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GNIRS was built by NOAO in Tucson, Arizona and delivered to Cerro Pachon in late October 2003. Commissioning of the majority of the modes took place in stages during 2004.  GNIRS was first made available for science use in 2004B. The instrument was damaged in 2007 while at Cerro Pachon and was repaired at Gemini North. Since 2010 it has been available for use on the Gemini North telescope.

GNIRS offers a wide variety of spectroscopic capabilities. These include long-slit (single order) spectroscopy within the 1.0-5.4 µm range at 2-pixel spectral resolving powers, R, of approximately 1700, 5000 and 18000 with a choice of two pixel scales (0.15"/pix and 0.05"/pix), and cross-dispersed spectroscopy giving complete 0.9-2.5 µm coverage at R~1700 and partial coverage at R~5000. A variety of slit widths from 0.10 to 1.0 arcsec are available. The different pixel scales are achieved with four cold-changeable cameras of "long" and "short" focal lengths optimized for "blue" (0.9-2.5 µm) and "red" (2.8-5.4 wavelengths. GNIRS also has limited imaging capabilities. The instrument can be used with ALTAIR (adaptive optics - utilizing either a natural or laser guide star) from 1 µm to 2.5 µm. Performance of ALTAIR is poor in the 3 - 5 µm range.

The Instrument Scientist for GNIRS is Andrew Stephens. Gemini staff who also support GNIRS include Marie Lemoine-Busserolle, Trent Dupuy, Tom Geballe, Meg Schwamb, Matt Taylor, and Siyi Xu. The team can be contacted at


See the Status and Availability pages for the most recent news and older news items.

GNIRS science highlights

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How to use these pages

The GNIRS pages are organized as follows.

  • Status and Availability:Recent news concerning the instrument
  • Spectroscopy: Characteristics of GNIRS' long slit and cross-dispersed spectroscopic modes, grating and camera configurations, and filters; and guidelines on how best to use the instrument.
  • Imaging: Brief description of GNIRS' imaging mode.
  • Sensitivity and Overheads: Integration time calculator, sensitivity tables, and details of observing overheads
  • Guiding Options: Guiding considerations, and wavefront sensors available for use with GNIRS
  • Calibration: Info on GCAL flats and arcs, standard stars, and baseline calibrations
  • Observation Preparation: How to configure GNIRS in the Observing Tool
  • Data Format and Reduction: Examples of GNIRS data and links to data reduction resources
  • System Verification: 2010B call for SV proposals, list of accepted programs, and results.
  • Documents: GNIRS optical layout; design documents and references

Also see the Near-IR Resources section, which contains generic information about observing at 1-5 µm as well as details about calibrations, standard stars, etc. that apply to Gemini's near-IR instruments.


GNIRS on Gemini-South


Click on the image to see a close-up view of GNIRS (on Gemini South)