  Previous studies of the galaxy and galaxy cluster distribution in the local
Universe found indications for a large extension of the Local Supercluster up
to a radius of 190 h_70^-1 Mpc. We are using our large and highly complete
CLASSIX survey of X-ray luminous galaxy clusters detected in the ROSAT All Sky
Survey to trace the matter distribution in the local Universe and to explore
the size of the flattened local density structure associated with the Local
Supercluster. The Local Supercluster is oriented almost perpendicular to the
Galactic plane. Since Galactic extinction increases towards the Galactic plane,
objects are on average more easily visible perpendicular to the plane than
close to it, also producing an apparent concentration of objects along the
Local Supercluster. We can correct for this bias by a careful treatment of the
survey selection function. We find a significant overdensity of clusters in a
flattened structure along the Supergalactic plane with a thickness of about 50
Mpc and an extent of about 100 Mpc radius. Structures at a distance larger than
100 Mpc are not correlated to the Local Supercluster any more. The matter
density contrast of the local superstructure to the surroundings is about a
factor of 1.3 - 2.3. Within the Supergalactic plane the matter is concentrated
mostly in two superclusters, the Perseus-Pisces Chain and Hydra-Centaurus
supercluster. We have shown in our earlier work that the local Universe in a
region with a radius of 100 - 170 Mpc has a lower density than the cosmic mean.
For this reason, the Local Supercluster is not overdense with respect to the
cosmic mean density. Therefore this local superstructure will not collapse as a
whole in the future, but rather fragment.
