1. Optical Telescope Assembly (OTA) specifications
Optics type
Aplanatic Gregorian with heat dump mirror
Primary mirror
50cm diameter aperture, light-weighted ULE
Primary-secondary mirror length
1.5 m
Central obscuration ratio
0.344 in radius
Effective F ratio
9.055 at secondary focus
Collimator Lens (CLU)
3cm diameter exit pupil, collimated in air
Polarization Modulator (PMU)
Continuous rotation, 1.6 sec/rotation
retardation N ±0.35 waves at 630/517/525 nm
retardation N ±0.35 waves at 630/517/525 nm
2. Image stabilization system
| Correlation tracker | |
|---|---|
| CCD | 50"×ばつ50" pixel (0.22 arcsec / pixel) |
| Frame rate | 580 Hz |
| Spectral range | 629 - 634nm |
| Displacement Range | ±5 pixel |
| Error signal accuracy | 0.01" |
| Tip-tilt mirror and its control | |
| Signal used for closed loop control | Redidual signal from correlation tracker |
| Actuator | 3 Piezo actuators |
| Tilt range | 10.5" in radios on the sky |
| Control crossover frequency | 14 Hz (nominal gain) |
| Stability | < 0.02" (in laboratory environment) |
3. Broadband Filter Imager (BFI)
| Field of view | 218" ×ばつ 109" (full FOV) | ||
|---|---|---|---|
| CCD | 4k ×ばつ 2k pixel (full FOV), shared with the NFI | ||
| Spatial Sampling | 0.0541 arcsec/pixel (full resolution) | ||
| Spectral coverage | |||
| Center (nm) | Band width (nm) | Line of interest | Purpose |
| 388.35 | 0.7 | CN I | Magnetic network imaging |
| 396.85 | 0.3 | Ca II H | Chromospheric heating |
| 430.50 | 0.8 | CH I | Magnetic elements |
| 450.45 | 0.4 | Blue continuum | Temperature |
| 555.05 | 0.4 | Green continuum | Temperature |
| 668.40 | 0.4 | Red continuum | Temperature |
| Exposure time | 0.03 - 0.8 sec (typical) | ||
4. Narrowband Filter Imager (NFI)
| Field of view | 328"×ばつ164" (unvignetted 264"×ばつ164") | |||
|---|---|---|---|---|
| CCD | 4k×ばつ2k pixel (full FOV), shared with BFI | |||
| Spatial sampling | 0.08 arcsec/pixel (full resolution) | |||
| Spectral resolution | 0.009nm (90mÅ) at 630nm | |||
| Spectral windows (nm) and lines of interest | ||||
| Center | Tunable range | Lines | geff | Purpose |
| 517.2 | 0.6 | Mg I b 517.27 | 1.75 | Chromospheric Dopplergrams and magnetgrams |
| 525.0 | 0.6 | Fe 524.71 | 2.00 | Photospheric magnetograms |
| Fe I 525.02 | 3.00 | |||
| Fe I 525.06 | 1.50 | |||
| 557.6 | 0.6 | Fe I 557.61 | 0.00 | Photospheric Dopplergrams |
| 589.6 | 0.6 | Na I D 589.6 | - | Very weak fields (scattering polarization) Chromospheric fields |
| 630.0 | 0.6 | Fe I 630.15 | 1.67 | Photospheric magnetograms |
| Fe I 630.25 | 2.50 | |||
| Ti I 630.38 | 0.92 | Umbral magnetograms | ||
| 656.3 | 0.6 | H I 656.28 | - | Chromosphreic structure |
| Exposure time | 0.1 - 1.6 sec (typical) | |||
5. Spectro-polarimeter (SP)
Field of view along slit
164" (north-south direction)
Spatial scan range
±164"
Slit width
0.16"
Spectral coverage
630.08nm - 630.32nm
Spectral resolution / sampling
30mÅ / 21.5mÅ
Measurement of polarization
Stokes I,Q,U,V simultaneously with dual beams (orthogonal linear components)
Polarization signal to noise
103 (with normal mapping)
6. Observation controls and data handling
Effective process speed of MDP
832k pixels/sec (maximum for FPP data)
Pixel depth compression by MDP
16 bit to 12 bit, 8 lookup tables
Image compression ratio
(depends on images) 12bit DPCM lossless 6-8 bits/pixel
(depends on images) 12bit DPCM lossless 6-8 bits/pixel
12bit JPEG(DCT) lossy
<3bits /pixel for FG
1.5 bits/pixel for SP
1.5 bits/pixel for SP
Allocated telemetry rate for SOT
1.3Mbps (nominal)
1.8Mbps (SOT dominant)
1.8Mbps (SOT dominant)
Average data rate
300kbps (15 downlink contacts / day)