5.10. Cosmic Origins Spectrograph (COS)
This new spectrograph will be installed in the bay currently occupied by COSTAR during the fourth servicing mission in 2002. COS is a large format slitless UV spectrometer with three gratings:
| Wavelength Coverage |   /
| |
| High Dispersion Channel 1 (HDC1) | 1150Å - 1450Å | 20000 - 24000 |
| High Dispersion Channel 2 (HDC2) | 1405Å - 1775Å | 20000 - 24000 |
| High Sensitivity Channel (HSC) | 1230Å - 2000Å | 2500 - 3000 |
The detector is a windowless microchannel-plate array, with an opaque CsI photocathode, and a double delay-lien readout. It is optimized for UV and far UV spectroscopy.
COS most frequent use will be in time-tag photon counting mode. For brighter target an image accumulation mode can be used too.