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Proceedings Paper

A new calculation of LAMOST optical vignetting
Author(s): Shuang Li; Ali Luo; Jianjun Chen; Genrong Liu; Georges Comte
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Paper Abstract

A new method to calculate the optical vignetting of LAMOST (Large Sky Area Muti-Object Fiber Spectroscopic Telescope) is presented. With the pilot survey of LAMOST, it is necessary to have thorough and quantitative estimation and analysis on the observing efficiency which is affected by various factors: the optical system of the telescope and the spectrograph that is vignetting, the focal instrument, and the site condition. The wide field and large pupil of LAMOST fed by a Schmidt reflecting mirror, with a fixed optical axis coinciding with the local polar axis, lead to significant telescope vignetting, caused by the effective light-collecting area of the corrector, the light obstruction of the focal-plate, and the size of the primary mirror. A calculation of the vignetting has been presented by Xue et al. (2007), which considered 4 meter circle limitation and based on ray-tracking. In fact, there is no effect of the 4 meter circle limitation, so that we compute the vignetting again by means of obtaining the ratio of effective projected area of the corrector. All the results are derived by AUTOCAD. Moreover, the vignetting functions and vignetting variations with declination at which the telescope is pointed and the position considered in the focal surface are presented and analysed. Finally, compared with the ray-tracing method to obtain the vignetting before, the validity and availability of the proposed method are illustrated.

Paper Details

Date Published: 25 September 2012
PDF: 6 pages
Proc. SPIE 8449, Modeling, Systems Engineering, and Project Management for Astronomy V, 84491Q (25 September 2012); doi: 10.1117/12.925990
Show Author Affiliations
Shuang Li, National Astronomical Observatories (China)
Ali Luo, National Astronomical Observatories (China)
Jianjun Chen, National Astronomical Observatories (China)
Genrong Liu, Nanjing Astronomical Optics Technology Institute (China)
Georges Comte, Lab. d'Astrophysique de Marseille (France)

Published in SPIE Proceedings Vol. 8449:
Modeling, Systems Engineering, and Project Management for Astronomy V
George Z. Angeli; Philippe Dierickx, Editor(s)

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