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Calibration system for the 4MOST multi object fiber-fed spectrographs
Author(s): Ronald Roelfsema; Johan Pragt; Rik ter Horst; Tibor Agocs; Olga Bellido; Joar Brynnel; Ariadna Calcines-Rosario; Steffen Frey; Amina Helmi; Jeroen Herrewijnen; Tom Houtsma; Roelof de Jong; Michael Lehmitz; Graham Murray; Gert Musters; Ramon Navarro; Allar Saviauk; Olivier Schnurr; Ray Sharples; Roland Winkler
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Paper Abstract

A novel concept for the calibration of multi object fiber-fed spectrographs is described for the 4MOST instrument. The 4MOST facility is foreseen to start science operations in 2022 at the ESO VISTA telescope. The calibration system provides intensity, wavelength and resolution calibrations for the 4MOST spectrographs. The heart of the system is a combination of a bright broad band lamp and a Fabry-Perot etalon. The lamp is able to provide sufficient flux to illuminate the VISTA focal plane and the Fabry-Perot etalon provides a regular comb of spectral lines. The Fabry-Perot etalon can be moved in and out of the optical beam to choose between intensity and spectral calibrations. A fiber bundle of 156 fibers is guided to the VISTA spider arms where each fiber is connected to a small integrating sphere. The integrating spheres are attached to the bottom side of the four VISTA telescope spider struts and provide unvignetted illumination of the telescope. The exit port of the integrating spheres is projected on the VISTA focal plane with a small collimator lens. The integrating spheres assure a uniform illumination of the focal plane and are insensitive to FRD effects of the input fibers due to motion and stress during telescope movements. The calibration system illumination only originates from the telescope spiders and therefore the telescope pupil is not fully filled. The calibration system uses the azimuthal scrambling properties of the fibers that connect the telescope focal plane and the spectrometers to completely fill the spectrograph pupil.

Paper Details

Date Published: 10 July 2018
PDF: 17 pages
Proc. SPIE 10702, Ground-based and Airborne Instrumentation for Astronomy VII, 107027V (10 July 2018); doi: 10.1117/12.2312473
Show Author Affiliations
Ronald Roelfsema, NOVA Optical Infrared Instrumentation Group (Netherlands)
Johan Pragt, NOVA Optical Infrared Instrumentation Group (Netherlands)
Rik ter Horst, NOVA Optical Infrared Instrumentation Group (Netherlands)
Tibor Agocs, NOVA Optical Infrared Instrumentation Group (Netherlands)
Olga Bellido, Leibniz-Institut für Astrophysik Potsdam (Germany)
Joar Brynnel, Leibniz-Institut für Astrophysik Potsdam (Germany)
Ariadna Calcines-Rosario, Univ. of Durham (United Kingdom)
Steffen Frey, Leibniz-Institut für Astrophysik Potsdam (Germany)
Amina Helmi, Univ. of Groningen (Netherlands)
Jeroen Herrewijnen, NOVA Optical Infrared Instrumentation Group (Netherlands)
Tom Houtsma, NOVA Optical Infrared Instrumentation Group (Netherlands)
Roelof de Jong, Leibniz-Institut für Astrophysik Potsdam (Germany)
Michael Lehmitz, Max-Planck-Institut für Astronomie (Germany)
Graham Murray, Univ. of Durham (United Kingdom)
Gert Musters, NOVA Optical Infrared Instrumentation Group (Netherlands)
Ramon Navarro, NOVA Optical Infrared Instrumentation Group (Netherlands)
Allar Saviauk, Leibniz-Institut für Astrophysik Potsdam (Germany)
Olivier Schnurr, Leibniz-Institut für Astrophysik Potsdam (Germany)
Ray Sharples, Univ. of Durham (United Kingdom)
Roland Winkler, Leibniz-Institut für Astrophysik Potsdam (Germany)

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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