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arXiv · 1002.3151

S-DIMM+ height characterization of day-time seeing using solar granulation

G. B. Scharmer·T. I. M. van Werkhoven
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Abstract

To evaluate site quality and to develop multi-conjugative adaptive optics systems for future large solar telescopes, characterization of contributions to seeing from heights up to at least 12 km above the telescope is needed. We describe a method for evaluating contributions to seeing from different layers along the line-of-sight to the Sun. The method is based on Shack Hartmann wavefront sensor data recorded over a large field-of-view with solar granulation and uses only measurements of differential image displacements from individual exposures, such that the measurements are not degraded by residual tip-tilt errors. We conclude that the proposed method allows good measurements when Fried's parameter r_0 is larger than about 7.5 cm for the ground layer and that these measurements should provide valuable information for site selection and multi-conjugate development for the future European Solar Telescope. A major limitation is the large field of view presently used for wavefront sensing, leading to uncomfortably large uncertainties in r_0 at 30 km distance.

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G. B. Scharmer, T. I. M. van Werkhoven. 2010-02-16. S-DIMM+ height characterization of day-time seeing using solar granulation. https://doi.org/10.1051/0004-6361/200913791

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