English: For display purposes, the data have been smoothed using a Savitzky-Golay filter (solid black line), and the unfiltered data are shown in grey. A predicted model macronova spectrum (23) assuming an ejecta mass of Mej = 0.05M☉ and a velocity of v = 0.1c at a phase of 4.5 days post merger is shown in red. The spectra have been corrected for Milky Way extinction assuming reddening E(B – V) = 0.1 (10). Regions of low signal-to-noise ratio from strong telluric absorption by the Earth’s atmosphere between the near-infrared J, H, and K spectral windows are indicated by the vertical dark grey bars. The light grey shaded band is the blackbody which best fits the photometric measurements at 4.5 days (10).