that the flux-calibration is robust, and verify that quasar variability, on average, is a minor effect.

To test if a systematic offset in the wavelength-solution exists and to determine velocity-dispersions, we measure central wavelengths and full-width-half-maximum (FWHM) of sky lines proximate to object emission lines in the 2D spectra. Gaussian- and Voigt profile-fitting ensured accurate central wavelengths, but systematically underestimated the FWHM measurements. The central wavelengths are measured against the Ultra-Violet and Echelle Spectrograph (UVES) telluric line catalogue [@Hanuschik2003], yielding an effective offset in the wavelength-solution reported in Table \[tab:obslog\]. With non-parametric FWHM measurements we confirm the nominal instrumental resolutions [^3] renormalised to a 1.31 arcsec slit-width, giving effective resolutions $\mathcal{R}_\text{600RI}=763$ ($\sim 393~\text{km s}^{-1}$), and $\mathcal{R}_\text{600z}=1061$ ($\sim 283~\text{km s}^{-1}$).

Archival data
-------------

In addition to the FORS2 observations described in Sec. \[sec:FORS2data\], we have compiled the archival data we require in each of the targeted fields. This includes the Galactic extinction towards the lines of sight, the absorber characteristics ($z_{\mathrm{abs}}$, , $[\mathrm{M/H}]_{\mathrm{abs}}$) and the candidate host characteristics ($z_{\mathrm{phot}}$ and photometry).

The photometry is predominantly taken from [@Rao2011], with optical images obtained at the Kitt Peak National Observatory (KPNO) with standard SDSS $u'$, $g'$, $r'$, $i'$ filters, and Near-IR (NIR) images 