\begin{table}%t3
\caption{\label{t:detectetocho-a}Transitions of the \textit{anti}-conformer of ethyl formate detected toward Sgr~B2(N) with the IRAM 30~m telescope.}
\small%\centerline
 {
\begin{tabular}{rlrrrrrcrrrrl}
 \hline\hline
 \multicolumn{1}{c}{$N^a$} & \multicolumn{1}{c}{\hspace*{-1ex} Transition} & \multicolumn{1}{c}{\hspace*{-2ex} Frequency} & \multicolumn{1}{c}{\hspace*{-3ex} Unc.$^b$} & \multicolumn{1}{c}{\hspace*{-1ex} $E_{\rm l}$$^c$} & \multicolumn{1}{c}{\hspace*{-1ex} $S\mu^2$} & \multicolumn{1}{c}{\hspace*{-2ex} $\sigma^d$} & \multicolumn{1}{c}{$F^e$} & \multicolumn{1}{c}{$\tau^f$} & \multicolumn{1}{c}{$I_{{\rm obs}}$$^g$} & \multicolumn{1}{c}{\hspace*{-1ex} $I_{{\rm mod}}$$^g$} & \multicolumn{1}{c}{\hspace*{-1ex} $I_{{\rm all}}$$^g$} & \multicolumn{1}{c}{Comments} \\ 
  & & \multicolumn{1}{c}{\hspace*{-2ex} \scriptsize (MHz)} & \multicolumn{1}{c}{\hspace*{-3ex} \scriptsize (kHz)} & \multicolumn{1}{c}{\hspace*{-1ex} \scriptsize (K)} & \multicolumn{1}{c}{\hspace*{-1ex} \scriptsize (D$^2$)} & \multicolumn{1}{c}{\hspace*{-2ex} \scriptsize (mK)} & & & \multicolumn{1}{c}{\scriptsize (K~km~s$^{-1}$)} & \multicolumn{2}{c}{\hspace*{-1ex} \scriptsize (K~km~s$^{-1}$)} & \\ 
 \multicolumn{1}{c}{(1)} & \multicolumn{1}{c}{\hspace*{-1ex} (2)} & \multicolumn{1}{c}{\hspace*{-2ex} (3)} & \multicolumn{1}{c}{\hspace*{-3ex} (4)} & \multicolumn{1}{c}{\hspace*{-1ex} (5)} & \multicolumn{1}{c}{\hspace*{-1ex} (6)} & \multicolumn{1}{c}{\hspace*{-2ex} (7)} & \multicolumn{1}{c}{(8)} & \multicolumn{1}{c}{(9)} & \multicolumn{1}{c}{(10)} & \multicolumn{1}{c}{(11)} & \multicolumn{1}{c}{\hspace*{-1ex} (12)} & \multicolumn{1}{c}{\hspace*{-1ex} (13)} \\ 
 \hline
   1 & \hspace*{-1ex} 15$_{ 2,14}$--14$_{ 2,13}$ & \hspace*{-2ex}   81~779.567 & \hspace*{-3ex}    4 & \hspace*{-1ex}   30 & \hspace*{-1ex}          51 & \hspace*{-2ex}    13 &    1 & 0.05 &        0.52(06) & \hspace*{-2ex}        0.32 & \hspace*{-2ex}        0.44 &  blend with $U$-line \\ 
  16 & \hspace*{-1ex} 15$_{ 6,10}$--14$_{ 6, 9}$ & \hspace*{-2ex}   82~351.854 & \hspace*{-3ex}    4 & \hspace*{-1ex}   54 & \hspace*{-1ex}          43 & \hspace*{-2ex}    19 &    2 & 0.07 &        1.02(08) & \hspace*{-2ex}        0.44 & \hspace*{-2ex}        0.55 &  partial blend with C$_2$H$_5$CN, \\ 
 & & & & & & & & & & & &  $\varv_{13}$ = 1/$\varv_{21}$ = 1 and $U$-line \\ 
  17 & \hspace*{-1ex} 15$_{ 6, 9}$--14$_{ 6, 8}$ & \hspace*{-2ex}   82~351.858 & \hspace*{-3ex}    4 & \hspace*{-1ex}   54 & \hspace*{-1ex}          43 & \hspace*{-2ex}    19 &    2 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  26 & \hspace*{-1ex} 15$_{ 2,13}$--14$_{ 2,12}$ & \hspace*{-2ex}   84~081.357 & \hspace*{-3ex}    4 & \hspace*{-1ex}   31 & \hspace*{-1ex}          51 & \hspace*{-2ex}    19 &    3 & 0.05 &        0.53(08) & \hspace*{-2ex}        0.35 & \hspace*{-2ex}        0.42 &  partial blend with CH$_3$CH$_3$CO, $\varv_t$ = 1 \\ 
