First results on a Cn2 profiler for GeMS


Angela Cortes (1), Benoit Neichel (2), Francois Rigaut (2), Dani Guzman (1), Andres Guesalaga (1)


(1)Pontificia Universidad Católica de Chile, 4860 Vicuna Mackenna, Casilla 7820436, Santiago, Chile ; (2)Gemini Observatory Southern Operations Center, Colina el Pino s/n, Casilla 603, La Serena, Chile


GeMS (the Gemini MCAO System) is a facility instrument for the Gemini-South telescope, currently in its final commissioning phases. The system includes 5 laser guide stars, 3 natural guidestars, 3 deformable mirrors optically conjugated at 0, 4.5 and 9km and 1 tip-tilt mirror. Among these unique features, a Cn2 Slodar Profiler is being implemented. The Cn2 profile is reconstructed from the slopes seen by the 5 high order WFS, each one pointing in a LGS direction. Residuals from the 16x16 subapertures WFSs and DM commands are used to obtain pseudo-open loop data for SLODAR, allowing us to reconstruct up 16 layers. The first part of this paper describes the algorithms used for this purpose and the results obtained from simulations and from artificially generated turbulence, resulting from exiting the 3 DMs. These latter have been extensively used to calibrate the method in a controlled environment. The second part of the paper presents the first on-sky results obtained during commissioning nights. In particular, we compare these results with external data obtained from a MASS/DIMM instrument.

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