Expected Accuracy

The final calibration of the SWS results will depend on how well the memory effects of the detectors can be controlled and modelled under in-orbit conditions. The following goals have been set for the calibration programme:

• Photometric absolute calibration to 30% and relative calibration to 10% for both grating and F-P observations. Differences between the flux calibration for point sources and extended sources will be modelled on the basis of the known aperture sizes and diffraction patterns.
• Wavelength calibration to 1/5 of a resolution element for the grating and to 1/3 of a resolution element for the F-P.
• Calibration of the FWHM of the instrumental profile to 10% for both the grating and F-P, and characterization of wings of the instrumental profile. The grating instrumental profile has to be characterized both for point sources and extended sources. The accuracy with which instrumental profiles for both the grating and the F-P can be obtained is limited by various factors (memory effects, mechanical stability, pointing stability, availability of narrow lines). It is hence not expected that the instrumental profiles will be suitable for deconvolution.