\begin{table} %t4
\caption{Observed and modeled depolarization of synchrotron emission 
in several regions of NGC~4254 due to differential Faraday rotation, Faraday 
dispersion, and gradients in $RM$. The regions are marked in Fig.~\ref{f:magmaps}b.
}
\small%\centering
\par
\begin{tabular}{lrrrr}
\hline
\hline
                          & Obs. $DP$(3.6/6.3) & Diff. FR      & Far. Disp.    & Grad. $RM$  \\
\hline                                                      
1) Southern outer magnetic arm & $1.08\pm0.02$ & $ 0.99\pm0.01$ & $0.99\pm0.01$ & $0.99\pm0.01$ \\
2) Western outer magnetic arm  & $1.14\pm0.14$ & $ 0.97\pm0.02$ & $1.00\pm0.01$ & $0.98\pm0.01$ \\
3) Northern inner magnetic arm & $1.04\pm0.17$ & $ 0.99\pm0.01$ & $1.00\pm0.01$ & $0.98\pm0.01$ \\
4) Central part                & $0.57\pm0.18$ & $ 0.66\pm0.28$ & $0.70\pm0.04$ & $0.91\pm0.11$ \\
5) SW optical spiral arm       & $0.89\pm0.04$ & $ 0.99\pm0.01$ & $0.86\pm0.06$ & $0.99\pm0.01$ \\
6) NE optical spiral arm       & $0.72\pm0.15$ & $ 0.91\pm0.07$ & $0.89\pm0.15$ & $0.94\pm0.04$ \\
\hline  
\label{t:depo}
\end{tabular} 
\end{table}