We present I -band Surface Brightness Fluctuations ( SBF ) measurements for 16 early type galaxies ( 3 giants , 13 dwarfs ) in the central region of the Hydra cluster , based on deep photometric data in 7 fields obtained with VLT FORS1 .
From the SBF-distances to the galaxies in our sample we estimate the distance of the Hydra cluster to be 41.2 \pm 1.4 Mpc ( ( m - M ) = 33.07 \pm 0.07 mag ) .
Based on an improved correction for fluctuations from undetected point sources , we revise the SBF-distance to the Centaurus cluster from Mieske & Hilker ( [ 2003b ] ) upwards by 10 % to 45.3 \pm 2.0 Mpc ( ( m - M ) = 33.28 \pm 0.09 mag ) .
The relative distance modulus of the two clusters then is ( m - M ) _ { Cen } - ( m - M ) _ { Hyd } = 0.21 \pm 0.11 mag .
With H _ { 0 } = 72 \pm 4 km s ^ { -1 } Mpc ^ { -1 } , we estimate a positive peculiar velocity of 1225 \pm 235 km s ^ { -1 } for Hydra and 210 \pm 295 km s ^ { -1 } for the Cen30 component of Centaurus .
Allowing for a thermal velocity dispersion of 200 km s ^ { -1 } , this rules out a common peculiar flow velocity for both clusters at 98 % confidence .
We find that the 9 \times 10 ^ { 15 } M _ { \sun } “ Great Attractor ” from the flow study of Tonry et al .
( [ 2000 ] ) at a distance of \simeq 45 Mpc can explain the observed peculiar velocities if shifted about 15 \degr towards the Hydra cluster position .
Our results are inconsistent at 94 % confidence with a scenario where the Centaurus cluster is identical to the GA .
In order to better restrict partially degenerate Great Attractor parameters like its mass and distance , a recalculation of the local flow model with updated distance information over a larger area than covered by us would be needed .