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Proceedings Paper

A single-shot optical linear polarimeter for asteroid studies
Author(s): C. Pernechele; L. Abe; P. Bendjoya; A. Cellino; G. Massone; J. P. Rivet; P. Tanga
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Paper Abstract

Polarimetric studies of minor Solar System bodies are useful to access physical parameters, such as albedo and diameter, which are both important and difficult to derive by other techniques. Current activities in this field are limited since most instruments adopted in recent observing campaigns involve photomultipliers detectors. These sensors are suitable for observations of objects with fast polarization variations, but usually suffer from low quantum efficiency. This severely limits the number of accessible targets. For asteroids, the polarization evolves slowly enough to allow more sensitive albeit slower detectors (CCD-based polarimeters). However, polarimetric measurement accuracy may be hampered with usual "sequential" polarimeters. Indeed, retarder plate swapping time, readout and exposure time add up. Consequently, the time laps between complementary polarization measurements (some minutes) may be non-negligible in some cases, compared to the evolution time of the polarization parameters. Moreover, polarimetric accuracy may also be limited by airmass variations between complementary exposures. We are developing a new "single-shot" CCD polarimeter based on a "double-Wollaston" configuration already described in literature [9][10]. This allows simultaneous acquisition of the three Stokes parameters I, Q, U without any moving parts. So, the linear polarization degree can be measured accurately, even for targets with fast polarization and/or airmass variations. Presently, the polarization analyzer is in calibration phase, and will be installed soon at the F/12.5 Cassegrain focus of the West telescope at the "Centre Pédagogique Planète et Univers" facility (C2PU, Observatoire de la Côte d'Azur, Plateau de Calern, France).

Paper Details

Date Published: 24 September 2012
PDF: 6 pages
Proc. SPIE 8446, Ground-based and Airborne Instrumentation for Astronomy IV, 84462H (24 September 2012); doi: 10.1117/12.925933
Show Author Affiliations
C. Pernechele, OINAF - sservatorio Astronomico di Padova (Italy)
L. Abe, Lab. Lagrange, CNRS, Univ. de Nice Sophia-Antipolis (France)
P. Bendjoya, Lab. Lagrange, CNRS, Univ. de Nice Sophia-Antipolis (France)
A. Cellino, INAF - Osservatorio Astronomico di Torino (Italy)
G. Massone, INAF - Osservatorio Astronomico di Torino (Italy)
J. P. Rivet, Lab. Lagrange, CNRS, Univ. de Nice Sophia-Antipolis (France)
P. Tanga, INAF - Osservatorio Astronomico di Torino (Italy)

Published in SPIE Proceedings Vol. 8446:
Ground-based and Airborne Instrumentation for Astronomy IV
Ian S. McLean; Suzanne K. Ramsay; Hideki Takami, Editor(s)

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