The preslit system of GIANO-TNG

ABSTRACT GIANO-TNG is an ultra-stable infrared (0.9-2.5 µ m) high resolution cross-dispersed spectrometer designed tooperate at a “xed position relative to the telescope axis. It therefore requires a pre-slit opto-mechanical systemwhich takes care of “eld de-rotation and auto-guiding. Taking advantage of the structure already existing forSARG (the high resolution optical spectrometer of the Telescopio Nazionale Galileo, TNG) we are developing asystem which provides a large (2 arcmin) “eld of view for oset guiding and includes, as separate and selectableelements, a gas absorption cell and a polarimetric module where the analyzers work in a collimated beam.Keywords: Ground based infrared instrumentation, infrared spectrometers 1. INTRODUCTION GIANO is a cross-dispersed IR high resolution ( RS =23,000 and R =46,000 with a 0.5Ž slit) spectrometer coveringmost of the 0.9 2.5 µ m range in a single shot. It also provides a low resolution mode (RS 400) with completespectral coverage from 0.75 to 2.5 µ m.