GOHSS: a Fibre-fed Multiobject NIR Spectrograph for the Italian Galileo Telescope

We present the concept and preliminary design of the Galileo OH Subtracted Spectrograph [GOHSS], a multifibre NIR spectrograph for faint objects. The instrument represents a collaboration between the Institute of Astronomy, Cambridge and the Observatories of Naples and Rome and will be a second-light instrument for the 3.6m Galileo telescope located on La Palma. The NIR spectrograph accomplishes OH night-sky suppression in a different way from the hardware solution used by both OHS (Maihara etal) and COHSI (Piche' et al). GOHSS provides a multiechelle design with software subtraction capable of yielding ~28 spectra in J+H bands at a spectral resolution R~3000. Such a resolution is the minimum necessary to reduce the impact of atmospheric OH lines.