Spectrographic Imager (SI)
SI is designed to image the whole Earth proton aurora at greater than 4 Re.
Observes at the Doppler shifted Lyman H-alpha line at 121.82 nm in the ultraviolet part of the optical spectrum and rejects the non-Doppler shifted Lyman H-alpha from the geocorona at 121.567 nm.
The SI Characteristics are summarized below:
- Doppler shifted spectral line at 121.82 nm
- Field of view 15x15 degrees
- Resolution elements of less than 0.15 degrees
- Temporal resolution 120 seconds
- 128 x 128 pixels (less than 100 km spatial resolution at apogee)
- Goal sensitivity 100 R in the presence of 10 kR at 121.6 nm