| Abstract |
The Robert Stobie Spectrograph near infrared arm will provide high
throughput, low to medium resolution long slit and multi-object
spectroscopy with broadband, spectropolarimetric, and Fabry-Perot
imaging modes over a 8' diameter field of view. The wavelength range of
the instrument is 0.9-1.7 microns, and can be operated simultaneously
with the visible arm to extend the short wavelength limit to 0.32
microns. Once fielded, RSS-NIR will be the only facility instrument on
an 8-10 meter class telescope with multi-object spectroscopy capability
covering this spectral range simultaneously. RSS-NIR is scheduled to be
commissioned on the 11-meter Southern African Large Telescope in late
2012. This is an upgrade to the existing visible instrument, with which
it shares the slit plane and an ambient temperature collimator. Beyond
the collimator, the NIR arm is cooled to -40 °C, with a cryogenic
dewar containing the detector, long wavelength blocking filters, and
final camera optics. This semi-warm configuration has required extensive
upfront analysis of the instrumental thermal background levels, which
have been incorporated into the instrument performance simulator. We
present the performance predictions for spectroscopic modes of RSS-NIR
and preliminary performance estimates and NIR issues still being
addressed in the design for Fabry-Perot and polarimetric modes. |