SIMBAD references

Spectra observed with the Ultraviolet and Visual Echelle Spectrograph on the European Southern Observatory's VLT exhibit long-range wavelength distortions. These distortions impose a systematic error on high-precision measurements of the fine-structure constant, α, derived from intervening quasar absorption systems. If the distortion is modelled using a model that is too simplistic, the resulting bias in Δα/α away from the true value can be larger than the statistical uncertainty on the α measurement. If the effect is ignored altogether, the same is true. If the effect is modelled properly, accounting for the way in which final spectra are generally formed from the co-addition of exposures made at several different instrumental settings, the effect can be accurately removed and the correct Δα/α recovered.