  Studying circumbinary disks is critical to understanding the formation
mechanisms of binary stars. While optical or mid-infrared images reveal the
scattered mission, millimeter observations provide direct measurements of the
dust thermal emission. We study the properties of the circumbinary disk around
the well-known, multiple young stellar object GG Tau with the highest possible
sensitivity and spatial resolution. We mapped the continuum emission of GG Tau
at 267 GHz using the IRAM Plateau de Bure interferometer equipped with upgraded
receivers and LO systems. An angular resolution of 0.45"x0.25" was achieved,
corresponding to a linear resolution of 65x35 AU. The GG Tau A circumbinary
disk is observed as an extremely clearly defined narrow ring. The width of the
ring is not resolved. Emission from the central binary is detected and clearly
separated from the ring: it coincides with the GG Tau Aa position and may
therefore trace a circumstellar disk around this star. The mass ratio of the
circumbinary to circumprimary material is ~80.
