All Figures

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{images/3842fg01.eps}\end{figure}$ Figure 1: Grey-scale representation of the photometric error as a function of the $K_{\rm s}$ magnitude for the 2MASS observations in the field $(l,b)=(50\hbox {$^\circ $ },0\hbox {$^\circ $ })$ . The solid line shows our best fit using Eq. (3).
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{images/3842fg02.eps}\end{figure}$ Figure 2: Simulated colour-distance distribution towards $l=330\hbox {$^\circ $ }$ $b={1.5\hbox {$^\circ $ }}$ . Crosses are giants, triangles are dwarf stars and the diamonds denote rejected giants (Sect. 4.3). The group of stars in the lower left corner is dominated by dwarfs and sub-giants. There is a relation between colour and distance for the giants, first dominated by K&M stars, then, at larger distances by RGB/AGB stars.
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In the text

$\begin{figure} \par\includegraphics[width=8.85cm,clip]{images/3842fg03.eps}\end{figure}$ Figure 3: Dwarf star removal for the field (l,b) = (330, 1.5). The triangles are dwarf stars, the diamonds are sub-giants and the crosses are regular giants. The lines running from top to bottom near $J{-}K_{\rm s}=0.9$ are the cut-off for dwarf stars before (dashed) and after (solid) the first determination of the extinction. The dotted line at $m_{K{\rm s}}=12$ shows our faint magnitude cutoff.
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{images/3842fg04.eps}\par\includegraphics[width=6.8cm,clip]{images/3842fg05.eps}\end{figure}$ Figure 4: Initial and final results of the extinction calculation for the field (l,b)=(345,0). Top: $A_{K{\rm s}}$ as a function of distance. Each diamond represents a bin from the initial calculation, the asterisks represent the bins in the final result and the error bars represent the mean absolute deviation of the extinction in the bin. Bottom: $J{-}K_{\rm s}$ colour distribution of 2MASS and adjusted Galactic model. The red solid line represents the 2MASS data, the bold solid line represents the final result and the broken line shows our initial calculation.
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In the text

$\begin{figure} \par\includegraphics[width=5.9cm,clip]{images/3842fg06.eps}\inclu... ...pace*{2.5mm} \includegraphics[width=5.7cm,clip]{images/3842fg11.eps}\end{figure}$ Figure 5: Results for the three fields at galactic coordinates (l,b) = (57,0), (330,1.5) and (5,0). Top: $A_{K{\rm s}}$ vs. distance. Each asterisk represents a bin from our method, and the error bars are the mean absolute deviation from the median extinction in the bin. Bottom: corresponding $J{-}K_{\rm s}$ histogram of the model and the observations. The red line represents the 2MASS observations and the black line is the result of our method.
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In the text

$\begin{figure} \par\includegraphics[width=4.1cm,clip]{images/3842fg12.eps}\includegraphics[width=4.1cm,clip]{images/3842fg13.eps}\end{figure}$ Figure 6: Comparison between each pixel of our extinction map and that of Schultheis et al. (1999) (S99), for $\vert l\vert<8\hbox {$^\circ $ }$ , $\vert b\vert<1\hbox {$^\circ $ }$ , and Dutra et al. (2003) (D03), for $\vert l\vert\le 5.0\hbox {$^\circ $ }$ , $\vert b\vert\le 5.0\hbox {$^\circ $ }$ . Left: $A_{K{\rm s}}$ of our map vs. that of S99. Right: $A_{K{\rm s}}$ of our map vs. that of D03. For both figures, the straight line represents the identity function.
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In the text

$\begin{figure} \par\includegraphics[width=14.3cm,clip]{images/3842fg14.eps}\end{figure}$ Figure 7: Top: total extinction integrated along the line of sight. Bottom: CO velocity integrated spatial map by Dame et al. (2001). The units of the two maps are different; they are put here to compare their respective interpretation of the large scale structure of the Galaxy. The coordinates are expressed in degrees (l,b).
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In the text

$\begin{figure} \par\includegraphics[width=17.25cm,clip]{images/3842fg15.eps}\end{figure}$ Figure 8: The local extinction at 1 kpc intervals from the sun. The uppermost image is at 1 kpc, the bottom one is at 8 kpc. The x axis is in Galactic longitude, the y axis in Galactic latitude. The solid line indicates the mean position of the plane, as given by the stellar warp formula in the Galactic model. Different structures are identified in the text (Sect. 5.4.1).
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In the text

$\begin{figure} \par\includegraphics[width=16.7cm,clip]{images/3842fg16.eps}\end{figure}$ Figure 9: Location of absorbing dust in the Galactic Plane ( $\vert b\vert \le 0.25$ ). The Galactic centre, assumed to be at 8.5 kpc from the Sun, is marked with an "X''; the Sun is located in the middle on the left side of the plot. The dotted lines are placed every 5 kpc from the Sun. Ticks on the border indicate Galactic longitude.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{images/3842fg17.eps}\end{figure}$ Figure 10: Variation of the density of absorbing matter as a function of distance from the Galactic plane.
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In the text

$\begin{figure} \par\hspace*{-2mm} \includegraphics[width=8.15cm,clip]{images/3842fg18.eps} \includegraphics[width=8.25cm,clip]{images/3842fg19.eps} \end{figure}$ Figure 11: Local extinction at 8 kpc from the Sun for positive longitudes ( top) and negative longitudes ( bottom). The stellar warp as modelled in the Galactic model is shown as a dashed line; the solid line shows the best fit to our extinction data (Sect. 5.5.2). The colour scale is the same as in Fig. 8.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{images/3842fg20.eps}\end{figure}$ Figure 12: Straight line fit that minimises the mean absolute deviation of the points of highest density along the Galactic bar.
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In the text

