Multi-Object Infrared Camera and Spectrograph (MOIRCS) for the Subaru Telescope* I. Imaging

摘要

MOIRCSisafullycryogenicnear-infraredinstrumentforthe8.2mSubaruTelescope.MOIRCShastwoobservationmodes:awide-fieldimagingmodeandamultiobjectspectroscopymode.Thispaperdescribestheimagingmode,itsspecifications,andactualperformancesthatweconfirmedthroughlaboratorytestsandcommissioningobservations.Theimagingmodeprovidesa4'$$ imes$$7'fieldofviewwithapixelscaleof0a€?.117pixel$$^{-1}$$inthewavelengthrangeof0.85to2.5$$mu$$usingcooledopticsandtwo2048$$ imes$$2048HgCdTeHAWAII-2focalplanearrays.Good-qualityimagesareobtainedovertheentirefieldofviewwithpracticallynochromaticaberration.Thelimitingmagnitudesforapointsourceestimatedfromobservedbackgroundbrightnessandthroughputare23.7inthe$$J$$band,23.0inthe$$H$$band,and22.6inthe$$K_{ ms}$$band(Vega)with$$S/N$$$$=$$5,0a€?.5seeing,1a€?.0aperture,and1hrexposure.