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Proceedings Paper

Observational aspects in multi-object fiber spectroscopy
Author(s): Jean Gabriel Cuby
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Paper Abstract

The scientific objectives of multi-object fiber instruments on 8 m class telescopes may significantly depart from those carried out on 4 m class telescopes. Crude anticipation of future programs on these instruments allows to predict that targets will be mainly point sources or of low extension, with magnitudes up to approximately 22. With these characteristics, some observational aspects are investigated: (1) The (blind) positioning error budget constrains the astrometry to within 0.2' rms to keep photon losses at an acceptable level; (2) All-sky atlases from Schmidt plate scans, when available, will provide the relevant information for most programs; (3) Cross- identification or special observing procedures may be required for guide stars if they have a different origin than targets; (4) Atmospheric effects are investigated. Chromatic dispersion is shown impossible to calibrate out. The observation wavelength must be properly related to the acquisition and guiding wavelengths, constraining the use of filters; (5) Other observational constraints like sky subtraction or high spectral stability can lead to specific observational procedures. General observing modes are briefly reviewed. The impacts on the performances, described in terms of `Realizable Multiplex Advantage' (RMA) is described. At best, the RMA can reach one third of the number of fibers.

Paper Details

Date Published: 1 June 1994
PDF: 19 pages
Proc. SPIE 2198, Instrumentation in Astronomy VIII, (1 June 1994); doi: 10.1117/12.176680
Show Author Affiliations
Jean Gabriel Cuby, Observatoire de Paris-Meudon (Chile)

Published in SPIE Proceedings Vol. 2198:
Instrumentation in Astronomy VIII
David L. Crawford; Eric R. Craine, Editor(s)

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