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$\begin{figure} \par\includegraphics[angle=270,width=9cm,clip]{9203f2.eps}\end{figure}$ Figure 2: Population diagram of amino acetonitrile in Sgr B2(N). The red points were computed in the optically thin approximation using the integrated intensities of our best-fit model of amino acetonitrile, while the green points were corrected for the opacity. The black points were computed in the optically thin approximation using the integrated intensities of the spectrum observed with the IRAM 30 m telescope. The error bars are $1 \sigma$ uncertainties on $N_{\rm u}/g_{\rm u}$ . Blue arrows pointing downwards mark the transitions blended with transitions from other molecules, while blue arrows pointing upwards indicate that the baseline removed in the observed spectrum is uncertain. The arrow length is arbitrary. The measurement corresponding to feature 43 (at $E_{\rm u}/k_{\rm B}$ = 265 K) is not shown since the integrated intensity measured toward Sgr B2(N) is negative, due to the blend with CN absorption lines.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=9cm,clip]{9203f3.eps}\end{figure}$ Figure 3: Spectrum obtained toward Sgr B2(N) ( bottom) and Sgr B2(M) ( top) with the IRAM 30 m telescope at the frequency of amino acetonitrile (AAN) transition 192 (see caption of Fig. 1 for more details about the color coding). There are too many blended lines in the spectrum of Sgr B2(N) to properly remove the baseline, which is very uncertain and most likely at a lower level than could be computed here. This is the only discrepancy concerning the amino acetonitrile lines in the whole survey. The absorption lines, particularly strong in the spectrum of Sgr B2(M), are velocity components of H¹³CN 2-1.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.9cm,clip]{9203f4.eps}\end{figure}$ Figure 4: Spectra obtained with the Plateau de Bure interferometer (a) to f)) and the 30 m telescope (g) and h)) toward Sgr B2(N) (in black). The dotted lines show the frequency ranges listed in Table 5. The offset position with respect to the reference position of Fig. 5 is given in each panel, along with a label (P1 to P3, see their definition in Table 6). The lines identified in our 30 m survey are labeled in blue. The red spectra show our best-fit model for amino acetonitrile (AAN) while the green spectrum corresponds to the 30 m model including all molecules. The observed lines which have no counterpart in the green spectrum are still unidentified.
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In the text

$\begin{figure} \par\includegraphics[height=18.4cm,angle=-90,clip]{NEWFIG5/9203f5.eps}\end{figure}$ Figure 5: Integrated intensity maps (panels a) to n)) and continuum map (panel o)) obtained toward Sgr B2(N) with the Plateau de Bure interferometer at 82 GHz. Panels a) to e) show the amino acetonitrile (AAN) features F2 to F6 (see Fig. 4 and Table 3). Panel f) is a reference map integrated on the emission-free frequency range between F2 and F3. Panels g) to n) show the other molecules listed in Table 5. The lowest contour (positive in black solid line and negative in blue dotted line) and the contour step are 2 $\sigma$ for panel f), 3 $\sigma$ for panels a) to e) and panel n), 4 $\sigma$ for panels g) and h), 5 $\sigma$ for panels i) to l), and 6 $\sigma$ for panel m) (with $\sigma$ given in Col. 5 of Table 5). For panel o), the first contours are 5 $\sigma$ and 10 $\sigma$ , and the contour step is 10 $\sigma$ for the other contours (with $\sigma$ = 8.5 mJy/beam). In each panel, the 0, 0 position is $\alpha_{{\rm J2000}} = 17^{{\rm h}}47^{{\rm m}}20\hbox{$.\!\!^{\rm s}$ }00$ , $\delta _{{\rm J2000}} = -28^\circ 22\hbox {$^\prime $ }19.0\hbox {$^{\prime \prime }$ }$ , the three plus symbols mark the positions P1, P2, and P3 (labeled in panel f)), and the filled ellipse in the top right corner shows the clean beam ( HPBW = $3.35\hbox {$^{\prime \prime }$ }$ $\times$ $0.81\hbox {$^{\prime \prime }$ }$ at PA = 9.7 $^\circ$ ). The cross symbols in panel o) are the peak positions of the (ultracompact) H II regions detected by Gaume et al. (1995) at 1.3 cm (K9.69, K1, K2, K3, K5, and K6, from right to left). The spectral integration was done on the frequency ranges given in Table 5. The continuum map was computed on line-free frequency ranges. The maps are not corrected for primary beam attenuation. The amino acetonitrile features emit at the same position as the vibrationally excited state v₄ = 1 of cyanoacetylene. Feature F4 is partially blended with a transition from HCC¹³CN, v₆ = 1.
