used both to estimate the point-spread function and to correct for transparency variations. The position of was fixed with respect to the position of the comparison star; this ensures that centroiding on the faint GRB does not introduce spurious variability into the light curve. Observations of a flux standard were taken on the following night to place the measurements on a standard photometric system. We were not able to determine the $V$-band extinction coefficient for the night of these observations, so the La Silla average of 0.12 mag/airmass was used to correct for atmospheric extinction. The observation log is presented in Table \[tab1\].\

VLT/FORS2 observations
----------------------

Starting at 08:32 UT on 2008 February 10th (42 min post-burst), a series of 600s spectra were obtained with VLT/FORS2 in long-slit spectroscopy mode with a 10 wide slit, North-South oriented and centred with an $R$-band acquisition image. The sequence of grisms used was 300V, 600z+OG590, 1400V, 1200R+GG435 and finally 300V again. This allowed us to both cover a larger wavelength window with the lower resolution grism (300V) and obtain mid-resolution spectroscopy for different regions of the spectrum. The individual spectra were cleaned of cosmic rays using the Laplacian Cosmic Ray Identification algorithm of 