Laboratory atomic transition data for precise optical quasar absorption
  spectroscopy
  Quasar spectra reveal a rich array of important astrophysical information
about galaxies which intersect the quasar line of sight. They also enable tests
of the variability of fundamental constants over cosmological time and
distance-scales. Key to these endeavours are the laboratory frequencies,
isotopic and hyperfine structures of various metal-ion transitions. Here we
review and synthesize the existing information about these quantities for 43
transitions which are important for measuring possible changes in the
fine-structure constant, alpha, using optical quasar spectra, i.e. those of Na,
Mg, Al, Si, Ca, Cr, Mn, Fe, Ni and Zn. We also summarize the information
currently missing that precludes more transitions being used. We present an
up-to-date set of coefficients, q, which define the sensitivity of these
transitions to variations in alpha. New calculations of isotopic structures and
q coefficients are performed for SiII and TiII, including SiII 1808 and TiII
1910.6/1910.9 for the first time. Finally, simulated absorption-line spectra
are used to illustrate the systematic errors expected if the isotopic/hyperfine
structures are omitted from profile fitting analyses.
  To ensure transparency, repeatability and currency of the data and
calculations, we supply a comprehensive database as Supporting Information.
This will be updated as new measurements and calculations are performed.
