2D grism spectrum of COLA1 in the regions where the most luminous lines are visible. The three rows of panels on the left side of the figure contain the EMLINE fluxes of modules A and B, as well as the average flux of both modules. The x axis shows the rest-frame wavelength assuming a redshift of z = 6.59165. The right panel displays the false-color NIRCam image of COLA1, oriented with our position angle of 295 deg. We note that the blue extended ‘tail’ is a B-band detected foreground contaminant at z ≤ 2.5 (see Appendix B; see also Matthee et al. 2018).