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3.3.1 Blackbody spectrum example

The expected count rate from a source with a blackbody spectrum
(perhaps a neutron star) needs to be estimated. The source has L
_{x} = 10^{33} ergs s^{-1} in the ROSAT energy band (0.1 to 2.4 keV), and
is at a distance of 2 kpc with N
_{H} = 1 `x` 10^{21} cm^{-2}(log(N
_{H}) = 21). The assumed temperature is equivalent to 0.1
keV. The unabsorbed flux for this source is
*F*_{S, 0} = 2.09 `x` 10^{-12} ergs cm^{-2} s^{-1}. From Table 11 or Figure 33, the
appropriate ECF is
5.63 `x` 10^{9}, and the expected count rate
is 0.012 ct s^{-1}. We estimate that a detection of this source at
the 5
level will require an observation time of about 4,000
seconds.

*rsdc@cfa.harvard.edu *

1999-05-25