GRB 100614A SEDs at two different epochs: GTC ugriz upper limits taken 4.3 h after the trigger (upper panels) and the NIR J and K band taken 9.5 h after the trigger (lower panels), with β_OX fixed at β_X − 0.5 (solid red line) and the optical suppression modeled with the MW or starburst extinction curves. Black dotted line represents the best-fit value for the X-ray spectral slope (β_X = 1.50). Dashed red lines enclose the 90% uncertainty in β_OX.