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Subaru Seminars are usually held in Room 104 of the Hilo Base Facility, adjacent to the main lobby. Everyone is welcome to attend. If you are interested in giving a seminar, please contact Subaru seminar organizers (Tae-Soo Pyo, Sherry Yeh, Nagayoshi Ohashi) by email : (please change"_at" to @).

July 25, Monday, 11 am in 104

" The CHARIS Integral Field Spectrograph for Subaru "

Tyler Groff

(Princeton Unviversity)

The Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) is an integral field spectrograph (IFS) that has been built for the Subaru telescope. CHARIS has two imaging modes; the 'high-resolution' mode is R82, R69, and R82 in J, H, and K bands respectively while the 'low-resolution' discovery mode uses a second 'low-resolution' prism with R19 spanning 1.15-2.37 microns (J+H+K bands). The discovery mode is meant to augment the low inner working angle of the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) adaptive optics system, which feeds CHARIS a coronagraphic image. CHARIS constrains spectral crosstalk through several key aspects of the optical design. We report on the measured repeatability and stability of these mechanisms, measurements of spectral crosstalk in the instrument, and the propagation of these errors through the data pipeline. Another key design feature of CHARIS is the prism, which pairs Barium Fluoride with Ohara L-BBH2 high index glass. The dispersion of the prism is significantly more uniform than other glass choices, and the CHARIS prisms represent the first NIR astronomical instrument that uses L-BBH2 as the high index material. We will also discuss the lessons learned during the testing process and their impact on future high-contrast imaging spectrographs for wavefront control.

Seminars are also held at JAC, CFHT, and IfA.

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