$\begin{figure} \par\mbox{\includegraphics[width=5.35cm,clip]{images/3842fg21.eps... ...g25.eps} \includegraphics[width=5.6cm,clip]{images/3842fg26.eps} } \end{figure}$ Figure 13: The extinction, along the line of sight, in six different fields. For each field, we have compared our results (asterisks) with the results of Neckel et al. (1980) (triangles), Drimmel et al. (2003) (solid line) and López-Corredoira et al. (2002) (diamonds), where available.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{images/3842fg27.eps}\end{figure}$ Figure 14: Influence of the assumed disc density law near the Galactic centre. Median extinction difference, at different heliocentric distances and at $\vert l\vert \le 10\hbox {$^\circ $ }$ and $\vert b\vert \le 2.5\hbox {$^\circ $ }$ , between two determinations of the extinction using models with different values for the disc hole scale length ( $R_{\rm h}$ in Eq. (1)). The error bars represent the mean absolute deviation from the median. The difference is calculated per pixel, at each heliocentric distance. A positive difference shows that the model with the larger $R_{\rm h}$ predicts a larger value for the extinction.
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In the text

$\begin{figure} \par\mbox{\includegraphics[width=5.9cm,clip]{images/3842fg28.eps}... ...32.eps} \includegraphics[width=5.9cm,clip]{images/3842fg33.eps} } \end{figure}$ Figure 15: Influence of the assumed disc scale length. Simulated observations are computed with a scale length of 2.51 kpc (first column), 2. kpc (2nd col.), and 3. kpc (3rd col.) while the scale length of the model used for computing the extinction is assumed to be 2.51 kpc in each case. Top: the distribution of extinction along the line of sight at $(l,b) = (10{\hbox {$^\circ $ }},0{\hbox {$^\circ $ }})$ . The solid line represents the known extinction law of the simulated observations and the asterisks are the results of our method. In each case the scale length used in the simulated observations is included in the graph. Bottom: the corresponding $J{-}K_{\rm s}$ histograms with the extinction applied. It is noticeable that the fact that the model does not reproduce the number density of stars in the observations does not influence the determined extinction.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{images/3842fg01.eps}\end{figure}$	Figure 1: Grey-scale representation of the photometric error as a function of the $K_{\rm s}$ magnitude for the 2MASS observations in the field $(l,b)=(50\hbox {$^\circ $ },0\hbox {$^\circ $ })$ . The solid line shows our best fit using Eq. (3).
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$\begin{figure} \par\includegraphics[width=14.3cm,clip]{images/3842fg14.eps}\end{figure}$	Figure 7: Top: total extinction integrated along the line of sight. Bottom: CO velocity integrated spatial map by Dame et al. (2001). The units of the two maps are different; they are put here to compare their respective interpretation of the large scale structure of the Galaxy. The coordinates are expressed in degrees (l,b).
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$\begin{figure} \par\includegraphics[width=17.25cm,clip]{images/3842fg15.eps}\end{figure}$	Figure 8: The local extinction at 1 kpc intervals from the sun. The uppermost image is at 1 kpc, the bottom one is at 8 kpc. The x axis is in Galactic longitude, the y axis in Galactic latitude. The solid line indicates the mean position of the plane, as given by the stellar warp formula in the Galactic model. Different structures are identified in the text (Sect. 5.4.1).
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$\begin{figure} \par\includegraphics[width=16.7cm,clip]{images/3842fg16.eps}\end{figure}$	Figure 9: Location of absorbing dust in the Galactic Plane ( $\vert b\vert \le 0.25$ ). The Galactic centre, assumed to be at 8.5 kpc from the Sun, is marked with an "X''; the Sun is located in the middle on the left side of the plot. The dotted lines are placed every 5 kpc from the Sun. Ticks on the border indicate Galactic longitude.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{images/3842fg17.eps}\end{figure}$	Figure 10: Variation of the density of absorbing matter as a function of distance from the Galactic plane.
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$\begin{figure} \par\hspace*{-2mm} \includegraphics[width=8.15cm,clip]{images/3842fg18.eps} \includegraphics[width=8.25cm,clip]{images/3842fg19.eps} \end{figure}$	Figure 11: Local extinction at 8 kpc from the Sun for positive longitudes ( top) and negative longitudes ( bottom). The stellar warp as modelled in the Galactic model is shown as a dashed line; the solid line shows the best fit to our extinction data (Sect. 5.5.2). The colour scale is the same as in Fig. 8.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{images/3842fg20.eps}\end{figure}$	Figure 12: Straight line fit that minimises the mean absolute deviation of the points of highest density along the Galactic bar.
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$\begin{figure} \par\mbox{\includegraphics[width=5.35cm,clip]{images/3842fg21.eps... ...g25.eps} \includegraphics[width=5.6cm,clip]{images/3842fg26.eps} } \end{figure}$	Figure 13: The extinction, along the line of sight, in six different fields. For each field, we have compared our results (asterisks) with the results of Neckel et al. (1980) (triangles), Drimmel et al. (2003) (solid line) and López-Corredoira et al. (2002) (diamonds), where available.
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