  28 & \hspace*{-1ex} 16$_{ 0,16}$--15$_{ 0,15}$ & \hspace*{-2ex}   85~065.106 & \hspace*{-3ex}    4 & \hspace*{-1ex}   31 & \hspace*{-1ex}          55 & \hspace*{-2ex}    22 &    4 & 0.06 &        0.73(10) & \hspace*{-2ex}        0.39 & \hspace*{-2ex}        0.57 &  partial blend with c-C$_2$H$_4$O \\ 
  44 & \hspace*{-1ex} 16$_{ 8, 8}$--15$_{ 8, 7}$ & \hspace*{-2ex}   87~810.372 & \hspace*{-3ex}    4 & \hspace*{-1ex}   78 & \hspace*{-1ex}          41 & \hspace*{-2ex}    17 &    5 & 0.05 &        1.28(07) & \hspace*{-2ex}        0.40 & \hspace*{-2ex}        1.22 &  partial blend with CH$_2$(OH)CHO \\ 
 & & & & & & & & & & & &  and C$_2$H$_5$CN \\ 
  45 & \hspace*{-1ex} 16$_{ 8, 9}$--15$_{ 8, 8}$ & \hspace*{-2ex}   87~810.372 & \hspace*{-3ex}    4 & \hspace*{-1ex}   78 & \hspace*{-1ex}          41 & \hspace*{-2ex}    17 &    5 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  46 & \hspace*{-1ex} 16$_{ 7, 9}$--15$_{ 7, 8}$ & \hspace*{-2ex}   87~826.665 & \hspace*{-3ex}    4 & \hspace*{-1ex}   67 & \hspace*{-1ex}          44 & \hspace*{-2ex}    17 &    6 & 0.06 &        0.99(07) & \hspace*{-2ex}        0.48 & \hspace*{-2ex}        0.86 &  partial blend with HNCO, $\varv_5$ = 1 \\ 
  47 & \hspace*{-1ex} 16$_{ 7,10}$--15$_{ 7, 9}$ & \hspace*{-2ex}   87~826.665 & \hspace*{-3ex}    4 & \hspace*{-1ex}   67 & \hspace*{-1ex}          44 & \hspace*{-2ex}    17 &    6 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  53 & \hspace*{-1ex} 16$_{ 3,14}$--15$_{ 3,13}$ & \hspace*{-2ex}   87~993.944 & \hspace*{-3ex}    4 & \hspace*{-1ex}   38 & \hspace*{-1ex}          53 & \hspace*{-2ex}    19 &    7 & 0.05 &        1.01(08) & \hspace*{-2ex}        0.39 & \hspace*{-2ex}        0.64 &  partial blend with CH$_3$CH$_3$CO \\ 
 & & & & & & & & & & & &  and $U$-line \\ 
  54 & \hspace*{-1ex} 16$_{ 4,12}$--15$_{ 4,11}$ & \hspace*{-2ex}   88~001.562 & \hspace*{-3ex}    4 & \hspace*{-1ex}   43 & \hspace*{-1ex}          51 & \hspace*{-2ex}    19 &    8 & 0.05 &        0.66(08) & \hspace*{-2ex}        0.35 & \hspace*{-2ex}        0.62 &  blend with C$_2$H$_5$CN, $\varv_{13}$ = 1/$\varv_{21}$ = 1 \\ 
  73 & \hspace*{-1ex} 17$_{10, 7}$--16$_{10, 6}$ & \hspace*{-2ex}   93~284.077 & \hspace*{-3ex}    4 & \hspace*{-1ex}  108 & \hspace*{-1ex}          38 & \hspace*{-2ex}    22 &    9 & 0.04 &        0.07(09) & \hspace*{-2ex}        0.33 & \hspace*{-2ex}        0.35 &  uncertain baseline \\ 
  74 & \hspace*{-1ex} 17$_{10, 8}$--16$_{10, 7}$ & \hspace*{-2ex}   93~284.077 & \hspace*{-3ex}    4 & \hspace*{-1ex}  108 & \hspace*{-1ex}          38 & \hspace*{-2ex}    22 &    9 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  75 & \hspace*{-1ex} 17$_{ 9, 8}$--16$_{ 9, 7}$ & \hspace*{-2ex}   93~292.297 & \hspace*{-3ex}    4 & \hspace*{-1ex}   94 & \hspace*{-1ex}          42 & \hspace*{-2ex}    22 &   10 & 0.05 &        0.56(09) & \hspace*{-2ex}        0.42 & \hspace*{-2ex}        0.50 &  uncertain baseline \\ 
