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Solar rotational tomography (SRT) is an important method to reconstruct the physical parameters of the three-dimensional solar corona. Here we propose an approach to apply the filtered backprojection (FBP) algorithm to the SRT. The FBP…

Solar and Stellar Astrophysics · Physics 2020-06-03 Kyuhyoun Cho , Jongchul Chae , Ryun-Young Kwon , Su-Chan Bong , Kyung-Suk Cho

High-contrast imaging instruments are now being equipped with integral field spectrographs (IFS) to facilitate the detection and characterization of faint substellar companions. Algorithms currently envisioned to handle IFS data, such as…

Polynomial and rational functions are the number one choice when it comes to modeling of radial distortion of lenses. However, several extrapolation and numerical issues may arise while using these functions that have not been covered by…

Optimization and Control · Mathematics 2014-09-22 Jan Heller , Didier Henrion , Tomas Pajdla

We propose a new technique for radio interferometry to obtain super-resolution full polarization images in all four Stokes parameters using sparse modeling. The proposed technique reconstructs the image in each Stokes parameter from the…

This paper is devoted to the primary spectro-polarimetric observation performed at the New Vacuum Solar Telescope of China since 2017, and our aim is to precisely evaluate the real polarimetric accuracy and sensitivity of this polarimetry…

Solar and Stellar Astrophysics · Physics 2020-05-06 Jun-Feng Hou , Zhi Xu , Shu Yuan , Yu-Chao Chen , Jian-Guo Peng , Dong-Guang Wang , Jun Xu , Yuan-Yong Deng , Zhen-Yu Jin , Kai-Fan Ji , Zhong Liu

Imaging Fabry-P\'erot Interferometer (FPI) observations are commonly used in solar physics to infer physical parameters in the photosphere and chromosphere through modeling of the observations. Such techniques require detailed knowledge of…

Instrumentation and Methods for Astrophysics · Physics 2026-05-06 J. de la Cruz Rodríguez , G. B. Scharmer , P. