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WFOS instrument trade study: slicer vs. fiber instrument concept designs and results (Conference Presentation)
Author(s): Kevin Bundy; Maureen Savage; Renate Kupke; Nicholas MacDonald; Kyle Westfall; Matthew Radovan; Zheng Cai; Brian Digiorgio; Richard Dekany; Devika Divakar; Jason Fucik; Hangxin Ji; Satoshi Miyazaki; Shinobu Ozaki; Andrew Phillips; Namrata Roy; Roger Smith; Arun Surya; S. Sriram; Sivarani Thirupathi; Toshihiro Tsuzuki
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Paper Abstract

The Wide Field Optical Spectrometer (WFOS) is a seeing limited, multi-object spectrograph and first light instrument for the Thirty Meter Telescope (TMT) scheduled for first observations in 2027. The spectrograph will deliver a minimum resolution of R~5,000 over a simultaneous wavelength range of 310 nm to 1,000 nm with a multiplexing goal of between 20 and 700 targets. The WFOS team consisting of partners in China, India, Japan, and the United States has completed a trade study of two competing concepts intended to meet the design requirements derived from the WFOS detailed science case. The first of these design concepts is a traditional slit mask instrument capable of delivering R~1,000 for up to 100 simultaneous targets using 1 x 7 arc second slits, and a novel focal plane slicing method for R~5,000 on up to 20 simultaneous targets can be achieved by reformatting the 1 arc-second wide slits into three 0.3 arc-second slits projected next to each other in the spatial direction. The second concept under consideration is a highly multiplexed fiber based system utilizing a robotic fiber positioning system at the focal plane containing 700 individual collectors, and a cluster of up to 12 replicated spectrographs with a minimum resolution of R~5,000 over the full pass band. Each collecting element will contain a bundle of 19 fibers coupled to micro-lens arrays that allow for contiguous coverage of targets and adaptation of the f/15 telescope beam to f/3.2 for feeding the fiber system. This report describes the baseline WFOS design, provides an overview of the two trade study concepts, and the process used to down-select between the two options. Also included is a risk assessment regarding the known technical challenges in the selected design concept.

Paper Details

Date Published: 9 July 2018
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Proc. SPIE 10702, Ground-based and Airborne Instrumentation for Astronomy VII, 1070220 (9 July 2018); doi: 10.1117/12.2312283
Show Author Affiliations
Kevin Bundy, Univ. of California, Santa Cruz (United States)
Maureen Savage, Univ. of California, Santa Cruz (United States)
Renate Kupke, Univ. of California, Santa Cruz (United States)
Nicholas MacDonald, Univ. of California, Santa Cruz (United States)
Kyle Westfall, Univ. of California, Santa Cruz (United States)
Matthew Radovan, Univ. of California, Santa Cruz (United States)
Zheng Cai, Univ. of California, Santa Cruz (United States)
Brian Digiorgio, Univ. of California, Santa Cruz (United States)
Richard Dekany, Caltech (United States)
Devika Divakar, Indian Institute of Astrophysics (India)
Jason Fucik, Caltech (United States)
Hangxin Ji, Nanjing Institute of Astronomical Optics & Technology (China)
Satoshi Miyazaki, National Astronomical Observatory of Japan (Japan)
Shinobu Ozaki, National Astronomical Observatory of Japan (Japan)
Andrew Phillips, Univ. of California, Santa Cruz (United States)
Namrata Roy, Univ. of California, Santa Cruz (United States)
Roger Smith, Caltech (United States)
Arun Surya, Indian Institute of Astrophysics (India)
S. Sriram, Indian Institute of Astrophysics (India)
Sivarani Thirupathi, Indian Institute of Astrophysics (India)
Toshihiro Tsuzuki, National Astronomical Observatory of Japan (Japan)


Published in SPIE Proceedings Vol. 10702:
Ground-based and Airborne Instrumentation for Astronomy VII
Christopher J. Evans; Luc Simard; Hideki Takami, Editor(s)

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