Performance and results of the COME-ON+ adaptive optics system at the ESO 3.6-m telescope

The COME-ON+ adaptive optics system was set up on the ESO 3.6-meter telescope for two technical runs (in December 1992 and April 1993) and is now routinely used for astronomical observations. This system is an upgrade of the COME-ON adaptive optics prototype system. During the technical runs, images were recorded in the V, I, J, K and L' spectral bands. Currently, the best resolution obtained is 0.1' in H (1.65 micrometers ) under bad seeing conditions (seeing > 1' and averaged wind speed > 10 m/s) and reference star magnitudes of 6 to 8. The corresponding Strehl ratio is 35%. 70% Strehl ratio was obtained at 2.2 micrometers (K band). At 0.9 micrometers (I band), in the partial correction regime, the resolution is of the order of 0.2' for 0.8' seeing and 10 m/s averaged wind speed. The optimized modal control has been used on faint reference stars. The limiting magnitude (in V band) for wavefront sensing has been measured to 14 and 15 depending on the spectral type of the reference star and the seeing conditions for a low frequency tip-tilt correction.