Sensitivity

The continuum and line sensitivities of the SPI instrument are given in Figure and Figure , respectively. The continuum sensitivities are for , and are calculated using the narrow line sensitivity divided by , where R is the instrument resolution for lines. The line sensitivities are fluxes in photons cm  s , the continuum sensitivities are fluxes in photons cm  s keV . The line sensitivities are for narrow lines. The 511 keV sensitivity is worse than the surrounding continuum due to the strong 511 keV background line originating in the instrument.

Figure: The continuum sensitivity of the SPI instrument for a 3 sigma detection in 10 seconds, on axis. The fluxes are for The dashed lines indicate extrapolations from the X-rays using a powerlaw with photon index -2 for 1, 10 and 100 mCrab.

Figure: The narrow line sensitivity of the SPI instrument for a 3 sigma detection in 10  s. Note that the 511 keV line is not shown in this figure.