Meson Photoproduction at Graal

Precise measurements of the differential cross section and the beam polarization asymmetry Σ have been obtained by the GRAAL collaboration for the vec γ { + }p{ } -> { }η { + }p and the vec γ { + }p{ } -> { }π ⁰ { + }p reactions, at incoming photon energies up to 1.48 GeV. Preliminary data are presented and compared with different theoretical calculations. First measurements of the Σ observable are also available for the bar γ { + }p{ } -> { }K^ + Λ reaction channel.