The LWS processing corrects the data for the effective aperture of the
instrument, assuming that the source that is observed is a point
source in the center of the LWS aperture. For an extended source
a correction has to be applied to the calculated fluxes, because
for an extended source (that is bigger than the LWS aperture)
the diffraction of the telescope shall not be wavelength dependent.
For a point source the instrument is diffraction limited at
about 110 
m, so for longer wavelengths the effective aperture
of the instrument will be smaller (part of the flux will be
defracted out of the aperture). For a source that is in between
these to cases, the procedure is more complicated and would involve
a deconvolution with the instrument beam pattern. At this moment
the procedure to do this is not yet known. In Table 7.2
the correction factor for the center wavelengths of the ten
detectors is given for point and extended sources.
Table 7.2: The
correction factors for the effective aperture of the instrument. Please
note that these are very rough estimates.
