\begin{table}%t2
\caption{\label{log_observaciones}Observation log.}
%%\centering

\par
\begin{tabular}{ccccccccc}
\hline\hline \noalign{\smallskip}
Grating & Spectral range & Resolution & $t_{{\rm exp}}$ & Airmass\\
        &  (\AA)         &              & (s)        &      \\
\hline
L682.2    & 6438--7184 & 13~700 & $5\times1500$ &  1.75--1.13\\
L479.7    & 4501--5078 & 12~000 & $5\times1500$ &  1.11--1.01\\
\hline
\end{tabular}
\end{table}