Trade-offs in the visible spectrograph of the ELT instrument MOSAIC

Conference item

MOSAIC is a concept for a multi-object spectrograph for the Extremely Large Telescope (ELT). It is planned to cover the wavelength range from 460 nm to 1800 nm with two types of spectrographs, optimized for the visible and the near-infrared. There are two observing modes; multiplex mode with 200 sampling points and Integral Field Unit (IFU) mode with 10 fields. The instrument consists of 5 visible spectrographs and 5 near-infrared spectrographs. The ELT is far from diffraction limited in the visible wavelength range. Rather than developing a large and complex AO system, it was decided that the instrument will be seeing limited in the visible. Spot sizes are therefore about 2.8 mm in diameter in the ELT focal plane, and need to be sampled by multiple fibers with large core diameter. As a result, large optics is required to achieve the science requirements on spectral resolution, bandwidth and multiplex. We work in close collaboration with manufacturers to design an instrument that is feasible and meets the scientific requirements.

Authors: Janssen, A; Sokolova, E; Pragt, J; Kragt, J; Navarro, R

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Society of Photo-optical Instrumentation Engineers
• Host title: Ground-based and Airborne Instrumentation for Astronomy VII
• Journal: Ground-based and Airborne Instrumentation for Astronomy VII
• Publication date: 2018-07-10
• Acceptance date: 2018-05-15
• DOI: 10.1117/12.2313302
• ISSN: 0277-786X
• Keywords: ELT; multi-object spectrograph,; MOSAIC