Instrumentation & Device Development

EXES: mid-IR spectrograph


HETDEX: Dark Energy Experiment


Micromachined Silicon Diffractive Optics

IGRINS: Immersion Grating Infrared Spectrograph

IGRINS, the Immersion Grating INfrared Spectrometer, is a cross-dispersed near-IR spectrograph with a resolving power R=λ/Δλ = 40,000 (Yuk et al. 2010). It can observe all of the H and K windows in a single exposure. This coverage represents a revolutionary increase in spectral grasp (instantaneous spectral coverage) at high resolution enabled by the use of a silicon immersion echelle grating and two 2Kx2K infrared detectors. IGRINS has an infrared slit-viewing camera for rapid acquisition. It has a single observing mode and no cryogenic moving parts. This simple design will make it easy for new observers to master and will allow the instrument team to provide a simple data reduction pipeline. By making use of the latest low-noise detectors and of a Si immersion grating and VPH cross-dispersers, IGRINS will have the sensitivity to attack a broad range of astronomical problems (see Astronomy with IGRINS page (link eher)) at its principal site, the 2.7m Harlan Smith Telescope at McDonald Observatory. At McDonald, the instrument will sit at the Cassegrain focus of the 2.7 meter and the slit size will be 1”x14”, with 3.5 pixel sampling across the slit. Further technical details are available in Yuk et al. (2010, Proc. SPIE 7735).

IGRINS is a collaboration of the University of Texas, the Korea Astronomy and Space Science Institute KASI. D. Jaffe (UT) is the PI and Insoo Yuk (KASI) is Deputy-PI. The instrument will be available at McDonald Observatory on a shared-risk basis in the second trimester of 2014. IGRINS is a PI instrument. It is open for use to anyone who obtains time at McDonald Observatory, with the restriction that a member of the instrument team must be included in any proposal.

For further information feel free to contact the PI or Deputy PI or the UT commissioning scientist, Dr. Michael Pavel.

Figure 1: Optical layout for IGRINS. All parts shown are within the cryogenic part of the instrument.

Figure 2:(left) K-band echellogram. The box shows the 2048 array. The dashed lines give the nominal ends of the orders. The order spacings on the right are for a 4m telescope. (right) Spot diagrams for the H band. The boxes are 2x2 pixels. The slit width is 3.6 pixels.

Figure 3: CAD drawing of the IGRINS optical bench. The longest dimension is ~0.9m. Light enters at top center. The immersion grating is in the pink housing at the center and the H and K band detectors are at the lower left and right.

Figure 4: IGRINS optical bench during test assembly. The H and K band cameras and detectors are in the foreground.

Figure 5: Fully assembled IGRINS cryostat. The black box on the right contains the calibration system including line and continuum lamps.