Gemini Multi-Object Spectrograph (GMOS)

The back end of the Gemini North telescope, tilted down, showing the suite of scientific instruments mounted on the Instrument Support Structure (ISS). GMOS is on the right-hand port. 

The GMOS instruments include GMOS-N at the Gemini North telescope on Maunakea in Hawai‘i and GMOS-S at Gemini South on Cerro Pachón in Chile. Their construction was a collaboration between the Astronomy Technology Centre at the Royal Observatory Edinburgh and the University of Durham in the UK, and the Herzberg Institute of Astrophysics in Canada. They are the International Gemini Observatory’s twin workhorse instruments for observations at visible wavelengths. They can be used as either a spectrograph or an imager. While there are slight differences, the information here applies to both instruments. 

GMOS instruments detect light in the 0.36–1.03 micrometer wavelength range and operate in four modes: three spectroscopic modes — long slit mode, multi-object mode, which captures spectra from many objects simultaneously, integral field spectroscopy mode, which collects spectra from a two-dimensional area of the sky — and an imaging mode. This versatility allows for a wide range of astronomical observations.

The mechanical system is designed to minimize tilts between optical components so that the only effect of flexure is a slow motion of the detector perpendicular to the optical path. This allows the detector to simply be repositioned to compensate for any warping of the instrument due to gravity in real time, keeping the images as sharp as possible.

More on GMOS.

The Gemini Multi-Object Spectrograph (GMOS) mounted on Gemini South on Cerro Pachón in Chile.
Credit: CTIO/NOIRLab/NSF/AURA/D. Munizaga

Science Highlights of GMOS-N

• Gemini North Spies Ultra-Faint Fossil Galaxy Discovered on Outskirts of Andromeda
• Astronomers Uncover Briefest Supernova-Powered Gamma-Ray Burst
• Black Hole Pairs Found in Distant Merging Galaxies

Science Highlights of GMOS-S

• First Known Interstellar Visitor is an “Oddball”
• Exploring a Fast Radio Burst in Three Dimensions

Quick Facts