YFPOL: A Linear Polarimeter of Lijiang 2.4 m Telescope
YFPOL: A Linear Polarimeter of Lijiang 2.4 m Telescope作者机构：Yunnan ObservatoriesChinese Academy of SciencesKunming 650216China University of Chinese Academy of SciencesBeijing 100049China Key Laboratory for the Structure and Evolution of Celestial ObjectsChinese Academy of SciencesKunming 650216China Center for Astronomical Mega-ScienceChinese Academy of SciencesBeijing 100012China
出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)
年 卷 期：2022年第22卷第9期
页 面：10-34页
核心收录：
学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学]
基 金：supported by the National Key R&D Program of China with No.2021YFA1600404 the National Natural Science Foundation of China (NSFC, Grant Nos. 11991051, 11573067, 11673062,11527804, U1931206 and 11873091) the CAS “Light of West China” Program the Yunnan Province Basic Research Plan with No. 2019FA001 the China Manned Space Project with No. CMS-CSST-2021-A06 funded by Yunnan Province,Chinese Academy of Sciences and NSFC
主 题：polarization instrumentation:polarimeters techniques:image processing techniques:polarimetric
摘 要：Polarimetry plays an important role in investigating physical properties for celestial objects. We present a polarimeter named YFPOL for the Cassegrain focus of the Lijiang 2.4 m Telescope(LJT) of Yunnan Observatories, Chinese Academy of Sciences. YFPOL is a traditional single-beam polarimeter with a rotating polarizer. As the focal-reducer instrument Yunnan Faint Object Spectrograph and Camera(YFOSC) is always positioned on the Cassegrain focal plane of LJT, we develop two sets of ultra-thin(thickness 12 mm) polarizer rotation control systems with wireless charging and control functions, which are suitable for mounting on the two front-wheels of YFOSC. One set is used as the polarimetric calibration unit, and the other is for the polarimetric modulation unit. Both of the polarizers have an ultra-high contrast ratio of 1,000,000:1 in the optical band. We investigate the instrumental polarization characteristics(IPCs) in the full field of view that is transferred from YFOSC. Furthermore, we identify that the IPCs change when the Cassegrain axis rotates. The spurious polarization from the IPCs can be effectively minimized by flat-fielding using the unpolarized domeflat, when the Cassegrain rotation angle is the same or nearest to that of the polarization observation. We develop a quasiautomatic pipeline for YFPOL and its effectiveness has been verified by tests of the polarimetric observation with blazar S5 0716+714. The calibration is performed by observing the zero-polarized and highly-polarized standard stars. We successfully reach high precision polarization in the 7’ field of view, and the systematic uncertainty is below 0.8% for a V = 11.68 target with a 10 s exposure. The instrument polarization angle offset is 2°. 6. YFPOL is not only a simple polarimeter, but also a spectropolarimeter with grisms that can be considered in the future.
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