On-sky vibration environment for the Gemini Planet Imager and mitigation effort

TL;DR

This paper analyzes the vibration environment affecting the Gemini Planet Imager during on-sky observations and discusses mitigation strategies to improve high-contrast imaging performance.

Contribution

It provides a comprehensive overview of vibration sources, measurements, and mitigation efforts for the GPI instrument at Gemini South.

Findings

Vibration sources identified from instrument and external sensors.

Mitigation methods include passive damping and Kalman filtering.

Initial results show reduced vibration impact on image quality.

Abstract

The Gemini Planet Imager (GPI) entered on-sky commissioning and had its first-light at the Gemini South (GS) telescope in November 2013. GPI is an extreme adaptive optics (XAO), high-contrast imager and integral-field spectrograph dedicated to the direct detection of hot exo-planets down to a Jupiter mass. The performance of the apodized pupil Lyot coronagraph depends critically upon the residual wavefront error (design goal of 60 nm RMS with 5 mas RMS tip/tilt), and therefore is most sensitive to vibration (internal or external) of Gemini's instrument suite. Excess vibration can be mitigated by a variety of methods such as passive or active dampening at the instrument or telescope structure or Kalman filtering of specific frequencies with the AO control loop. Understanding the sources, magnitudes and impact of vibration is key to mitigation. This paper gives an overview of related investigations based on instrument data (GPI AO module) as well as external data from accelerometer sensors placed at different locations on the GS telescope structure. We report the status of related mitigation efforts, and present corresponding results.