Imaging the dense stellar cluster R136 with VLT-MAD

Abstract

We evaluate the performance of the Multi-conjugate Adaptive optics Demonstrator (MAD) from H and K s imaging of 30 Doradus in the Large Magellanic Cloud. Maps of the full-width half maximum (FWHM) of point sources in the H and K s images are presented, together with maps of the Strehl ratio achieved in the K s -band observations. Each of the three natural guide stars was at the edge of the MAD field-of-view, and the observations were obtained at relatively large airmass (1.4-1.6). Even so, the Strehl ratio achieved in the second pointing (best-placed compared to the reference stars) ranged from 15% to an impressive 30%. Preliminary photometric calibration of the first pointing indicates 5σ sensitivities of K s ∼21.75 and H∼22.25 (from 22 and 12 min exposures, respectively).