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Proceedings Paper

Gemini planet imager observational calibrations VII: on-sky polarimetric performance of the Gemini planet imager
Author(s): Sloane J. Wiktorowicz; Max Millar-Blanchaer; Marshall D. Perrin; James R. Graham; Michael P. Fitzgerald; Jérôme Maire; Patrick Ingraham; Dmitry Savransky; Bruce A. Macintosh; Sandrine J. Thomas; Jeffrey K. Chilcote; Zachary H. Draper; Inseok Song; Andrew Cardwell; Stephen J. Goodsell; Markus Hartung; Pascale Hibon; Fredrik Rantakyrö; Naru Sadakuni
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Paper Abstract

We present on-sky polarimetric observations with the Gemini Planet Imager (GPI) obtained at straight Cassegrain focus on the Gemini South 8-m telescope. Observations of polarimetric calibrator stars, ranging from nearly un- polarized to strongly polarized, enable determination of the combined telescope and instrumental polarization. We find the conversion of Stokes I to linear and circular instrumental polarization in the instrument frame to be I → (QIP, UIP, PIP, VIP) = (-0.037 ± 0.010%, +0.4338 ± 0.0075%, 0.4354 ± 0.0075%, -6.64 ± 0.56%). Such precise measurement of instrumental polarization enables ~0.1% absolute accuracy in measurements of linear polarization, which together with GPI’s high contrast will allow GPI to explore scattered light from circumstellar disk in unprecedented detail, conduct observations of a range of other astronomical bodies, and potentially even study polarized thermal emission from young exoplanets. Observations of unpolarized standard stars also let us quantify how well GPI's differential polarimetry mode can suppress the stellar PSF halo. We show that GPI polarimetry achieves cancellation of unpolarized starlight by factors of 100-200, reaching the photon noise limit for sensitivity to circumstellar scattered light for all but the smallest separations at which the calibration for instrumental polarization currently sets the limit.

Paper Details

Date Published: 28 July 2014
PDF: 11 pages
Proc. SPIE 9147, Ground-based and Airborne Instrumentation for Astronomy V, 914783 (28 July 2014); doi: 10.1117/12.2056616
Show Author Affiliations
Sloane J. Wiktorowicz, Univ. of California, Santa Cruz (United States)
Max Millar-Blanchaer, Univ. of Toronto (Canada)
Marshall D. Perrin, Space Telescope Science Institute (United States)
James R. Graham, Univ. of California, Berkeley (United States)
Michael P. Fitzgerald, Univ. of California, Los Angeles (United States)
Jérôme Maire, Dunlap Institute for Astronomy and Astrophysics, Univ. of Toronto (Canada)
Patrick Ingraham, Kavli Institute for Particle Astrophysics and Cosmology, Stanford Univ. (United States)
Univ. de Montréal (Canada)
Dmitry Savransky, Cornell Univ. (United States)
Bruce A. Macintosh, Lawrence Livermore National Lab. (United States)
Stanford Univ. (United States)
Sandrine J. Thomas, NASA Ames Research Ctr. (United States)
Jeffrey K. Chilcote, Univ. of California, Los Angeles (United States)
Zachary H. Draper, Univ. of Victoria (Canada)
Inseok Song, Univ. of Georgia (United States)
Andrew Cardwell, Gemini Observatory (Chile)
Stephen J. Goodsell, Gemini Observatory (United States)
Markus Hartung, Gemini Observatory (Chile)
Pascale Hibon, Gemini Observatory (Chile)
Fredrik Rantakyrö, Gemini Observatory (Chile)
Naru Sadakuni, Gemini Observatory (Chile)

Published in SPIE Proceedings Vol. 9147:
Ground-based and Airborne Instrumentation for Astronomy V
Suzanne K. Ramsay; Ian S. McLean; Hideki Takami, Editor(s)

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