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Proceedings Paper

A scheme of flat-fielding for LAMOST
Author(s): Huoming Shi; Gang Wang
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Paper Abstract

Flat-fielding is one of the most important data calibration procedures for wide-field multi-fiber spectroscopy of LAMOST (the Large Sky Area Multi-Object Fiber Spectroscopic Telescope). LAMOST’s unique optical design, wide field of view, significant telescope vignetting and unconventional enclosure structure present a challenge to its flat-fielding method. On the other hand, the spectrographs with its CCD detectors are well fixed on the ground, which implies that there is almost no flexure during spectroscopic observation and thus provides a favorable factor in flat-fielding. Taking into account generally-accepted principles for wide-field multi-fiber spectroscopy and the specific features of LAMOST, a scheme of flat-fielding is designed. It utilizes a combination of the multi-fiber lamp flat field and the offset sky flat field to calibrate all known telescopic and instrumental response ununiformity. The lamp flat field will be used to calibrate the CCD pixel-to-pixel sensitivity variation, fiber transmission as a function of wavelength, and possible spectrographic vignetting. Fiber-to-fiber throughput difference and telescopic vignetting will be corrected with the offset sky flat field. A few choices are proposed for the flat field equipment. The flat-division is described in the context of the data reduction pipeline.

Paper Details

Date Published: 16 September 2004
PDF: 8 pages
Proc. SPIE 5493, Optimizing Scientific Return for Astronomy through Information Technologies, (16 September 2004); doi: 10.1117/12.548014
Show Author Affiliations
Huoming Shi, National Astronomical Observatories (China)
Gang Wang, National Astronomical Observatories (China)

Published in SPIE Proceedings Vol. 5493:
Optimizing Scientific Return for Astronomy through Information Technologies
Peter J. Quinn; Alan Bridger, Editor(s)

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