\begin{table}%t4
\caption{\label{tab:13CH3CN} Lower state quantum numbers of rotational transitions 
of $^{13}$CH$_3$CN from present work, 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}{crcrr | crcrr |  crcrr}
\hline \hline
$J''$ & \multicolumn{1}{c}{$K''$} & Frequency & \multicolumn{1}{c}{unc.} & o$-$c & 
$J''$ & \multicolumn{1}{c}{$K''$} & Frequency & \multicolumn{1}{c}{unc.} & o$-$c & 
$J''$ & \multicolumn{1}{c}{$K''$} & Frequency & \multicolumn{1}{c}{unc.} & o$-$c \\
\cline{1-5}  \cline{6-15} 
 18 &  6 &  ~339137.3433  & 1.0 &  $-$0.3  & 43 &  0 &  784895.847   &  50 &      43  &  56 &  3 & 1015544.407   &  20 &      21  \\
 18 &  3 &  ~339309.0082  & 1.0 &     0.3  &  44 & 12 &  800553.654   & 150 &  $-$143  & 56 &  2 & 1015636.946   &  30 &      17  \\
 18 &  2 &  ~339340.8330  & 1.0 &     0.4  &  44 & 11 &  800891.319   & 100 &  $-$105  & 56 &  1 & 1015692.486   &  30 &      17  \\
 18 &  1 &  ~339359.9326  & 1.0 &  $-$0.0  & 44 & 10 &  801200.157   &  50 &      13  & 56 &  0 & 1015711.009   &  50 &      24  \\
 18 &  0 &  ~339366.2998  & 1.0 &  $-$0.4  & 44 &  9 &  801479.794   &  50 &   $-$44  & 57 & 12 & 1030736.928   & 150 &      51  \\
 24 & 12 &  445241.735   &  30 &   $-$11  & 44 &  8 &  801730.374   &  50 &   $-$18 & 57 & 10 & 1031558.219   &  50 &      63  \\
 24 & 11 &  445432.247   &  50 &      73  & 44 &  7 &  801951.637   &  50 &   $-$72  & 57 &  8 & 1032231.921   &  30 &      22  \\
 24 & 10 &  445606.353   &  50 &      51  & 44 &  6 &  802143.651   &  50 &   $-$47  &  57 &  7 & 1032513.150   &  20 &      46  \\
 24 &  9 &  445764.100   &  50 &      41  & 44 &  5 &  802306.261   &  50 &   $-$22  & 57 &  6 & 1032757.054   &  20 &      10  \\
 24 &  8 &  445905.405   &  30 &      22  & 44 &  4 &  802439.367   &  50 &   $-$30  & 57 &  5 & 1032963.632   &  20 &      11  \\
 24 &  7 &  446030.264   &  30 &      48  & 44 &  3 &  802542.979   &  50 &    $-$7  & 57 &  4 & 1033132.760   &  20 &       7  \\
 24 &  6 &  446138.527   &  20 &      19  & 44 &  2 &  802616.938   &  50 &   $-$71  & 57 &  2 & 1033358.435   &  20 &      14  \\
 24 &  5 &  446230.222   &  20 &       8  & 44 &  1 &  802661.445   &  50 &      10  & 57 &  1 & 1033414.879   &  20 &      12  \\
 24 &  4 &  446305.355   &  50 &      56  & 44 &  0 &  802676.201   &  50 &   $-$44  & 57 &  0 & 1033433.720   &  20 &      35  \\
 24 &  3 &  446363.747   &  20 &      17  & 45 &  9 &  819230.822   & 100 &  $-$149  & 60 & 12 & 1083745.465   &  50 &   $-$34  \\
 24 &  2 &  446405.494   &  20 &      11  & 45 &  8 &  819486.798   & 100 &   $-$45  & 60 & 11 & 1084195.000   &  50 &    $-$0  \\
 24 &  1 &  446430.566   &  20 &      24  & 45 &  7 &  819712.787   &  50 &   $-$70  & 60 &  9 & 1084978.318   &  50 &   $-$54  \\
 24 &  0 &  446438.899   &  20 &       3  & 45 &  6 &  819908.940   &  50 &      20  & 60 &  8 & 1085311.933   &  50 &    $-$4  \\
 25 & 12 &  463032.948   &  50 &      70  & 45 &  5 &  820075.010   &  50 &      54  & 60 &  6 & 1085862.162   &  50 &    $-$1  \\
