AO4ELT5 Proceedings

Tracking the sodium layer altitude with GeMS in the era of NGS2

Marin, Eduardo (Gemini Observatory), Sivo, Gaetano (Gemini Observatory), Garrel, Vincent (Max Planch Institute for Extraterrestrial Physics), Gigoux, Pedro (Gemini Observatory), Moreno, Cristian (Gemini Observatory), van Dam, Marcos (Flat Wavefronts), Chinn, Brian (Gemini Observatory), Hirst, Paul (Gemini Observatory), Montes, Vanessa (Gemini Observatory), Rutten, Rene (Gemini Observatory)

Laser Guide stars are produced by the excitation of the sodium layer in the Earths Mesosphere approximately 90 KM above sea level. While these artificial sources can be used for wave front sensing the mean altitude of the sodium layer is needed in order to extract the correct focus. In the Gemini South Multi Conjugate Adaptive Optics System (GeMS), this is done by a Slow Focus Sensor (SFS) that looks at a Natural Guide Star to effectively track the mean sodium altitude. GeMS is set to enter a new era of science with an upgrade for its Natura Guide Star wave front sensor (NGS2). NGS2 is a complete replacement for the current Natural Guide Star wave front sensor (NGS). This presents an interesting challenge as the current NGS contains the SFS. With the NGS2 setup, this SFS will be removed and a suitable replacement must be found. Peripheral Wave Front Sensor one (PWFS1) a facility guider has been selected as the replacement. We will present the results of nighttime test to cross correlate the focus data obtained by the current SFS and PWFS1.

DOI: 10.26698/AO4ELT5.0090- Proceeding PDF

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