compare it with the SPHERE astrometry. The results are shown in Fig. \[fig:cpmtest\]. The motion of the [point source]{} between the two epochs reflects the s[tellar proper motion [$\mu_{\mathrm{\alpha}}$=$-$20.159$\pm$0.603 mas/yr, $\mu_{\mathrm{\delta}}$=$-$22.481$\pm$0.719 mas/yr, @GaiaCollaboration2016]]{}[; it]{} is consistent with an object not gravitationally bound to SAO 206462. Therefore, we conclude that the [point source]{} is a background star.

Disk imaging and photometry {#sec:disk}
===========================

We analyze [the]{} morphology and photometry of the detected disk features using the spatial and spectral information provided by the SPHERE data. A full [modeling]{} of the total intensity images of the disk will allow [a more quantitative analysis of]{} the physical [constraints,]{} but is beyond the scope of this paper.

Disk features
-------------

The spiral arms and the outer edge of the inner cavity of the disk are clearly detected in the SPHERE data [with non-aggressive differential imaging techniques]{} (top panels of Figs. \[fig:ifsim\] and \[fig:irdisim\], and Fig. \[fig:spiralfit\]), providing a nice illustration of the instrument capabilities for high-contrast imaging of faint extended sources such as circumstellar disks. [The disk is also [clearly]{} seen in individual RDI IFS images]{} (Appendix \[sec:ifsimchannels\]). Except for an increase [in]{} the disk bulk contrast with respect to the star, we do 