The Travels of WINERED Spectrograph

Japan to Chile

Wasatch Photonics volume phase holographic (VPH) gratings are used in telescopes around the world. In this series on astronomical spectrographs, we explore some of the telescopes and instruments in which our gratings are used, and the science they are studying.

>> WINERED is a Warm INfrared Echelle spectrograph to Realize Extreme Dispersion and sensitivity, developed by the Laboratory of Infrared High-resolution spectroscopy (LiH) at Kyoto Sangyo University for initial use at the 1.3 m Araki Telescope at Koyama Astronomical Observatory. It was relocated to the New Technology Telescope at La Silla Observatory, Chile in 20174, and finally to the Magellan Clay Telescope at Las Campanas Observatory in Chile in 2020, where it awaits new observations post-pandemic.

This dual-mode spectrograph measures the short NIR bands spanning 0.9-1.35 μm with high signal-to-noise ratio. The spectrograph features a novel non-cryogenic, high sensitivity design that can operate in wide-mode for broad spectral coverage (R = 28,000) or hires-modes (R = 80,000) for the Y-band and J-band to observe various astronomical objects such as the fields of stars, the interstellar medium, and the solar system. It uses a classic Echelle grating and a high blazed echelle grating as the primary dispersion element for wide-mode and hires-mode, respectively, employing additional cross-dispersers in the form of three Wasatch Photonics VPH gratings for both modes, with maximum diffraction efficiencies of 86 – 95%3.

High-resolution NIR spectroscopy is able to resolve atomic and molecular lines that evade detection in other wavelength regions, and is used in Doppler searches of exoplanets revolving around red dwarf stars and young stellar objects. It also better at analysis of hard-to-see stars and quasi-stellar objects. While installed at the Araki Telescope, WINERED measured abundances of various heavy metals in giant and supergiant stars5,6 and identified new absorption lines originating from heavy elements7, which will help us better understand the chemical evolution of galaxies. It has also been used to discover new diffuse interstellar bands (DIBs) in the infrared region8,9, which are believed to be absorption lines by organic molecules in interstellar matter, and to measure weak 12CO2 absorption lines in the sunlit dayside hemisphere of Venus to derive the rotational temperature10. Explore more research performed using the WINERED spectrograph on the LiH website.