The Department of Astronomy along with the Space Astronomy Lab and the Space Science and Engineering Center is building a near infrared (NIR) upgrade to the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope. The RSS-NIR is being developed as a complementary instrument to the existing RSS-Visible instrument for SALT facility.

SALT is a fixed-elevation, segmented-mirror-array telescope 11-meters in diameter. It is the largest single-aperture telescope in the world. The combined NIR and Vis instruments will be unique among instrumentation for large telescopes due to their capability to provide simultaneous visible and near infrared observations.

The RSS-NIR will provide high throughput, low to medium resolution multi-object spectroscopy, narrow-band imaging, and spectropolarimetry over a wavelength of 0.85 to 1.7 µm. The RSS-NIR is semi-warm, sharing a common slit plane and partial collimator with the RSS-Vis. A predewar, cooled to -30 to -40 °C, houses the final RSS-NIR collimator optic, VPH gratings, Fabry-Perot etalon, Fabry-Perot order blocking filters, polarizing beam splitter, and the first five camera optics.

The last two camera optics, long wavelength blocking filters, and the Hawaii 2RG focal plane array detector are housed in a cryogenically cooled dewar. The semi-warm design concept has long been proposed as an economical way to extend optical instruments into the NIR.

UW-Madison Astronomy Home