1 Introduction

The purpose of this document is to :

• Shortly describe how new Relative Spectral Response Functions (RSRFs) are determined
• Show the differences we see between RSRFs derived from pre-launch lab data and in-orbit data in order to give an idea about the uncertainties in the present RSRF calibration
• Indicate how some features or uncertainties in the RSRF might introduce false features in the AAR and give an overview of the 'dangerous spots' in each AOT band where such problematic features are present.

The purpose of this document is not to :

• Create panic; however it is advisible to carefully read through this document and review the interpretation of your SWS data for the A&A issue. If you have any doubts, ask the opinion of an SWS expert.
• Give a complete overview of our present understanding of all RSRF related issues. This will be done in the SIDT PV wrap-up report.

The curves of the RSRFs as measured in the laboratory are not new: they can be found in the SWS observer's manual as well. They are only shown again to compare against what we see in orbit.