\begin{table}%t8
\caption{\label{tab:2x13} Lower state quantum numbers of rotational transitions 
of $^{13}$CH$_3^{13}$CN, frequencies (MHz), uncertainties unc. (kHz), and 
residuals o$-$c (kHz) between observed frequencies and those calculated from 
the final set of spectroscopic parameters.} 
\par
%\centerline
{
\small\begin{tabular}{cccrr |cccrr | ccrrr}
\hline \hline
$J''$ & $K''$ & Frequency & \multicolumn{1}{c}{unc.} & o$-$c &
$J''$ & $K''$ & Frequency & \multicolumn{1}{c}{unc.} & o$-$c &
$J''$ & $K''$ & Frequency & \multicolumn{1}{c}{unc.} & o$-$c \\
\hline
 13 & 4 &  249849.289 &  30 &    30 & 18 & 5 &  338978.878 &  50 &     2 & 51 & 2 &  926328.788 & 200 &$-$108 \\
 13 & 3 &  249881.971 &  10 &  $-$5 & 18 & 2 &  339111.819 &  15 &  $-$6 & 51 & 1 &  926379.428 & 200 &$-$194 \\
 14 & 4 &  267689.340 &  20 &  $-$8 & 25 & 3 &  463885.870 &  50 &    22 & 54 & 3 &  979425.780 & 150 &    20 \\
 14 & 3 &  267724.401 &  10 &     9 & 25 & 2 &  463929.028 &  50 & $-$11 & 60 & 6 & 1085127.880 & 150 &    34 \\
 14 & 2 &  267749.425 &  10 &  $-$7 & 27 & 3 &  499525.679 & 100 &    88 & 60 & 4 & 1085519.654 & 150 & $-$68 \\
 14 & 1 &  267764.473 &  15 &    12 & 34 & 7 &  623721.761 & 200 & $-$22 & 60 & 3 & 1085656.847 & 200 &$-$150 \\
 15 & 6 &  285421.490 &  40 &    21 & 34 & 5 &  623998.639 & 150 & $-$25 & 60 & 0 & 1085833.407 & 200 &$-$177 \\
 15 & 4 &  285528.155 &  30 &    18 & 34 & 4 &  624102.519 & 150 & $-$85 & 61 & 9 & 1101913.821 & 100 & $-$11 \\
 15 & 3 &  285565.500 &  15 &  $-$4 & 34 & 3 &  624183.422 & 100 & $-$68 & 61 & 5 & 1103025.791 & 150 &    69 \\
 15 & 2 &  285592.188 &  15 & $-$17 & 34 & 2 &  624241.332 &  50 &    45 & 61 & 4 & 1103204.664 & 150 &$-$125 \\
 15 & 1 &  285608.237 &  30 &     7 & 35 & 9 &  641127.171 & 200 &   161 & 61 & 2 & 1103443.760 & 150 &    55 \\
 16 & 6 &  303252.220 &  25 & $-$24 & 35 & 3 &  641980.261 &  80 & $-$29 & 61 & 1 & 1103503.550 & 150 &    88 \\
 16 & 1 &  303450.598 &  15 &  $-$8 & 35 & 1 &  642075.314 &  80 & $-$31 & 62 & 6 & 1120480.948 & 200 &   154 \\
 17 & 6 &  321081.547 &  15 &  $-$6 & 50 & 3 &  908507.997 & 150 & $-$88 & 62 & 4 & 1120884.433 & 200 & $-$34 \\
 17 & 5 &  321147.495 &  20 &     9 & 50 & 2 &  908591.195 & 150 &   123 & 62 & 3 & 1121025.872 & 100 &  $-$3 \\
 17 & 4 &  321201.474 &  15 &     8 & 50 & 0 &  908657.612 & 150 &   132 & 62 & 2 & 1121126.880 & 150 & $-$39 \\
 17 & 3 &  321243.472 &   5 &  $-$0 & 51 & 6 &  925788.347 & 200 & $-$80 & 63 & 2 & 1138804.705 & 200 &    60 \\
 17 & 2 &  321273.504 &  10 &    15 & 51 & 3 &  926244.313 & 200 & $-$61 & 63 & 1 & 1138866.331 & 200 &   163 \\
 17 & 1 &  321291.490 &  15 & $-$13 &    &   &        &     &     &       &    &   &        &            \\
\hline  
\end{tabular}} 
\end{table}