14 February 2003 High-resolution spectropolarimetry at the Italian Telescopio Nazionale Galileo
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The polarimeter built for the high resolution spectrograph (SARG) of the alto-azimuthal Telescopio Nazionale Galileo is presented. This double-beam instrument, able to take into account time independent (instrumental) and time dependent (sky transparence) sensitivity, is based on a Fresnel prism (λ/2) and K-prism (λ/4) which gives an almost constant retard along the very large wavelength interval covered with new spectrographs: SARG covers the 370 - 1020 nm range and more than 300 nm in a single exposure. The two flat metallic mirrors, which are necessary to feed the spectrograph, and the alto-azimuthal mounting of the telescope are responsible of an instrumental polarisation depending on the sky position of the target. A modelling of the instrumental polarisation and a hardware correction of the sky rotation are performed to measure the polarisation across stellar-like object at R=115,000 resolution.
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Franco Leone, Franco Leone, Pietro Bruno, Pietro Bruno, Antonio Cali, Antonio Cali, Riccardo Claudi, Riccardo Claudi, Rosario Cosentino, Rosario Cosentino, Giovanni Gentile, Giovanni Gentile, Raffaele Gratton, Raffaele Gratton, Salvatore Scuderi, Salvatore Scuderi, } "High-resolution spectropolarimetry at the Italian Telescopio Nazionale Galileo", Proc. SPIE 4843, Polarimetry in Astronomy, (14 February 2003); doi: 10.1117/12.458623; https://doi.org/10.1117/12.458623

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