EAGLE multi-object AO concept study for the E-ELT

EAGLE is the multi-object spatially-resolved near-IR spectrograph instrument concept for the E- ELT, relying on a distributed Adaptive Optics, so-called Multi Object Adaptive Optics. This paper presents the results of a phase A study. Using 84x84 actuator deformable mirrors, the performed analysis demonstrates that 6 laser guide stars and up to 5 natural guide stars of magnitude R < 17, picked-up in a 7.3 � diameter patrol field of view, allow us to obtain an overall performance in terms of Ensquared Energy of 35% in a 75x75mas 2 spaxel at H band whatever the target direction in the centred 5 � science field for median seeing conditions. The computed sky coverage at galactic latitudes |b |∼ 60 is close to 90%.