\begin{table} %\centering \par \caption {\label{SiC2-lines}Observed SiC$_2$ transitions $J^u$$_{\rm Ka,Kc}-J^l$$_{\rm Ka,Kc}$. } \begin{tabular}{ccrccc} \hline\hline \noalign{\smallskip} Transition & Obs. Freq. & $\rm o-c$ &$S$& $E_{\rm{l}}$/k& $I_{\varv}$\\ $J^u$$_{\rm Ka,Kc}-J^l$$_{\rm Ka,Kc}$ & (MHz) & (MHz)& & (K)& (K km~s$^{-1}$)\\ \hline\\[-2ex] 24$_{~~2,22}$--23$_{~~2,21}$ &557109.0(1.5)& 1.43& 23.5 & 328.2 & 1.42( 3)\\ 24$_{12,13}$--23$_{12,12}$ &557600.0(1.5)& 0.27& 18.0 & 589.7 & 0.32( 3)\\ 24$_{12,12}$--23$_{12,11}$ &557600.0(1.5)& 0.27& 18.0 & 589.7 & 0.32( 3)\\ 24$_{10,15}$--23$_{10,14}$ &562069.0(5.0)& $-$1.09& 19.9 & 505.2 & 0.45(11)\\ 24$_{10,14}$--23$_{10,13}$ &562069.0(5.0)& $-$1.09& 19.9 & 505.2 & 0.45(11)\\ 24$_{~~8,17}$--23$_{~~8,16}$ &566903.0(6.0)& 7.29& 21.4 & 436.6 & 0.74( 5)\\ 24$_{~~8,16}$--23$_{~~8,15}$ &566912.0(6.0)& 9.90& 21.4 & 436.6 & 0.74( 5)\\ 24$_{~~4,21}$--23$_{~~4,20}$ &568464.0(1.5)& $-$0.55& 23.3 & 346.2 & 1.25( 2)\\ 25$_{16,10}$--24$_{16,~~9}$ &571113.0(6.0)& 2.06& 14.8 & 832.7 & 0.14( 3)\\ 25$_{16,~~9}$--24$_{16,~~8}$ &571113.0(6.0)& 2.06& 14.8 & 832.7 & 0.14( 3)\\ 23$_{~~4,19}$--22$_{~~4,18}$ &571141.0(1.5)& 2.43& 22.4 & 324.6 & 1.46( 2)\\ 24$_{~~6,19}$--23$_{~~6,18}$ &572966.0(1.5)& 2.02& 22.5 & 384.1 & 0.90( 2)\\ 27$_{~~0,27}$--26$_{~~0,26}$ &573938.0(1.5)& $-$0.07& 26.9 & 364.7 & 1.48( 2)\\ 26$_{~~2,25}$---25$_{~~2,24}$ &574425.0(1.5)& 1.53& 25.7 & 361.9 & 1.27( 2)\\ 24$_{~~6,18}$-23$_{~~6,17}$ &574577.0(1.5)& 3.70& 22.5 & 384.2 & 1.02( 2)\\ 25$_{14,12}$--24$_{14,11}$ &576122.0(6.0)& $-$3.08& 17.2 & 716.6 & 0.13( 3)\\ 25$_{14,11}$--24$_{14,10}$ &576122.0(6.0)& $-$3.08& 17.2 & 716.6 & 0.13( 3)\\ 25$_{~~2,23}$-24$_{~~2,22}$ &577234.0(1.5)& 0.69& 24.5 & 355.0 & 1.39( 2)\\ 25$_{12,14}$--24$_{12,13}$ &580951.0(1.5)& 0.97& 19.3 & 616.4 & 0.31( 2)\\ 25$_{12,13}$--24$_{12,12}$ &580951.0(1.5)& 0.97& 19.3 & 616.4 & 0.31( 2)\\ 25$_{10,16}$--24$_{10,15}$ &585735.0(1.5)& $-$0.44& 21.0 & 532.2 & 0.44( 2)\\ 25$_{10,15}$--24$_{10,14}$ &585735.0(1.5)& $-$0.44& 21.0 & 532.2 & 0.44( 2)\\ 25$_{~~8,18}$--24$_{~~8,17}$ &590972.0(2.5)& 0.41& 22.5 & 463.8 & 0.66( 2)\\ 25$_{~~4,22}$--24$_{~~4,21}$ &590814.0(1.5)& $-$1.58& 24.3 & 373.5 & 1.09( 1)\\ 25$_{~~8,17}$--24$_{~~8,16}$ &590990.0(2.5)& 3.89& 22.5 & 463.8 & 0.66( 2)\\ 28$_{~~0,28}$--27$_{~~0,27}$ &594745.0(1.5)& $-$0.57& 27.9 & 392.2 & 1.46( 3)\\ 27$_{~~2,26}$--26$_{~~2,25}$ &595235.0(1.5)& 2.63& 26.7 & 389.4 & 1.43( 3)\\ 24$_{~~4,20}$--23$_{~~4,19}$ &596691.0(1.5)& 0.51& 23.4 & 352.0 & 1.76( 2)\\ 