In-orbit the LWS was generally a well behaved and linear instrument, therefore the only persistent problem many users will find with their data is the presence of glitches (Section 6.1) and often a small difference between the two scan directions due to transients (Section 6.9). Spurious spectral features are fairly rare but those known are covered in Sections 6.7 to 6.11.
The 10 sub-spectra may not completely match photometrically (Section 6.5) for various reasons, such as statistical errors in the dark current (Section 6.4) and responsivity determination during processing (Section 4.4.1). The instrument also becomes non-linear when exposed to high fluxes (Sections 5.7 and 6.10).
For observers with data from extended sources, the LWS optics caused fringing and fracturing in the beam and these effects are described in Sections 6.2 and 6.3. As the LWS photometric calibration is based on a point source, these effects combined with diffraction will mean that the matching between sub-spectra will be worse for extended sources than point sources.
There are a further two caveats specific to the FPs, an unexplained systematic error in the wavelength calibration which nevertheless remains within the accuracy specifications (Section 6.12) and a problem, mainly concerning L03 observations, where the grating element is not placed accurately enough for the FP scan to be in the centre of the grating profile (Section 6.13).
m SW2 Feature in the Fabry-Pérot Spectra