\begin{table}%t3 \caption{\label{t:dcop-data}Measured hyperfine splitting $\Delta ^a$ (kHz) and residual o$-$c of \dcop, DNC, and HN\thc\ relative to a selected hyperfine component.} %\centerline { \begin{tabular}{lr@{}lr@{}l} \hline \hline Transition & \multicolumn{1}{c}{Splitting} & \multicolumn{1}{l}{Residual$^b$} \\ \hline \multicolumn{5}{l}{\dcop: $F = 2{-}1$ at 72~039.306~(3) MHz} \\ \hline $1{-}1$ & +47.58~(144)& 1.20 \\ $0{-}1$ & $-$64.64~(144)& 0.80 \\ \hline \multicolumn{5}{l}{DNC: $I,F = 2{,}1{-}2{,}2 / 2{,}1{-}0{,}0$ at 76305.512~(3) MHz} \\ \hline $1{,}1{-}1{,}1$ & 115.30~(100) & $-$0.18 \\ $2{,}3{-}2{,}2$ & 175.44~(100) & $-$0.72 \\ $1{,}2{-}1{,}1$ & 204.63~(100) & 1.38 \\ $2{,}2{-}2{,}2$ & 277.57~(100) & $-$0.82 \\ $0{,}1{-}0{,}0$ & & \\ $0{,}1{-}2{,}2$ & & \\ $1{,}0{-}1{,}1$ & 325.50~(250) & 1.60 \\ \hline \multicolumn{5}{l}{HN\thc: $F_1,F_2,F = 0{,}1{,}1{-}1{,}2{,}2$ at 87~090.675~(3) MHz} \\ \hline $2{,}2{,}2{-}1{,}1{,}1$ & 115.5~(50) & $-$7.3 \\ $2{,}2{,}2{-}1{,}2{,}2$ & & & & \\ $2{,}2{,}1{-}1{,}1{,}0$ & & & & \\ $2{,}2{,}1{-}1{,}2{,}1$ & & & & \\ $2{,}3{,}3{-}1{,}2{,}2$ & 158.5~(50) & 5.0 \\ $2{,}3{,}2{-}1{,}1{,}1$ & & & & \\ $2{,}3{,}2{-}1{,}2{,}1$ & & & & \\ $1{,}1{,}1{-}1{,}1{,}1$ & 210.7~(50) & 1.5 \\ $1{,}2{,}2{-}1{,}2{,}1$ & & & & \\ $1{,}2{,}2{-}1{,}2{,}2$ & & & & \\ \hline \end{tabular}} \medskip \par If no numbers are given for the value of a measured splitting and its residual, the hyperfine component overlaps with the previous component. The values of the splitting and the residual refer to the respective intensity weighted averages.\\ $^a$ Numbers in parentheses are one standard deviation in units of the least significant figures.\\ $^b$ Residuals for DCO$^+$ refer to fit with $C_I$ kept fixed. The residuals are zero if $C_I$ is released as two pieces of information are then used to derive two parameters. \end{table}