This section describes the different noise components of the SW
and LW channels for the different observing modes. They are given
for a stable signal, far from any transient (cf. Sections
and ).
Units for all physical quantities, namely rms fluctuations and
signal strengths, are expressed in ADUs in the formulae to follow.
Since the numerical constants in these formulae apply to a gain
factor of 
2, rms values and signal strengths should be
scaled according to the actual value of the gain.
Glitches and straylight may reduce the sensitivity in some circumstances.