 25 & 11 &  463230.857   &  50 &      42  & 45 &  4 &  820210.775   &  50 &  $-$120  & 60 &  4 & 1086255.771   &  50 &   $-$44  \\
 25 & 10 &  463411.809   &  80 &       2  & 45 &  3 &  820316.536   &  50 &  $-$147  & 60 &  3 & 1086393.678   &  50 &   $-$40  \\
 25 &  9 &  463575.821   &  50 &      38  & 45 &  2 &  820392.237   &  50 &   $-$39  & 60 &  2 & 1086492.216   &  50 &   $-$45  \\
 25 &  6 &  463965.038   &  50 &      45  & 45 &  1 &  820437.489   &  50 &  $-$156  & 61 & 13 & 1100909.779   & 100 &      92  \\
 25 &  5 &  464060.345   &  50 &      31  & 45 &  0 &  820452.748   &  50 &   $-$22  & 61 & 12 & 1101404.872   &  50 &      11  \\
 25 &  4 &  464138.400   &  50 &      41  & 46 &  9 &  836978.116   &  50 &   $-$59  & 61 & 10 & 1102278.334   &  80 &   $-$15  \\
 25 &  3 &  464199.111   &  50 &      18  & 46 &  8 &  837239.242   &  80 &  $-$108  & 61 &  9 & 1102656.306   &  30 &   $-$19  \\
 25 &  2 &  464242.534   &  50 &      42  & 46 &  7 &  837469.939   &  50 &  $-$107  & 61 &  7 & 1103293.992   &  20 &    $-$5  \\
 25 &  1 &  464268.543   &  50 &       3  & 46 &  6 &  837670.126   &  50 &   $-$46  & 61 &  6 & 1103553.424   &  20 &   $-$17  \\
 25 &  0 &  464277.228   &  50 &       5  & 46 &  5 &  837839.510   &  50 &  $-$137  & 61 &  5 & 1103773.128   &  50 &   $-$18  \\
 26 & 13 &  480598.910   & 200 &      15  & 46 &  4 &  837978.301   &  50 &  $-$102  & 61 &  4 & 1103953.032   &  20 &       5  \\
 26 & 12 &  480821.850   & 100 &      20  & 46 &  3 &  838086.283   &  50 &   $-$99  & 61 &  3 & 1104093.012   &  20 &       4  \\
 26 & 10 &  481215.078   &  50 &   $-$26  & 46 &  2 &  838163.526   &  50 &   $-$15  & 61 &  2 & 1104193.040   &  20 &       4  \\
 26 &  9 &  481385.284   &  50 &    $-$5  & 46 &  1 &  838209.741   &  50 &  $-$109  & 61 &  1 & 1104253.061   &  20 &    $-$8  \\
 26 &  8 &  481537.813   &  50 &      67  & 46 &  0 &  838225.208   &  50 &   $-$81  & 61 &  0 & 1104273.082   &  20 &    $-$0  \\
 26 &  7 &  481672.435   &  50 &      22  & 49 & 12 &  889171.685   &  80 &      46  & 62 & 13 & 1118556.496   & 100 &       4  \\
 26 &  6 &  481789.313   &  50 &      78  & 49 & 11 &  889544.894   & 100 &      15  & 62 & 12 & 1119059.047   &  50 &      54  \\
 26 &  5 &  481888.243   & 100 &      77  & 49 & 10 &  889886.195   &  80 &      32  & 62 & 11 & 1119522.099   &  80 &      76  \\
 26 &  4 &  481969.220   &  50 &      55  & 49 &  9 &  890195.361   &  80 &       5  & 62 & 10 & 1119945.421   &  40 &      16  \\
 26 &  3 &  482032.241   &  50 &      42  & 49 &  8 &  890472.317   &  50 &   $-$20  & 62 &  8 & 1120672.581   &  20 &       6  \\
 26 &  2 &  482077.319   &  50 &      78  & 49 &  7 &  890716.982   &  50 &   $-$12  & 62 &  7 & 1120976.075   &  20 &    $-$1  \\
 26 &  1 &  482104.227   &  50 &   $-$48  & 49 &  6 &  890929.260   &  50 &      28  & 62 &  6 & 1121239.357   &  50 &    $-$1  \\
 26 &  0 &  482113.311   &  50 &      24  & 49 &  5 &  891108.967   &  50 &       4  & 62 &  5 & 1121462.318   &  20 &       5  \\
 27 & 12 &  498608.539   & 150 &      24  & 49 &  4 &  891256.131   &  50 &      16  & 62 &  3 & 1121786.918   &  20 &      12  \\
