Fibre multi-object spectrograph

Fibre multi-object spectrograph (FMOS) is facility instrument for the Subaru Telescope on Mauna Kea in Hawaii.

The instrument consists of a complex fibre-optic positioning system mounted at the prime focus of the telescope.

The instrument will be used to look at the light from up to 400 stars or galaxies simultaneously over a field of view of 30 arcminutes (about the size of the full moon on the sky).

The instrument will be used for a number of key programmes, including galaxy formation and evolution and dark energy via a measurement of the rate at which the universe is expanding.

[needs update] The spectrographs use a technique called OH-suppression to increase the sensitivity of the observations: The incoming light from the fibres is dispersed to a relatively high resolution and this spectrum forms an image on a pair of spherical mirrors which have been etched at the positions corresponding to the bright OH-lines.