COS Sensitivity Summary

The predicted sensitivities for the various FUV and NUV spectroscopic modes are shown in Fig. 3. As a figure of merit, we expect to obtain S/N $\approx 10$ per resolution element in the R $\geq$ 20,000 channels for sources with fluxes of $1-2 \times 10^{-15}$ ergs cm^-2 s^-1 Å^-1 in 10,000 sec per exposure across most of the 1150 - 3200 Å wavelength range covered by COS. This Web page will be updated periodically as the COS instrument capabilities and performance are developed.

  

Figure 3: Sensitivity predictions for point sources observed with the various COS FUV and NUV grating modes. The sensitivities shown include the throughput of the HST OTA and a COS `slit' transmission of ~97% through the standard 2.5'' aperture. (Use of the Bright Object Aperture will attenuate the COS sensitivity by a factor of 100.)