GRACES: Gemini remote access to CFHT ESPaDOnS Spectrograph through the longest astronomical fiber ever made (Experimental phase completed.)

TL;DR

GRACES successfully demonstrated high-resolution spectroscopy using a 270-meter optical fiber link between Gemini North and CFHT, enabling sensitive observations of faint astronomical targets with efficient data acquisition.

Contribution

This paper reports the first successful implementation of a long optical fiber feed for high-resolution spectroscopy, connecting Gemini North to CFHT's ESPaDOnS spectrograph.

Findings

Achieved spectral resolution of R=40,000 to 66,000 across 400-1000 nm.

Delivered spectra with 85% maximum transmittance at 800 nm.

Sensitive to targets fainter than 21st magnitude in 1 hour.

Abstract

The Gemini Remote Access to CFHT ESPaDONS Spectrograph has achieved first light of its experimental phase in May 2014. It successfully collected light from the Gemini North telescope and sent it through two 270 m optical fibers to the the ESPaDOnS spectrograph at CFHT to deliver high-resolution spectroscopy across the optical region. The fibers gave an average focal ratio degradation of 14% on sky, and a maximum transmittance of 85% at 800nm. GRACES achieved delivering spectra with a resolution power of R = 40,000 and R = 66,000 between 400 and 1,000 nm. It has a ~8% throughput and is sensitive to target fainter than 21st mag in 1 hour. The average acquisition time of a target is around 10 min. This project is a great example of a productive collaboration between two observatories on Maunakea that was successful due to the reciprocal involvement of the Gemini, CFHT, and NRC Herzberg teams, and all the staff involved closely or indirectly.