MOSFIRE K-band spectrum of Q1549-C25. The spectrum is presented in the observed frame and the flux-density units are ﹩{10}^{-18}\,{\text{erg s}}^{-1}\,{{\rm{cm}}}^{-2}\,{{\rm{\mathring{\rm A} }}}^{-1}﹩. The error spectrum is plotted in red. The [O III]λ5007 and [O III]λ 4959 lines are clearly detected, while Hβ falls on a sky line. The combined [O III]+Hβ emission-line flux is ﹩\leqslant 5.2\times {10}^{-17}\,{\text{erg s}}^{-1}\,{{\rm{cm}}}^{-2}﹩, corresponding to a rest-frame equivalent width of ﹩{W}_{([{\rm{O}}{\rm{iii}}]+{\rm{H}}\beta ),0}\leqslant 256﹩ Å. The systemic redshift based on [O III] emission is z_sys = 3.1526.