All Figures

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{2890fig1.eps} \end{figure}$ Figure 1: Example of a SWAN field: SBSF 18. The circles are the extended objects detected by SExtractor (SExtractor stellarity index ${\rm SSI} < 0.9$ ), while the squares are point sources ( ${\rm SSI} \geq 0.9$ ). A ghost of the bright guide star is marked with a cross.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{2890fig2.ps} \end{figure}$ Figure 2: Isoplanatic angle scaling. The Strehl ratios of point sources in the two calibration fields and 7 SWAN fields (SBSF 14, SBSF 15, SBSF 18, SBSF 24, SBSF 27, SBSF 28, SBSF 41) are plotted against their radial distance $\alpha$ from the AO guide star (in units of the corresponding isoplanatic angle). The black solid line is the theoretical curve used for fitting.
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In the text

$\begin{figure} \par\includegraphics[width=11.6cm,clip]{2890fig3.ps} \end{figure}$ Figure 3: Upper panels: FWHM fits to the kernel. The radial ( left panel) and tangential ( right panel) FWHMs of the kernel to be convolved with the on-axis PSF to reproduce the observed PSF for the point sources in the calibration fields (diamonds) and in the seven SWAN fields of Fig. 2 (pluses), along with the best fitting second order polynomial. Lower panels: the total FWHMs of the observed point sources (radial at left, tangential at right) as a function of radial distance $\alpha$ from the guide star in units of the corresponding isoplanatic angle $\theta _0$ , compared to the best fitting model for the kernel convolved with the guide star's FWHM.
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In the text

$\begin{figure} \par\includegraphics[width=6.5cm,clip]{2890fig4.ps} \end{figure}$ Figure 4: Residuals from the PSF fitting with the elliptical kernel for the point sources in the two calibration fields, NGC 6752 (triangles) and NGC 6809 (squares), and in the 7 SWAN fields of Fig. 2 (stars). The residuals plotted are defined in Eq. (3).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{2890fig5.ps} \end{figure}$ Figure 5: Comparison between the true and model PSFs for a point source in NGC 6752. The left panel shows the original star, the central panel the model for the corresponding position on the detector, and the right panel the residuals after subtracting the two. The star is located at 26.8 $^{\prime \prime }$ from the AO guide star.
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In the text

$\begin{figure} \par\mbox{\includegraphics[width=8cm,clip]{2890fig6.ps}\hspace{1.15cm} \includegraphics[width=8cm,clip]{2890fig7.ps} } \end{figure}$ Figure 6: The left panels show the rms of the magnitude, Sérsic index and effective radius obtained from the GALFIT fits of the simulated profiles with Sérsic index n = 1 as a function of the input magnitude. For each point, 100 galaxies with 10 different PSF were used (see text for details). The solid lines are the rms obtained using the model PSF as an input for GALFIT, while the dashed ones are obtained with the original NACO PSF. The right panels show the results obtained for simulated profiles with Sérsic index n = 4. In both cases it is clear that the parameters can be reliably recovered up to $K_{\rm s} \sim 20$ .
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{2890fig8.ps} \end{figure}$ Figure 7: Disk/elliptical separation using GALFIT measurement of Sérsic index for simulated profiles with $K_{\rm s} = 20$ . The upper panel shows the input distributions of Sérsic index, while the central panel shows the results using the true NACO PSF used to build the profile as an input for GALFIT, and the lower panel what is obtained with the model PSF. The discriminating value for the Sérsic index n = 2 (see text) is shown as a gray line.
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In the text

$\begin{figure} \par\includegraphics[width=7.1cm,clip]{2890fig9.ps} \end{figure}$ Figure 8: The fraction of ellipticals recovered with n>2 (left panel) and the fraction of disks recovered with a Sérsic index n < 2 (right panel) as a function of the input magnitude. The dashed lines show the results obtained using the true NACO PSF, while the solid lines the ones obtained with the model PSF.
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In the text

