SEDs for the epochs at TSED1 = 0.003 days and TSED2 = 0.06 days (top), TSED3 = 0.17 days and TSED4 = 0.55 days (middle), and TSED5 = 0.97 days and TSED6 = 1.97 days (bottom). All datasets use photometric data points obtained with Swift UVOT for the low-energy part of the spectrum (red). Error bars represent 1 s.d. Faint dotted lines represent the entire spectral model used, in flux density (Fv) units. The SED is complemented with VLT/X-shooter at day 0.06 (green) and GTC/OSIRIS spectra at day 0.97 and day 1.97 (red), whereas for the X-ray energy range we built specific Swift XRT spectra (black). An additional spectrum is shown in the top-left panel (black data) together with the best-fit results obtained for the Swift windowed-timing (WT) mode spectrum computed at 0.003 days using a black body plus power-law spectral model (solid line).