to-12 bit or 14-to-12 bit compression | |
| Image compression: DPCM (loss less) or 12bit-JPEG | ||
| Data rate | 1/8 of total telemetry (40kbps) after compression | |
| Control of EIS observation | Observing sequence in EIS ICU | |