& \[<span style="font-variant:small-caps;">O ii</span>\] & 3727,3729 & $5.5 \pm 0.7$ & $7.0 \pm 0.7$\

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Q2335+1501 & 3.8 & 27.0 & $0.67989 \pm 0.00002$ & \[<span style="font-variant:small-caps;">O ii</span>\] & 3727,3729 & $6.7 \pm 0.4$ & $36.3 \pm 1.4$\
& & & & H$\beta$ & 4861.33 & $6.5 \pm 0.2$ & $15.6 \pm 6.2$\

Spectral point spread function subtraction {#sec:SPSF}
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To scan the quasar PSF for hidden objects and recover their spectral signatures in search for the absorbing galaxies, we subtract the quasar continua in a process known as Spectral PSF (SPSF) subtraction [@Moller2000a; @Moller2000b]. Conceptually, a model of the quasar trace in the 2D-spectrum is constructed. The model is then subtracted out to isolate line-emission from objects at small projected separations to the quasar. Variations of SPSF subtraction procedures have been used in prior studies, specifically constructed to find metal emission lines in high-redshift DLA galaxies [@Moller2002; @Fynbo2010; @Zafar2011; @Fynbo2013; @Krogager2013; @Moller2018].

Here, we build a non-parametric, empirical model of the quasar PSF by averaging the observed spatial profile in two spectral windows immediately bluewards and redwards of each predicted emission-line feature for each science frame. We confirm that the quasar trace has no gradient along the dispersion direction 