$\begin{figure} \par\includegraphics[width=14.3cm,clip]{2890fig10.eps} \end{figure}$ Figure 9: Examples of single and multiple component fits by GALFIT of SWAN galaxies using the model PSF. In all images North is up and East is left. The distance of the galaxy from the guide star is shown in the upper right corner of each panel. For both galaxies, the $K_{\rm s}$ magnitude and the source identifier according to Baker et al. (2003) are reported. Upper panel: single component Sérsic fit ( $K_{\rm s} =19.2$ ; $R_{\rm e} = 0.4\hbox {$^{\prime \prime }$ }$ ; n = 0.6; b/a = 0.6; PA = 75). The left image is the original galaxy, the GALFIT best fitting profile is in the middle, and the residuals of the subtraction are on the right. Lower panel: comparison of the residuals between a single component fit (in the middle) and a two component fit (on the right), while the original galaxy is shown on the left. The final best fit was obtained with a disk component ( $K_{\rm s} = 19.6$ ; $R_{\rm e} = 0.4\hbox {$^{\prime \prime }$ }$ ; n = 1.0; b/a = 0.7; PA = 76) and a point source ( $K_{\rm s} = 21.4$ ) in the center.
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In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{2890fig11.ps} \end{figure}$ Figure 10: Distribution of effective radii $R_{\rm e}$ for the 55 sources detected down to $K_{\rm s} = 20$ in the five SWAN fields observed with NACO (black hatched histograms), and for the 92 sources down to $K_{\rm s} = 20$ observed in in larger fields centered on the same stars with SOFI (gray shaded histograms). The distribution is not corrected for completeness. For galaxies with more than one component, only the parameters of the larger scale (i.e., non-nuclear) one are used.
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In the text

$\begin{figure} \par\includegraphics[width=7.55cm,clip]{2890fig12.ps} \end{figure}$ Figure 11: The difference $\Delta \phi$ between the radial vector from the guide star to the source at offset ( $\Delta x, \Delta y$ ) and the source's own major axis position angle $\phi$ as measured with SExtractor (left panel) with no PSF correction and with GALFIT (right panel) using the model PSF. In each panel the distribution for objects with angular distance from the guide star < $17\hbox {$^{\prime \prime }$ }$ and $\geq$ $17\hbox {$^{\prime \prime }$ }$ are shown (solid lines) as well as the total distribution of all sources (dashed line). Error bars are $\sqrt {N}$ for N the number of objects in each bin.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{2890fig1.eps} \end{figure}$	Figure 1: Example of a SWAN field: SBSF 18. The circles are the extended objects detected by SExtractor (SExtractor stellarity index ${\rm SSI} < 0.9$ ), while the squares are point sources ( ${\rm SSI} \geq 0.9$ ). A ghost of the bright guide star is marked with a cross.
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$\begin{figure} \par\includegraphics[width=7.8cm,clip]{2890fig2.ps} \end{figure}$	Figure 2: Isoplanatic angle scaling. The Strehl ratios of point sources in the two calibration fields and 7 SWAN fields (SBSF 14, SBSF 15, SBSF 18, SBSF 24, SBSF 27, SBSF 28, SBSF 41) are plotted against their radial distance $\alpha$ from the AO guide star (in units of the corresponding isoplanatic angle). The black solid line is the theoretical curve used for fitting.
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$\begin{figure} \par\includegraphics[width=6.5cm,clip]{2890fig4.ps} \end{figure}$	Figure 4: Residuals from the PSF fitting with the elliptical kernel for the point sources in the two calibration fields, NGC 6752 (triangles) and NGC 6809 (squares), and in the 7 SWAN fields of Fig. 2 (stars). The residuals plotted are defined in Eq. (3).
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{2890fig5.ps} \end{figure}$	Figure 5: Comparison between the true and model PSFs for a point source in NGC 6752. The left panel shows the original star, the central panel the model for the corresponding position on the detector, and the right panel the residuals after subtracting the two. The star is located at 26.8 $^{\prime \prime }$ from the AO guide star.
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$\begin{figure} \par\includegraphics[width=7.1cm,clip]{2890fig9.ps} \end{figure}$	Figure 8: The fraction of ellipticals recovered with n>2 (left panel) and the fraction of disks recovered with a Sérsic index n < 2 (right panel) as a function of the input magnitude. The dashed lines show the results obtained using the true NACO PSF, while the solid lines the ones obtained with the model PSF.
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