\begin{table}%t1
\caption{\label{SWIFT_tab}Observation log and fitting results of {\it Swift}/XRT observations of PKS 1510-089, with power-law model with $N_{\rm H}$ fixed to Galactic absorption.}
%\centerline
 {\small 
\begin{tabular}{cccccc}
\hline \hline
\noalign{\smallskip}
\multicolumn{1}{c}{Observation} & \multicolumn{1}{c}{Exposure time} &
\multicolumn{1}{c}{Counts} & \multicolumn{1}{c}{Flux 0.3--10~keV$^{a}$} &
\multicolumn{1}{c}{Photon index} & \multicolumn{1}{c}{$ \chi^{2}_{\rm red}$ (d.o.f.)/C-stat ($\%$)$^{b}$} \\
\multicolumn{1}{c}{date} & \multicolumn{1}{c}{ (s) } &
\multicolumn{1}{c}{ (0.2--10~keV) } & \multicolumn{1}{c}{erg~cm$^{-2}$~s$^{-1}$} & \multicolumn{1}{c}{$\Gamma$}&
\multicolumn{1}{c}{} \\
\hline
\noalign{\smallskip}
20-Mar-2008 & 1961 & 306 & $12.20 _{-1.65}^{+1.65} \times 10^{-12}$ & $1.16 \pm 0.16$ & 0.87 (13)\\
21-Mar-2008 & 1966 & 189 & $8.77_{-1.39}^{+1.33} \times 10^{-12}$ & $1.53 \pm 0.17$ &  467
(48.2)$^{b}$\\
22-Mar-2008 & 1885 & 261 & $9.48 _{-1.14}^{+1.13} \times 10^{-12}$ & $1.41 \pm 0.19$ & 1.34
(11) \\
\hline
\end{tabular}}
\medskip
$^a$ Unabsorbed flux; $^b$~cash statistic (C-stat) and percentage of Montecarlo realizations that had  statistic $<$ C-stat, performing 10$^4$ simulations. 
\end{table}