Evaluation of the T/T Conditions at Gemini South using NICI AO Telemetry Data

¹ Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia, Canada V9E2E7
² Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA

^a e-mail: jean-pierre.veran@nrc-cnrc.gc.ca

Abstract

We have used NICI AO telemetry data to evaluate the T/T conditions at Gemini South and how much T/T residuals an instrument such as GPI will be able to achieve. We have found that spatial aliasing in the NICI WFS produces spurious low frequency power that does not allow us to evaluate whether windshake has a strong contribution. We have also found that the NICI data reveal vibrations at high frequency. In the case of GPI, a ∼ 2 mas rms vibration line at 279 Hz in the incoming T/T would dominate the GPI residuals. Excessive windshake and high frequency vibrations are two potential effects that could severely restrict the performance of the future ELTs unless specific controllers are implemented.