We report the discovery of a potentially major supercluster that extends across the Galactic Plane in the constellation of Vela , at a mean recessional velocity of \sim 18 000 km s ^ { -1 } .
Recent multi-object spectroscopic observations of this Vela Supercluster ( VSCL ) , using AAOmega+2dF and the Southern African Large Telescope , confirm an extended galaxy overdensity in the Zone of Avoidance ( ZOA ) located where residual bulk flows predict a considerable mass excess .
We present a preliminary analysis of \sim 4500 new spectroscopic galaxy redshifts obtained in the ZOA centred on the Vela region ( l = 272 \fdg 5 \pm 20 \degr,b = 0 \degr \pm 10 \degr ) .
The presently sparsely-sampled dataset traces an overdensity that covers 25 \degr in Galactic longitude on either side of the Plane , suggesting an extent of 25 \degr \times 20 \degr , corresponding to \sim 115 \times 90 h _ { 70 } Mpc at the supercluster redshift .
In redshift space , the overdensity appears to consist of two merging wall-like structures , interspersed with clusters and groups .
Both the velocity histogram and the morphology of the multi-branching wall structure are consistent with a supercluster classification . K _ { s } ^ { o } galaxy counts show an enhancement of \sim 1.2 over the survey area for galaxies brighter than M _ { K } ^ { * } at the VSCL distance , and a galaxy overdensity of \delta = 0.50 – 0.77 within a photometric redshift shell around the VSCL , when compared to various Two-Micron All-Sky Survey samples .
Taking account of selection effects , the VSCL is estimated to contribute v _ { \mathrm { LG } } \ga 50 km s ^ { -1 } to the motion of the Local Group .