GROND optical/NIR and XRT 0.3−10 keV light curves of the afterglow of GRB 120815A in the top panel. The data were fitted with a three-segment, smoothly broken power-law, with residuals shown in the bottom panel. The grey shaded area represents the time interval in which the X-shooter spectroscopy was obtained. X-ray data were converted into a flux density at 3 keV using a spectral index of β = 0.78, and scaled by a factor of 20 to enhance clarity.

X-shooter UVB-arm spectrum of the afterglow of GRB 120815A. Black lines show the spectral data, grey lines the noise level, the green line is the GRB afterglow model, and the red-line shows the DLA modeling. The position of absorption lines that are typically associated with GRB-DLAs (taken from Christensen et al. 2011) are indicated by brown lines and ions. Individual lines associated with intervening absorbers are labeled with colored lines and labels.

X-shooter VIS-arm spectrum of the afterglow of GRB 120815A. Lines and labels are the same as in Fig. B.1. Additionally, strong telluric lines are indicated by circles in the upper part of each panel.

X-shooter NIR-arm spectrum of the afterglow of GRB 120815A. Lines and labels are the same as in Fig. B.2.

X-shooter spectrum between 4100 and 5600 Å showing the presence of H lines. The uppermost, blue-framed panel shows an overview over the whole spectral range, while the lower 5 panels zoom in of 180 Å each. We selected regions where most of the absorption bands of H are located. Light-grey lines always show the normalized spectrum, while dark-grey lines indicate the error spectrum. Red lines denote the best-fit H model. In the top panel, we also mark prominent metal absorption lines previously detected in GRB-DLAs (Christensen et al. 2011). In the lower panels, several individual H transitions are identified using standard nomenclature with lower and upper vibrational and rotational quantum numbers.