Euclid Assessment Study Report for the ESA Cosmic Visions
  Euclid is a proposed high-precision survey mission to map the geometry of the
Dark Universe with demonstrated feasibility. Euclid's Visible - Near-InfraRed
imaging and spectroscopy of the extragalactic sky will further produce
extensive legacy science to the boundaries of the visible universe. The mission
is optimised for two primary cosmological probes: Weak gravitational Lensing
(WL) and Baryonic Acoustic Oscillations (BAO). Euclid's wide survey will cover
20,000 deg2, measuring shapes and redshifts of galaxies to redshift 2. For weak
lensing, Euclid will measure the shape of over 2 billion galaxies with a
density of 30-40 resolved galaxies per arcmin2 in one broad visible R+I+Z band
(550-920 nm) down to AB mag 24.5 (10sigma). The photometric redshifts for these
galaxies are derived from three additional Euclid NIR bands (Y,J,H in the range
0.92-2.0 micron) reaching AB mag 24 (5sigma) in each, complemented by
photometry from ground based surveys. The BAO are determined from a NIR
spectroscopic survey with a redshift accuracy of dz/(1+z) =0.001. The baseline
payload consists of a Korsch telescope with a primary mirror of 1.2 m diameter
and is designed to provide a large field of view (0.5 deg2) to three scientific
instruments: (1) VIS: a CCD based optical imaging channel, (2) NIP: a NIR
imaging photometry channel, and (3) NIS: a NIR spectrometric channel. This
report presents an overview of the assessment study phase of the Euclid
candidate M-class Cosmic Vision mission; it will provide a description of the
Euclid science objectives, the mission implementation and payload, and the
envisaged data handling.
