Spectra extracted from circular apertures (r = 0.6″) centred on the sources shown in the insets. The vertical blue lines mark the emission lines; in the last panel, Balmer and CaII absorption features around 3800 Å are marked with red lines. For each target, we report the spectroscopic redshift, the coordinates, and, for the sources in the DECaLS Survey (Dey et al. 2018), the optical magnitudes. The insets show the [OII] emission maps (with an FOV of 8″ × 8″).