[C II] channel maps of J2310+1855. The velocity takes the [C II] redshift from Wang et al. (2013) as a reference. The channel width is ∼ 17 km/s (corresponding to 15.625 MHz). The contour levels are [−2, 2, 4, 6, 8, 10, 12, 14] × rms, where rms = 0.17 mJy/beam. The white plus sign represents the HST quasar position. The [C II] emission peak moves in a circular, counterclockwise path from 219 to −281 km/s.