Left panel: the total flux (gray), extended Lyα (red), and 1σ error (blue) extracted over the 2D spatial mask as described in Section 3.1. The vertical dotted line denotes the expected wavelength of Lyα at the quasar’s [C II] redshift. The black arrow marks the location of N V. The purple band displays the spectral range ﹩({\lambda }_{{\rm{\min }}},{\lambda }_{{\rm{\max }}})﹩ over which extended Lyα was detected. The orange bands show the spectral ranges used to create the PSF model. Right panel: total flux density, extended Lyα, and 1σ error as a function of the velocity offset relative to Lyα at the quasar’s [C II] redshift. The black arrow indicates the Lyα velocity centroid of the halo.