\begin{table}%t3
%tab.3
%\centering
\par
\caption{Correlation coefficients, $r_{\rm c}$, slopes and $\chi^2$ of the linear fits to the scatter plots of modelled total solar irradiance based on NSO-512 and NSO-SPM data vs. PMOD composite measurements for different periods. The reconstructed TSI values are calculated with different conversion factors between NSO-512 and NSO-SPM magnetograms in the upper and lower halves of the table.}
\label{tab:3}
\begin{tabular}{c@{  }ccccc}
\hline
\hline
Time period & Magnetogram & $B_{\rm sat}/[{\rm G}]$ & $r_{\rm c}$ & Slope & $\chi^2$  \\
\hline
 &  Standard reconstructions (Sect.~\ref{sec:comppmod})\\
%\hline
1978--2003 & NSO-512/1.46 and NSO-SPM & 340 & 0.89 & $1.003 \pm 0.009$ & 0.077 \\
1978--1992 & NSO-512/1.46 & 340 & 0.88 & $1.023 \pm 0.015$ & 0.111 \\
1992--2003 & NSO-SPM & 340 & 0.93 & $0.937 \pm 0.008$ & 0.031 \\
\hline
 &  Optimized reconstructions (Sect.~\ref{sec:compoptimal})\\
%\hline
1978--2003 & NSO-512/1.6 and NSO-SPM & 320 & 0.91 & $0.978 \pm 0.008$ & 0.056 \\
1978--1992 & NSO-512/1.6 & 320 & 0.89 & $0.968 \pm  0.014$ & 0.091 \\
1992--2003 & NSO-SPM & 320 & 0.94 & $0.983 \pm 0.008$ & 0.032 \\
\hline
\end{tabular}
\end{table}