Results of modelling the photometry for HD1 with MAGPHYS. Top panels: best-fit SEDs for different potential redshift solutions, indicated by the legend at the top left, with the residuals shown below. The z ∼ 3.8 and z = 4.6 solutions correspond to a passive galaxy where the drop in flux is due to the Balmer break. The best intermediate-redshift fit to the limited available data is for z = 3.8. In this scenario, the Band 6 data would cover CO(10−9), which we do not expect to be detected for such a passive galaxy (see text). The highest redshift solution within the range probed by the Band 6 data (12.6 < z < 14.3) provides the best fit overall. The single redshift solution between z = 4 and 13 for which the two ≳3σ features could physically correspond to lines, z = 6.76, is a much poorer fit to the photometry. Bottom panels: likelihood distributions for the different fit parameters, colour-coded according to the legend in the top panel.