\begin{table}%t3
\caption{Power spectral fit results. As a model independent 
measure of the variability we also include the total fractional rms in the
0.001--1~Hz and 1--100~Hz ranges. {\it FWHM} stands for \mbox{full-width-at-half-maximum}.}\label{tab_pds}
%\centerline
{
\begin{tabular}{lcc}
\hline
\hline
Parameter                  & Obs. 1 & Obs. 2 \\
\hline
Power law rms$^a$ (\%)     & 5.15 $\pm$ 0.12	     & 7.71 $\pm$ 0.11 \\
Power law index            & 1.09 $\pm$ 0.01	     & 1.09 $\pm$ 0.01 \\
Lorentzian rms$^b$ (\%)    & 2.99 $\pm$ 0.01           & 3.4 $\pm$ 0.6 \\
Lorentzian FWHM (\%)       & 0.45 $\pm$ 0.04           & 100 $\pm$ 30 \\
Lorentzian freq. (Hz)      & 0 {\it (fixed)}         & 0 {\it (fixed)} \\
QPO rms$^c$ (\%)           & $<$1                    & 2.1 $\pm$ 0.4 (3.2$\sigma$)$^d$ \\
QPO FHWM (Hz)              & 18 {\it (fixed)}        & 18 $\pm$ 6 \\
QPO frequency (Hz)         & 60 {\it (fixed)}        & 60 $\pm$ 2 \\
rms [0.001--1 Hz] (\%)     & 6.6 $\pm$ 0.02            & 9.15 $\pm$ 0.02 \\
rms [1--100 Hz]   (\%)     & 3.17 $\pm$ 0.10           & 5.93 $\pm$ 0.06 \\
$\chi^2_{{\rm red}} ({\rm d.o.f.})$       & 1.07 (209)                & 1.01 (210)  \\
\hline
\end{tabular}}
\medskip
$^a$ Integrated between 0.001 and 1 Hz; $^b$ Integrated between~0 and $+\infty$~Hz; $^c$ Integrated between~$-\infty$ and~$+\infty$~Hz; $^d$~Significance is calculated from the power, not the fractional~rms.  
\end{table}