  We present the optical to near-infrared spectrum of MAXI J1659-152, during
the onset of its 2010 X-ray outburst. The spectrum was obtained with X-shooter
on the ESO - Very Large Telescope (VLT) early in the outburst simultaneous with
high quality observations at both shorter and longer wavelengths. At the time
of the observations, the source was in the low-hard state. The X-shooter
spectrum includes many broad (~2000 km/s), double-peaked emission profiles of
H, HeI, HeII, characteristic signatures of a low-mass X-ray binary during
outburst. We detect no spectral signatures of the low-mass companion star. The
strength of the diffuse interstellar bands results in a lower limit to the
total interstellar extinction of Av ~ 0.4 mag. Using the neutral hydrogen
column density obtained from the X-ray spectrum we estimate Av ~1 mag. The
radial-velocity structure of the interstellar NaI D and CaII H & K lines
results in a lower limit to the distance of ~ 4 +/- 1 kpc, consistent with
previous estimates. With this distance and Av, the dereddened spectral energy
distribution represents a flat disk spectrum. The two subsequent 10 minute
X-shooter spectra show significant variability in the red wing of the
emission-line profiles, indicating a global change in the density structure of
the disk, though on a timescale much shorter than the typical viscous timescale
of the disk.
