COS Throughput

Detailed measurements of the throughputs of the COS optical systems have not yet been made during ground testing of the instrumentation. Component testing indicates that COS should be considerably more sensitive than STIS and earlier generation HST instruments at comparable spectral resolutions. At FUV wavelengths, the peak effective area is expected to reach ~2700 cm2 near 1300 Å with the G130M grating. At NUV wavelengths, the peak effective area is expected to reach ~1000 cm2 near 2350 Å with the G225M grating.

For further information, see section 13.4 of the COS Instrument Handbook.