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International audienceWe present the results of monitoring the speed of optical turbulent layers in the atmosphere above San Pedro Mártir, Mexico, during 15 nights in 2000 May. The data were obtained using the generalized scintillation detection and ranging technique (generalized SCIDAR), developed at Nice University. This paper constitutes the second in a series. The first paper presents results concerning measurements of optical turbulence strength obtained at the same site and time. The principal results of the present article are as follows: (1) The wind profiles remain stable during each night. (2) No correlation between the turbulence intensity C2N and the speed of the turbulent layers, V, is detected for speeds lower than ~45 m s-1. Above that speed, which was only exceeded in the jet-stream layer on one night, the optical turbulence strength is seen to increase. (3) Layers in the first 4 km and higher than 16 km above sea level are similarly slow, with median speeds of 8.6 and 9.6 m s-1, respectively. (4) Between 9 and 16 km, where the jet stream flows on some of the nights, the median wind speed is 26.0 m s-1. (5) From simultaneous measurements of C2N(h) and V(h), we compute the temporal coherence of the turbulence, layer by layer, in 500 m thick layers. This is the first time that such data have been published. For a multiconjugate adaptive optics system, our measurements show that the temporal responses of three deformable mirrors conjugated on the ground and at 6 km and 13 km above sea level, each one correcting for the turbulence in 500 m thick layers, would need to be 64, 40, and 20 ms. (6) The vertical variation of V dominates the vertical variation of the coherence time. (7) For the first time, we compare wind velocity profiles obtained from three different sources: generalized SCIDAR, NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data, and meteorological research balloons. The comparison shows excellent agreement in both the modulus and the direction of the wind velocity

We present the results of our search for the faint galaxies near the end of the Reionisation Epoch. This has been done using very deep OSIRIS images obtained at the Gran Telescopio Canarias (GTC). Our observations focus around two close, massive Lyman Alpha Emitters (LAEs) at redshift 6.5, discovered in the SXDS field within a large-scale overdense region (Ouchi et al. 2010). The total GTC observing time in three medium band filters (F883w35, F913w25 and F941w33) is over 34 hours covering 7.0 × 8.5 arcmin 2 (or ∼ 30, 000 Mpc 3 at z = 6.5). In addition to the two spectroscopically confirmed LAEs in the field, we have identified 45 other LAE candidates. The preliminary luminosity function derived from our observations, assuming a spectroscopic confirmation success rate of 2 3 as in previous surveys, suggests this area is about 2 times denser than the general field galaxy population at z = 6.5. If confirmed spectroscopically, our results will imply the discovery of one of the earliest protoclusters in the universe, which will evolve to resemble the most massive galaxy clusters today.

We report the development and first results of an instrument called Low Layer SCIDAR (Scintillation Detection and Ranging) (LOLAS) which is aimed at the measurement of optical‐turbulence profiles in the atmospheric boundary layer with high altitude resolution. The method is based on the Generalized SCIDAR (GS) concept, but unlike the GS instruments which need a 1‐m or larger telescope, LOLAS is implemented on a dedicated 40‐cm telescope, making it an independent instrument. The system is designed for widely separated double‐star targets, which enables the high altitude resolution. Using a 200‐arcsec‐separation double star, we have obtained turbulence profiles with unprecedented 12‐m resolution. The system incorporates necessary novel algorithms for autoguiding, autofocus and image stabilization. The results presented here were obtained at Mauna Kea Observatory. They show LOLAS capabilities but cannot be considered as representative of the site. A forthcoming paper will be devoted to the site characterization. The instrument was built as part of the Ground Layer Turbulence Monitoring Campaign on Mauna Kea for Gemini Observatory.

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