  76 & \hspace*{-1ex} 17$_{ 9, 9}$--16$_{ 9, 8}$ & \hspace*{-2ex}   93~292.297 & \hspace*{-3ex}    4 & \hspace*{-1ex}   94 & \hspace*{-1ex}          42 & \hspace*{-2ex}    22 &   10 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  77 & \hspace*{-1ex} 17$_{ 8, 9}$--16$_{ 8, 8}$ & \hspace*{-2ex}   93~304.955 & \hspace*{-3ex}    4 & \hspace*{-1ex}   82 & \hspace*{-1ex}          45 & \hspace*{-2ex}    22 &   11 & 0.06 &        0.96(09) & \hspace*{-2ex}        0.51 & \hspace*{-2ex}        0.67 &  partial blend with $U$-line \\ 
  78 & \hspace*{-1ex} 17$_{ 8,10}$--16$_{ 8, 9}$ & \hspace*{-2ex}   93~304.955 & \hspace*{-3ex}    4 & \hspace*{-1ex}   82 & \hspace*{-1ex}          45 & \hspace*{-2ex}    22 &   11 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  79 & \hspace*{-1ex} 17$_{ 7,11}$--16$_{ 7,10}$ & \hspace*{-2ex}   93~324.728 & \hspace*{-3ex}    4 & \hspace*{-1ex}   71 & \hspace*{-1ex}          48 & \hspace*{-2ex}    22 &   12 & 0.07 &        1.32(09) & \hspace*{-2ex}        0.60 & \hspace*{-2ex}        0.74 &  partial blend with $U$-lines \\ 
  80 & \hspace*{-1ex} 17$_{ 7,10}$--16$_{ 7, 9}$ & \hspace*{-2ex}   93~324.728 & \hspace*{-3ex}    4 & \hspace*{-1ex}   71 & \hspace*{-1ex}          48 & \hspace*{-2ex}    22 &   12 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  81 & \hspace*{-1ex} 17$_{ 6,12}$--16$_{ 6,11}$ & \hspace*{-2ex}   93~356.821 & \hspace*{-3ex}    4 & \hspace*{-1ex}   62 & \hspace*{-1ex}          51 & \hspace*{-2ex}    22 &   13 & 0.08 &        1.68(10) & \hspace*{-2ex}        0.70 & \hspace*{-2ex}        1.24 &  blend with CH$_3$CH$_3$CO and $U$-line? \\ 
  82 & \hspace*{-1ex} 17$_{ 6,11}$--16$_{ 6,10}$ & \hspace*{-2ex}   93~356.838 & \hspace*{-3ex}    4 & \hspace*{-1ex}   62 & \hspace*{-1ex}          51 & \hspace*{-2ex}    22 &   13 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  83 & \hspace*{-1ex} 17$_{ 5,13}$--16$_{ 5,12}$ & \hspace*{-2ex}   93~412.160 & \hspace*{-3ex}    4 & \hspace*{-1ex}   54 & \hspace*{-1ex}          53 & \hspace*{-2ex}    22 &   14 & 0.08 &        1.12(10) & \hspace*{-2ex}        0.79 & \hspace*{-2ex}        0.85 &  partial blend with $U$-line? \\ 
  84 & \hspace*{-1ex} 17$_{ 5,12}$--16$_{ 5,11}$ & \hspace*{-2ex}   93~413.168 & \hspace*{-3ex}    4 & \hspace*{-1ex}   54 & \hspace*{-1ex}          53 & \hspace*{-2ex}    22 &   14 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  86 & \hspace*{-1ex} 17$_{ 4,14}$--16$_{ 4,13}$ & \hspace*{-2ex}   93~504.972 & \hspace*{-3ex}    4 & \hspace*{-1ex}   47 & \hspace*{-1ex}          55 & \hspace*{-2ex}    24 &   15 & 0.05 &        1.47(10) & \hspace*{-2ex}        0.44 & \hspace*{-2ex}        0.87 &  blend with CH$_3$$^{18}$OH \\ 
  87 & \hspace*{-1ex} 17$_{ 4,13}$--16$_{ 4,12}$ & \hspace*{-2ex}   93~539.303 & \hspace*{-3ex}    4 & \hspace*{-1ex}   47 & \hspace*{-1ex}          55 & \hspace*{-2ex}    24 &   16 & 0.05 &        0.84(10) & \hspace*{-2ex}        0.44 & \hspace*{-2ex}        0.45 & no blend \\ 