 27 & 11 &  498821.247   & 150 &  $-$178  & 49 &  3 &  891370.650   &  50 &      21  & 62 &  2 & 1121888.415   &  20 &       1  \\
 27 & 10 &  499016.263   & 100 &     151  & 49 &  2 &  891452.462   &  50 &       5  & 62 &  1 & 1121949.341   &  20 &       7  \\
 27 &  8 &  499350.520   &  50 &      18  & 49 &  1 &  891501.579   &  50 &      12  & 62 &  0 & 1121969.656   &  30 &      12  \\
 27 &  7 &  499490.120   &  50 &      47  & 49 &  0 &  891517.973   &  50 &      33  & 63 & 15 & 1135059.113   & 150 &      40  \\
 27 &  6 &  499611.153   &  50 &       4  & 50 & 13 &  906470.254   & 150 &      42  & 63 & 11 & 1137177.559   &  50 &    $-$3  \\
 27 &  5 &  499713.686   &  50 &       4  & 50 & 12 &  906882.928   &  50 &       9  & 63 & 10 & 1137607.095   &  30 &       4  \\
 27 &  4 &  499797.648   &  50 &      17  & 50 & 11 &  907263.229   &  80 &      15  & 63 &  9 & 1137996.224   &  20 &    $-$3  \\
 27 &  2 &  499909.654   &  50 &      11  & 50 & 10 &  907610.895   & 100 &   $-$53  & 63 &  8 & 1138344.827   &  50 &       9  \\
 27 &  1 &  499937.687   &  50 &      27  & 50 &  9 &  907925.987   &  50 &       1  & 63 &  7 & 1138652.740   &  20 &      15  \\
 27 &  0 &  499947.025   &  50 &      24  & 50 &  8 &  908208.205   &  50 &       3  & 63 &  6 & 1138919.837   &  20 &       8  \\
 28 & 11 &  516613.238   &  80 &      10  & 50 &  7 &  908457.487   &  80 &       4  & 63 &  5 & 1139146.023   &  20 &       2  \\
 28 & 10 &  516814.764   &  80 &      23  & 50 &  6 &  908673.729   &  50 &    $-$2  & 63 &  4 & 1139331.185   &  50 &   $-$27  \\
 28 &  9 &  516997.294   &  50 &   $-$16  & 50 &  5 &  908856.837   &  50 &   $-$22  & 63 &  3 & 1139475.324   &  20 &    $-$2  \\
 28 &  3 &  517691.313   &  50 &      22  & 50 &  4 &  909006.769   &  50 &   $-$23  & 63 &  2 & 1139578.300   &  20 &    $-$7\\ 
 \hline  
 28 &  2 &  517739.642   &  50 &      31  & 50 &  3 &  909123.446   &  50 &   $-$23  & 63 &  1 & 1139640.092   &  20 &   $-$19  \\
 28 &  1 &  517768.629   &  50 &      19  & 50 &  2 &  909206.838   &  50 &    $-$7  & 64 & 14 & 1153276.801   & 200 &     131  \\
 28 &  0 &  517778.310   &  50 &      31  & 50 &  1 &  909256.926   &  50 &      43  & 64 & 12 & 1154351.199   &  30 &   $-$21  \\
 34 & 16 &  621760.772   &  50 &      10  & 50 &  0 &  909273.539   &  50 &   $-$26  & 64 &  9 & 1155657.985   &  20 &   $-$18  \\
 34 & 14 &  622447.422   &  30 &   $-$26  & 51 & 12 &  924589.926   &  80 &      22  & 64 &  8 & 1156011.566   &  20 &       4  \\
 34 & 11 &  623309.671   &  20 &      14  & 51 & 11 &  924977.218   & 100 &   $-$13  & 64 &  7 & 1156323.830   &  20 &   $-$27  \\
 34 & 10 &  623551.857   &  20 &       5  & 51 &  9 &  925652.265   &  50 &       8  & 64 &  6 & 1156594.758   &  20 &    $-$9  \\
 34 &  9 &  623771.262   &  20 &   $-$14  & 51 &  8 &  925939.684   &  50 &    $-$7  & 64 &  4 & 1157012.016   &  20 &       5  \\
 34 &  7 &  624141.443   &  20 &   $-$28  & 51 &  7 &  926193.576   &  80 &    $-$5  & 64 &  3 & 1157158.166   &  20 &   $-$13  \\
