  AA Tau is a well-studied, nearby classical T Tauri star, which is viewed
almost edge-on. A warp in its inner disk periodically eclipses the central
star, causing a clear modulation of its optical light curve. The system
underwent a major dimming event beginning in 2011 caused by an extra absorber,
which is most likely associated with additional disk material in the line of
sight toward the central source. We present new XMM-Newton X-ray, Hubble Space
Telescope FUV, and ground based optical and near-infrared data of the system
obtained in 2013 during the long-lasting dim phase. The line width decrease of
the fluorescent H$_2$ disk emission shows that the extra absorber is located at
$r>1\,$au. Comparison of X-ray absorption ($N_H$) with dust extinction ($A_V$),
as derived from measurements obtained one inner disk orbit (eight days) after
the X-ray measurement, indicates that the gas-to-dust ratio as probed by the
$N_H$ to $A_V$ ratio of the extra absorber is compatible with the ISM ratio.
Combining both results suggests that the extra absorber, i.e., material at
$r>1\,$au, has no significant gas excess in contrast to the elevated
gas-to-dust ratio previously derived for material in the inner region
($\lesssim0.1\,$au).
