Institut d'Astrophysique Spatiale, Université Paris-Sud, Bât. 121, 91405 Orsay Cedex, France
Up to now, the photometric accuracy of the LW channel of ISOCAM is not better
than
10
.
This is mainly due to limitations of the models commonly used to process the
data
(especially the IAS model, Abergel et al. 1998).
We present a new approach based on the model of Fouks and Schubert (1995) which
was developed
for the PHT-S detectors of ISOPHOT. Applied to ISOCAM-LW for uniform
illumination, this
model describes upward and downward steps with an error lower than 1.
For
most of the
observations, the flux steps are limited, and the Fouks-Schubert equation can
be developed
in a third-order polynomial. Therefore, the model is analytically inversible.
The computing
times are reduced by a factor more than 10 compared to previous methods.
For extended emission, first results show that the accuracy of the correction
is
1.
It gives remarkable results for (1) changes of filters on
uniform
emission, (2) CVF observations, since the shape of the continuum is corrected
over
the full spectral range of observation.