 34 &  6 &  624292.087   &  20 &    $-$5  & 51 &  5 &  926600.341   &  80 &       2  & 64 &  2 & 1157262.634   &  20 &       8  \\
 34 &  4 &  624524.053   &  20 &   $-$26  & 51 &  4 &  926753.052   &  80 &       8  & 64 &  0 & 1157346.208   &  20 &    $-$2  \\
 34 &  2 &  624663.446   &  20 &      24  & 51 &  3 &  926871.878   &  50 &    $-$0  & 65 & 13 & 1171464.851   & 100 &      10  \\
 34 &  1 &  624698.263   &  20 &   $-$13  & 51 &  2 &  926956.781   &  50 &   $-$14  & 65 & 11 & 1172472.160   &  80 &  $-$102  \\
 34 &  0 &  624709.879   &  20 &   $-$16  & 51 &  1 &  927007.756   &  50 &    $-$2  & 65 &  9 & 1173314.209   &  30 &    $-$5  \\
 35 & 16 &  639490.666   & 100 &      54  & 51 &  0 &  927024.756   &  50 &       8  & 65 &  8 & 1173672.712   &  20 &    $-$8  \\
 35 & 14 &  640196.404   &  60 &      27  & 55 & 12 &  995373.248   & 100 &      44  & 65 &  6 & 1174264.072   &  20 &   $-$12  \\
 35 & 12 &  640810.267   &  30 &   $-$44  & 55 & 10 &  996168.138   & 100 &      60  & 65 &  4 & 1174687.142   &  50 &   $-$23  \\
 35 & 11 &  641082.493   &  50 &   $-$47  & 55 &  9 &  996511.966   &  50 &   $-$72  & 65 &  3 & 1174835.374   &  20 &    $-$3  \\
 35 &  9 &  641556.961   &  50 &   $-$22  & 55 &  7 &  997092.349   &  20 &      21  & 65 &  2 & 1174941.285   &  20 &    $-$1  \\
 35 &  7 &  641937.464   &  20 &       1  & 55 &  5 &  997528.396   &  20 &      33  & 65 &  1 & 1175004.858   &  20 &       9  \\
 35 &  6 &  642092.248   &  50 &   $-$20  & 55 &  4 &  997692.055   &  20 &    $-$4  & 65 &  0 & 1175026.016   &  30 &   $-$23  \\
 35 &  5 &  642223.312   &  50 &   $-$53  & 55 &  3 &  997819.444   &  30 &    $-$3  & 66 & 12 & 1189621.606   & 120 &     111  \\
 35 &  4 &  642330.670   &  30 &   $-$28  & 55 &  2 &  997910.473   &  20 &    $-$2  & 66 & 11 & 1190111.236   & 150 &   $-$17  \\
 35 &  3 &  642414.174   &  50 &   $-$52  & 55 &  1 &  997965.147   &  30 &      40  & 66 & 10 & 1190558.963   & 120 &  $-$107  \\
 35 &  2 &  642473.884   &  30 &   $-$29  & 55 &  0 &  997983.325   &  20 &       6  & 66 &  9 & 1190964.780   &  20 &       6  \\
 35 &  0 &  642521.653   &  30 &   $-$24  & 56 & 12 & 1013057.279   & 100 &  $-$164  & 66 &  6 & 1191927.684   &  25 &   $-$10  \\
 43 &  8 &  783970.101   &  80 &      18  & 56 &  9 & 1014215.234   &  20 &       7  & 66 &  5 & 1192163.522   &  20 &       8  \\
 43 &  6 &  784374.602   &  50 &      11  & 56 &  8 & 1014528.429   &  50 &   $-$48  & 66 &  4 & 1192356.610   &  20 &      23  \\
 43 &  5 &  784533.705   &  50 &   $-$10  & 56 &  7 & 1014805.211   &  20 &      40  & 66 &  3 & 1192506.829   &  20 &    $-$6  \\
 43 &  3 &  784765.344   &  50 &   $-$36  & 56 &  6 & 1015045.237   &  30 &      40  & 66 &  2 & 1192614.182   &  20 &   $-$17  \\
 43 &  2 &  784837.839   &  50 &      11  & 56 &  5 & 1015248.484   &  20 &      23  & 66 &  1 & 1192678.616   &  20 &   $-$19  \\
 43 &  1 &  784881.204   &  50 &  $-$104  & 56 &  4 & 1015414.879   &  20 &    $-$1  & 66 &  0 & 1192700.114   &  20 &    $-$2  \\
 \hline  \end{tabular} 
 \end{table}