Shapley Supercluster Survey: Construction of the Photometric Catalogues
  and i-band Data Release
  The Shapley Supercluster Survey is a multi-wavelength survey covering an area
of ~23 deg^2 (~260 Mpc^2 at z=0.048) around the supercluster core, including
nine Abell and two poor clusters, having redshifts in the range 0.045-0.050.
The survey aims to investigate the role of the cluster-scale mass assembly on
the evolution of galaxies, mapping the effects of the environment from the
cores of the clusters to their outskirts and along the filaments. The optical
(ugri) imaging acquired with OmegaCAM on the VLT Survey Telescope is essential
to achieve the project goals providing accurate multi-band photometry for the
galaxy population down to m*+6. We describe the methodology adopted to
construct the optical catalogues and to separate extended and point-like
sources. The catalogues reach average 5sigma limiting magnitudes within a
3\arcsec diameter aperture of ugri=[24.4,24.6,24.1,23.3] and are 93% complete
down to ugri=[23.8,23.8,23.5,22.0] mag, corresponding to ~m*_r+8.5. The data
are highly uniform in terms of observing conditions and all acquired with
seeing less than 1.1 arcsec full width at half-maximum. The median seeing in
r-band is 0.6 arcsec, corresponding to 0.56 kpc h^{-1}_{70} at z=0.048. While
the observations in the u, g and r bands are still ongoing, the i-band
observations have been completed, and we present the i-band catalogue over the
whole survey area. The latter is released and it will be regularly updated,
through the use of the Virtual Observatory tools. This includes 734,319 sources
down to i=22.0 mag and it is the first optical homogeneous catalogue at such a
depth, covering the central region of the Shapley supercluster.
