Max-Planck-Institut für extraterrestrische Physik
Background
Deutsche Version MPE HEG X-Ray Astronomy Wave ROSAT
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Background
In-orbit experience has shown that the background in the
short-wavelength filter (``S1'') is dominated by cosmic rays
and by a spacecraft related spacecraft glow phenomenon.
In the shorter wavelength filters additional components are
present due to resonantly scattered photons from the strong
emission lines in the solar spectrum
(most notably the 
line of He II).
Table 6.4
gives the approximate ranges and orbit-averaged count rates
for each of the background components,
Tab. 6.5
gives the typical overall background rate in each filter.
It should be stressed however that all of the components
(with the exception of the MCP intrinsic noise) are time
variable with periods ranging from minutes to months,
dependant on the component concerned.
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