25$_{~~6,20}$--24$_{~~6,19}$ &597462.0(5.0)& $-$0.07& 23.6 & 411.6 & 0.86( 4)\\ 26$_{~~2,24}$--25$_{~~2,23}$ &597477.0(2.5)& $-$0.93& 25.5 & 382.7 & 1.10( 4)\\ 26$_{14,13}$--25$_{14,12}$ &599184.0(4.0)& $-$9.03& 18.5 & 744.2 & 0.14( 2)\\ 26$_{14,12}$--25$_{14,11}$ &599184.0(4.0)& $-$9.03& 18.5 & 744.2 & 0.14( 2)\\ 25$_{~~6,19}$--24$_{~~6,18}$ &599914.0(1.5)& 0.11& 23.6 & 411.8 & 0.85( 2)\\ 26$_{12,14}$--25$_{12,13}$ &604324.0(6.0)& 7.38& 20.5 & 644.3 & 0.38( 3)\\ 26$_{12,15}$--25$_{12,14}$ &604324.0(6.0)& 7.38& 20.5 & 644.3 & 0.38( 3)\\ 26$_{10,16}$--25$_{10,15}$ &609433.0(1.5)& $-$0.94& 22.2 & 560.3 & 0.47( 1)\\ 26$_{10,17}$--25$_{10,16}$ &609433.0(1.5)& $-$0.94& 22.2 & 560.3 & 0.47( 1)\\ 26$_{~~4,23}$--25$_{~~4,22}$ &612914.0(1.5)& $-$0.82& 25.3 & 401.8 & 1.09( 1)\\ 26$_{~~8,19}$--25$_{~~8,18}$ &615115.0(4.0)& $-$0.21& 23.6 & 492.2 & 0.78( 2)\\ 26$_{~~8,18}$--25$_{~~8,17}$ &615139.0(4.0)& 2.45& 23.6 & 492.2 & 0.70( 2)\\ 27$_{16,12}$--26$_{16,11}$ &616666.0(6.0)& $-$1.46& 17.6 & 888.7 & 0.06( 1)\\ 27$_{16,11}$--26$_{16,10}$ &616666.0(6.0)& 5.55& 17.6 & 888.7 & 0.06( 1)\\ 29$_{~~0,29}$--28$_{~~0,28}$ &615547.0(1.5)& 5.55& 28.9 & 420.8 & 1.55( 2)\\ 27$_{~~2,25}$--26$_{~~2,24}$ &617833.0(1.5)& 0.71& 26.5 & 411.3 & 1.15( 2)\\ 25$_{~~4,21}$--24$_{~~4,20}$ &621588.0(1.5)& $-$1.38& 24.5 & 380.6 & 1.36( 2)\\ 26$_{~~6,21}$--25$_{~~6,20}$ &621960.0(1.5)& 0.96& 24.7 & 440.3 & 0.91( 2)\\ 27$_{14,14}$--26$_{14,13}$ & 622264.0(6.0)& $-$1.00& 19.8 & 773.0 & 0.11( 1)\\ 27$_{14,13}$--26$_{14,12}$ & 622264.0(6.0)& $-$1.00& 19.8 & 773.0 & 0.11( 1)\\ 26$_{~~6,20}$--25$_{~~6,19}$ &625591.0(1.5)& $-$1.43& 24.7 & 440.6 & 1.06( 2)\\ 27$_{12,16}$--26$_{12,15}$ & 627699.0(1.5)& $-$0.23& 21.7 & 673.3 & 0.34( 1)\\ 27$_{12,15}$--26$_{12,14}$ & 627699.0(1.5)& $-$0.23& 21.7 & 673.3 & 0.34( 1)\\ 27$_{10,17}$--26$_{10,16}$ & 633168.0(1.5)& $-$0.26& 23.3 & 589.6 & 0.45( 2)\\ 27$_{10,18}$--26$_{10,17}$ & 633168.0(1.5)& $-$0.26& 23.3 & 589.6 & 0.45( 2)\\ 27$_{~~4,24}$--26$_{~~4,23}$ &634776.0(1.5)& $-$2.96& 26.3 & 431.2 & 1.15( 3)\\ 30$_{~~0,30}$--29$_{~~0,29}$ &636346.0(1.5)& 0.01& 29.9 & 450.3 & 1.25( 4)\\ \hline\\[-2ex] \end{tabular} \tablefoot {The first column lists the quantum numbers of the transitions. $\rm o-c$ corresponds to observed minus calculated frequencies. $S$ is the line strength and $E_{\rm{l}}$ is the energy of the lower level of the transition. $I_{\varv}=\int{T_A{\rm d}\varv}$ is the integrated intensity. Values in parentheses are uncertainies in units of the last digits.} \end{table}