SIMBAD references

We use very high quality VLT-UVES quasar spectra obtained in the course of the ESO Large Programme ``Cosmic evolution of the Intergalactic Medium", to show that the ratio of the C IV doublet rest-wavelengths published in the literature and widely used is not consistent with high-redshift observations. From the analysis of 106 C IV systems we obtain: λ₂/λ₁=1.00166228±0.13x10^–6. A similar analysis on 28 Si IV systems shows that the observed ratio is consistent with the well known Si IVλλ1393,1402 wavelengths. Using Si IV lines to calibrate the C IV lines in 11 systems, we find λ_1,2=1548.2049 and 1550.7785±0.0012Å which is consistent with the Griesmann & Kling (2000ApJ...536L.113G) laboratory wavelengths. The precision on the doublet ratio is better because of the large number of C IV systems available for the measurement. This shows that it is possible to perform atomic physics measurements using high redshift astrophysical data.