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In the text

$\begin{figure} \par\includegraphics[width=9cm,clip]{9203f6.eps}\end{figure}$ Figure 6: Spectra obtained with the Australia Telescope Compact Array (a) to j)) and the 30 m telescope (k) and l)) toward Sgr B2(N) (black histogram). The dotted lines show the frequency ranges listed in Table 7. The offset position with respect to the reference position of Fig. 7 is given in each panel. The lines identified in our 30 m survey are labeled in blue. The red spectrum shows our best-fit model for amino acetonitrile (AAN) while the green spectrum corresponds to the 30 m model including all molecules. The observed lines which have no counterpart in the green spectrum are still unidentified. a) and b) show the extended configuration H 214, c) and d) the intermediate configuration H 168, e) and f) the compact configuration H 75, g) and h) the combination of H 214 and H 168, and i) and j) the combination of all three configurations. The spectral coverage is not the same for all configurations because the sky tuning frequency for H 168 and H 75 was not corrected for the observatory velocity variations. The clean beam size ( HPBW) is given in each panel.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=18cm,clip]{9203f7.eps}\end{figure}$ Figure 7: Integrated intensity maps (panels a) to v)) and continuum map (panel w)) obtained toward Sgr B2(N) with the Australia Telescope Compact Array at 3 mm. Panels a) to p) show the amino acetonitrile features F7 to F10 in the different configurations (see Fig. 6). Panels q) to v) show the other molecules listed in Table 7. The lower contour (positive in black solid line and negative in blue dotted line) and the contour step are 3 $\sigma$ for panels a), b), d) to h), j) to m), and o) to q), 4 $\sigma$ for panels r), t), and u), 5 $\sigma$ for panels c), i) and n), and 6 $\sigma$ for panels s) and v) (with $\sigma$ given in Col. 5 of Table 7). For panel w), the first contours are 3 and 6 $\sigma$ , and the contour step is 6 $\sigma$ for the other contours (with $\sigma = 37$ mJy/beam). In each panel, the 0, 0 position is $\alpha_{{\rm J2000}} = 17^{{\rm h}}47^{{\rm m}}20\hbox{$.\!\!^{\rm s}$ }00$ , $\delta _{{\rm J2000}} = -28^\circ 22\hbox {$^\prime $ }19.0\hbox {$^{\prime \prime }$ }$ , the two thick plus symbols mark positions P4 and P5 (labeled in panel a)), and the filled ellipse in the top right corner shows the clean beam. The cross symbols in panel w) are the peak positions of the (ultracompact) H II regions detected by Gaume et al. (1995) at 1.3 cm (K9.69, and K1 to K6, from right to left). The spectral integration was done on the frequency ranges given in Table 7. The maps are not corrected for primary beam attenuation. Panel x) displays the ATCA positions P4 and P5 with thick plus symbols and the PdBI positions P1 to P3 with thin plus symbols, for visual comparison.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{9203f8.eps}\end{figure}$ Figure 8: Continuum image of the Sgr B2 region obtained with the Very Large Array at 9.1 GHz . The lowest contour level is 4 times the rms noise level of 8 mJy beam^-1 and contours double in value until they reach 512 times that level. The dotted circle represents the FWHM of the VLA antennas' primary beam at 9.1 GHz. The image is not corrected for attenuation due to the primary beam's response. Note that it is produced from data taken over only a 1 h period and has limited dynamic range and sensitivity. It is, however, consistent with the higher sensitivity three-pointing-mosaic 4.8 GHz image presented by Mehringer et al. (1995), which has a similar resolution. The synthesized beam is represented in the lower left corner. The upper and lower shaded circles are centered at the Sgr B2(N) and (M) pointing positions of our 30 m telescope spectral line survey, respectively. Their size corresponds to the $25\hbox {$^{\prime \prime }$ }$ FWHM of the 30 m telescope at 100 GHz.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.5cm,clip]{9203f101.ps}\hsp... ...ce*{0.5cm} \includegraphics[angle=270,width=7.3cm,clip]{9203f108.ps}\end{figure}$ Figure 1: Transitions of amino acetonitrile (AAN) detected with the IRAM 30 m telescope. Each panel consists of two plots and is labeled in black in the upper right corner. The lower plot shows in black the spectrum obtained toward Sgr B2(N) in main-beam temperature scale (K), while the upper plot shows the spectrum toward Sgr B2(M). The rest frequency axis is labeled in GHz. The systemic velocities assumed for Sgr B2(N) and (M) are 64 and 62 km s^-1, respectively. The lines identified in the Sgr B2(N) spectrum are labeled in blue. The top red label indicates the AAN transition centered in each plot (numbered like in Col. 1 of Table 3), along with the energy of its lower level in K ( $E_{\rm l}/k_{{\rm B}}$ ). The other AAN lines are labeled in blue only. The bottom red label is the feature number (see Col. 8 of Table 3). The green spectrum shows our LTE model containing all identified molecules, including AAN. The LTE synthetic spectrum of AAN alone is overlaid in red, and its opacity in dashed violet. All observed lines which have no counterpart in the green spectrum are still unidentified in Sgr B2(N).
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.5cm,clip]{9203f109.ps}\hsp... ...e*{0.5cm} \includegraphics[angle=270,width=7.3cm,clip]{9203f116.ps} \end{figure}$ Figure 1: continued.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.5cm,clip]{9203f117.ps}\hsp... ...e*{0.5cm} \includegraphics[angle=270,width=7.3cm,clip]{9203f124.ps} \end{figure}$ Figure 1: continued.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.5cm,clip]{9203f125.ps}\hsp... ...e*{0.5cm} \includegraphics[angle=270,width=7.3cm,clip]{9203f132.ps} \end{figure}$ Figure 1: continued.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.5cm,clip]{9203f133.ps}\hsp... ...e*{0.5cm} \includegraphics[angle=270,width=7.3cm,clip]{9203f140.ps} \end{figure}$ Figure 1: continued.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.5cm,clip]{9203f141.ps} \end{figure}$ Figure 1: continued.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.5cm,clip]{9203f109.ps}\hsp... ...e*{0.5cm} \includegraphics[angle=270,width=7.3cm,clip]{9203f116.ps} \end{figure}$	Figure 1: continued.
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