CYRA - The cryogenic infrared spectrograph for the Goode Solar Telescope in Big Bear

Xu Yang, Wenda Cao, Nicolas Gorceix, Claude Plymate, Sergey Shumko, Xian Yong Bai, Matt Penn, Thomas Ayres, Roy Coulter, Philip R. Goode

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Scopus citations


CYRA (CrYogenic solar spectrogRAph) is a facility instrument of the 1.6-meter Goode Solar Telescope (GST) at the Big Bear Solar Observatory (BBSO). CYRA focuses on the study of the near-infrared solar spectrum between 1 and 5 microns, an under-explored region which is not only fertile ground for photospheric magnetic diagnostics but also allows a unique window into the chromosphere lying atop the photosphere. CYRA is the first-ever fully cryogenic spectrograph in any solar observatory with its two predecessors, on the McMath-Pierce and Mees Telescopes, being based on warm optics except for the detectors and order sorting filters. CYRA is used to probe magnetic fields in various solar features and the quiet photosphere. CYRA measurements will allow new and better 3D extrapolations of the solar magnetic field and will provide more accurate boundary conditions for solar activity models. The superior spectral resolution of 150,000 and better allows enhanced observations of the chromosphere in the carbon monoxide (CO) spectral bands and will yield a better understanding of energy transport in the solar atmosphere. CYRA is divided into two optical sub-systems: The Fore-Optics Module and the Spectrograph. The Spectrograph is the heart of the instrument and contains the IR detector, grating, slits, filters, and imaging optics all in a cryogenically cooled Dewar (cryostat). The sensor is a 2048 by 2048 pixel HAWAII 2 array produced by Teledyne Scientific & Imaging, LLC. The cryostat interior and the readout electronics are maintained at 90 Kelvin by helium refrigerant-based cryo-coolers, while the IR array is cooled to 30 Kelvin. The Fore-Optics Module de-rotates and stabilizes the solar image, provides scanning capabilities and transfers the GST image to the Spectrograph. CYRA has been installed and is undergoing its commissioning phase. This paper reports on the design, implementation, and operation of CYRA in detail. The preliminary scientific results have been highlighted as well.

Original languageEnglish (US)
Title of host publicationGround-Based and Airborne Instrumentation for Astronomy VIII
EditorsChristopher J. Evans, Julia J. Bryant, Kentaro Motohara
ISBN (Electronic)9781510636811
StatePublished - 2020
EventGround-Based and Airborne Instrumentation for Astronomy VIII 2020 - Virtual, Online, United States
Duration: Dec 14 2020Dec 22 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceGround-Based and Airborne Instrumentation for Astronomy VIII 2020
Country/TerritoryUnited States
CityVirtual, Online

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


  • Cryogenic
  • Infrared
  • Magnetic field
  • Solar physics
  • Spectrograph


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