Giono, G.; Ishikawa, R.; Narukage, N.; Kano, R.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.; Tsuneta, S.; Shimizu, T.; Sakao, T.; Cirtain, J.; Champey, P.; Asensio Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.
Bibliographical reference
Solar Physics, Volume 292, Issue 4, article id. #57, 19 pp.
Description
The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding rocket
instrument designed to measure for the first time the linear
polarization of the hydrogen Lyman-{α} line (121.6 nm). The
instrument was successfully launched on 3 September 2015 and
observations were conducted at the solar disc center and close to the
limb during the five-minutes flight. In this article, the disc center
observations are used to provide an in-flight calibration of the
instrument spurious polarization. The derived in-flight spurious
polarization is consistent with the spurious polarization levels
determined during the pre-flight calibration and a statistical analysis
of the polarization fluctuations from solar origin is conducted to
ensure a 0.014% precision on the spurious polarization. The combination
of the pre-flight and the in-flight polarization calibrations provides a
complete picture of the instrument response matrix, and a proper error
transfer method is used to confirm the achieved polarization accuracy.
As a result, the unprecedented 0.1% polarization accuracy of the
instrument in the vacuum ultraviolet is ensured by the polarization
calibration.
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