SIMBAD references

The quality of astronomical spectroscopic data now available is so high that interpretation and analysis are often limited by the uncertainties of the laboratory data base. In particular, the limit with which space-time variations in the fine structure constant α can be constrained using quasar spectra depends on the availability of more accurate laboratory rest wavelengths. We recently measured some transitions in magnesium by high-resolution Fourier transform spectroscopy for this purpose, and we now report measurements on some ultraviolet resonance lines of Znii (2062 and 2026Å), Crii (2066, 2062 and 2056Å) and Niii (1751, 1741, 1709 and 1703Å). Apart from the last line, which is very weak, the uncertainty of these measurements is 0.002cm^–1 (0.08må) for the lines around 2000Å and 0.004cm^–1 (0.12må) for the lines around 1700Å.