CO(3−2) maps (top panels) of serendipitous sources detected in the HB8903 field of view. The maps are obtained collapsing under golden shade region shown in their respective spectra (bottom panels). Black contours contours are in steps of 1σ = 0.03 Jy/beam km s^-1 for the source A and 1σ = 0.04 Jy/beam km s^-1 for the source B, starting at ± 2σ. The ALMA beam is shown in the bottom-right corner of each map. The white solid (dashed) contours indicate the continuum emission at levels of 2(− 2) and 3(− 3) times the noise per beam (18 μJy/beam). The spectra in the bottom panels are extracted from the centre of the sources. The 0 km s^-1 corresponds into the redshift of HB8903.