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Proceedings Paper

GMTNIRS: progress toward the Giant Magellan Telescope near-infrared spectrograph
Author(s): Daniel T. Jaffe; Stuart Barnes; Cynthia Brooks; Hanshin Lee; Gregory Mace; Soojong Pak; Byeong-Gon Park; Chan Park
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Paper Abstract

GMTNIRS is a first-generation instrument for the Giant Magellan Telescope. It is a high-resolution spectrograph that will cover the 1.15-5.3 μm range in a single exposure with R=60,000 in the J, H, and K bands and R=85,000 in the L and M bands. It resides on the GMT’s rotating instrument platform and employs the facility adaptive optics system. The GMTNIRS design is evolving in response to emerging science problems, particularly in the area of exoplanet atmospheres. Our design revisions also derive lessons from GMTNIRS’ highly successful forerunner instrument, IGRINS. Technical changes also drive evolution of the design. It has proven impractical to manufacture 200mm long immersion gratings at the necessary precision. The success of primary mirror phasing efforts has removed the need for a very wide entrance slit that we would have needed to accommodate the Airy pattern of individual segments at the shortest operating wavelengths. The high efficiency of our double-side coated JWST grisms introduces the possibility of transmissive cross-dispersers at L and M. These changes move us toward a design with almost the same R as presented in our previous work but with a much more compact physical envelope. We will report on the optimization of the instrument design with these technical changes in mind. We are also producing the critical Si immersion gratings. The grating production is well under way and includes manufacture of H and K gratings and process development for the precision needed in the J band and for the manufacture of larger gratings for the L and M band. The development of GMTNIRS is on track with the results from IGRINS and the progress in the lab giving us substantial assurance that the new instrument can meet its performance goals.

Paper Details

Date Published: 9 August 2016
PDF: 9 pages
Proc. SPIE 9908, Ground-based and Airborne Instrumentation for Astronomy VI, 990821 (9 August 2016); doi: 10.1117/12.2232994
Show Author Affiliations
Daniel T. Jaffe, The Univ. of Texas at Austin (United States)
Stuart Barnes, Stuart Barnes Optical Design (Germany)
Cynthia Brooks, McDonald Observatory, The Univ. of Texas at Austin (United States)
Hanshin Lee, McDonald Observatory, The Univ. of Texas at Austin (United States)
Gregory Mace, McDonald Observatory, The Univ. of Texas at Austin (United States)
Soojong Pak, Kyung Hee Univ. (Korea, Republic of)
Byeong-Gon Park, Korea Astronomy and Space Science Institute (Korea, Republic of)
Chan Park, Korea Astronomy and Space Science Institute (Korea, Republic of)


Published in SPIE Proceedings Vol. 9908:
Ground-based and Airborne Instrumentation for Astronomy VI
Christopher J. Evans; Luc Simard; Hideki Takami, Editor(s)

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