  94 & \hspace*{-1ex} 18$_{15, 3}$--17$_{15, 2}$ & \hspace*{-2ex}   98~760.931 & \hspace*{-3ex}    5 & \hspace*{-1ex}  202 & \hspace*{-1ex}          19 & \hspace*{-2ex}    18 &   17 & 0.04 &        0.87(09) & \hspace*{-2ex}        0.68 & \hspace*{-2ex}        0.78 &  blend with $U$-line \\ 
  95 & \hspace*{-1ex} 18$_{15, 4}$--17$_{15, 3}$ & \hspace*{-2ex}   98~760.931 & \hspace*{-3ex}    5 & \hspace*{-1ex}  202 & \hspace*{-1ex}          19 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  96 & \hspace*{-1ex} 18$_{14, 4}$--17$_{14, 3}$ & \hspace*{-2ex}   98~761.079 & \hspace*{-3ex}    5 & \hspace*{-1ex}  181 & \hspace*{-1ex}          24 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  97 & \hspace*{-1ex} 18$_{14, 5}$--17$_{14, 4}$ & \hspace*{-2ex}   98~761.079 & \hspace*{-3ex}    5 & \hspace*{-1ex}  181 & \hspace*{-1ex}          24 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  98 & \hspace*{-1ex} 18$_{16, 2}$--17$_{16, 1}$ & \hspace*{-2ex}   98~761.555 & \hspace*{-3ex}    5 & \hspace*{-1ex}  224 & \hspace*{-1ex}          13 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
  99 & \hspace*{-1ex} 18$_{16, 3}$--17$_{16, 2}$ & \hspace*{-2ex}   98~761.555 & \hspace*{-3ex}    5 & \hspace*{-1ex}  224 & \hspace*{-1ex}          13 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
 100 & \hspace*{-1ex} 18$_{13, 5}$--17$_{13, 4}$ & \hspace*{-2ex}   98~762.218 & \hspace*{-3ex}    5 & \hspace*{-1ex}  162 & \hspace*{-1ex}          30 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
 101 & \hspace*{-1ex} 18$_{13, 6}$--17$_{13, 5}$ & \hspace*{-2ex}   98~762.218 & \hspace*{-3ex}    5 & \hspace*{-1ex}  162 & \hspace*{-1ex}          30 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
 102 & \hspace*{-1ex} 18$_{17, 1}$--17$_{17, 0}$ & \hspace*{-2ex}   98~762.790 & \hspace*{-3ex}    5 & \hspace*{-1ex}  248 & \hspace*{-1ex}           7 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
 103 & \hspace*{-1ex} 18$_{17, 2}$--17$_{17, 1}$ & \hspace*{-2ex}   98~762.790 & \hspace*{-3ex}    5 & \hspace*{-1ex}  248 & \hspace*{-1ex}           7 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
 104 & \hspace*{-1ex} 18$_{12, 6}$--17$_{12, 5}$ & \hspace*{-2ex}   98~764.650 & \hspace*{-3ex}    5 & \hspace*{-1ex}  144 & \hspace*{-1ex}          34 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
 105 & \hspace*{-1ex} 18$_{12, 7}$--17$_{12, 6}$ & \hspace*{-2ex}   98~764.650 & \hspace*{-3ex}    5 & \hspace*{-1ex}  144 & \hspace*{-1ex}          34 & \hspace*{-2ex}    18 &   17 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
 118 & \hspace*{-1ex} 18$_{ 5,14}$--17$_{ 5,13}$ & \hspace*{-2ex}   98~928.453 & \hspace*{-3ex}    4 & \hspace*{-1ex}   58 & \hspace*{-1ex}          57 & \hspace*{-2ex}    18 &   18 & 0.07 &        2.37(09) & \hspace*{-2ex}        0.96 & \hspace*{-2ex}        2.23 &  blend with C$_2$H$_5$CN, $\varv_{13}$ = 1/$\varv_{21}$ = 1 \\ 
 119 & \hspace*{-1ex} 18$_{ 5,13}$--17$_{ 5,12}$ & \hspace*{-2ex}   98~930.153 & \hspace*{-3ex}    4 & \hspace*{-1ex}   58 & \hspace*{-1ex}          57 & \hspace*{-2ex}    18 &   18 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
 160 & \hspace*{-1ex} 20$_{ 1,20}$--19$_{ 1,19}$ & \hspace*{-2ex}  105~234.713 & \hspace*{-3ex}    5 & \hspace*{-1ex}   49 & \hspace*{-1ex}          68 & \hspace*{-2ex}    28 &   19 & 0.07 &        1.66(11) & \hspace*{-2ex}        0.76 & \hspace*{-2ex}        1.27 &  blend with C$_2$H$_5$OH and CH$_3$OCHO \\ 
 161 & \hspace*{-1ex} 19$_{ 1,18}$--18$_{ 1,17}$ & \hspace*{-2ex}  105~272.047 & \hspace*{-3ex}    5 & \hspace*{-1ex}   47 & \hspace*{-1ex}          65 & \hspace*{-2ex}    28 &   20 & 0.07 &        2.07(11) & \hspace*{-2ex}        0.73 & \hspace*{-2ex}        0.81 &  blend with $U$-lines \\ 
 162 & \hspace*{-1ex} 19$_{ 3,16}$--18$_{ 3,15}$ & \hspace*{-2ex}  105~447.141 & \hspace*{-3ex}    5 & \hspace*{-1ex}   52 & \hspace*{-1ex}          64 & \hspace*{-2ex}    37 &   21 & 0.06 &        1.07(15) & \hspace*{-2ex}        0.69 & \hspace*{-2ex}        1.07 & no blend \\ 
 165 & \hspace*{-1ex} 20$_{ 2,19}$--19$_{ 2,18}$ & \hspace*{-2ex}  108~552.378 & \hspace*{-3ex}  100 & \hspace*{-1ex}   53 & \hspace*{-1ex}          68 & \hspace*{-2ex}    20 &   22 & 0.07 &        2.05(08) & \hspace*{-2ex}        0.79 & \hspace*{-2ex}        1.24 &  partial blend with C$_2$H$_3$CN, $\varv_{15}$ = 1 \\ 
 & & & & & & & & & & & &  and $U$-lines \\ 
 233 & \hspace*{-1ex} 21$_{ 6,16}$--20$_{ 6,15}$ & \hspace*{-2ex}  115~395.797 & \hspace*{-3ex}    5 & \hspace*{-1ex}   81 & \hspace*{-1ex}          66 & \hspace*{-2ex}    60 &   23 & 0.11 &        2.94(23) & \hspace*{-2ex}        1.37 & \hspace*{-2ex}        1.37 &  partial blend with $U$-line \\ 
 234 & \hspace*{-1ex} 21$_{ 6,15}$--20$_{ 6,14}$ & \hspace*{-2ex}  115~395.986 & \hspace*{-3ex}    5 & \hspace*{-1ex}   81 & \hspace*{-1ex}          66 & \hspace*{-2ex}    60 &   23 & -- & -- & \hspace*{-2ex} -- & \hspace*{-2ex} -- & -- \\ 
 238 & \hspace*{-1ex} 22$_{ 1,22}$--21$_{ 1,21}$ & \hspace*{-2ex}  115~595.764 & \hspace*{-3ex}    5 & \hspace*{-1ex}   59 & \hspace*{-1ex}          75 & \hspace*{-2ex}    79 &   24 & 0.08 &       --0.05(30) & \hspace*{-2ex}        0.99 & \hspace*{-2ex}        2.22 &  blend with CH$_3$CH$_3$CO, $\varv_t$ = 1,  \\ 
 & & & & & & & & & & & & uncertain baseline \\ 
 \hline
 \end{tabular}}
\medskip
Notes: $^a$ Numbering of the observed transitions associated with a modeled line stronger than 20~mK (see Table~\ref{t:etocho-a}). 
$^b$~Frequency uncertainty. 
$^c$~Lower energy level in temperature units ($E_{\rm l}/k_{\rm B}$).
$^d$~Calculated rms noise level in $T_{{\rm mb}}$~scale.
$^e$~Numbering of the observed features.
$^f$~Peak opacity of the modeled feature.
$^g$~Integrated intensity in $T_{{\rm mb}}$ scale for the observed spectrum (Col.~10), the ethyl formate model (Col.~11), and the model including all molecules (Col.~12). The uncertainty in Col.~10 is given in parentheses in units of the last digit.
\end{table}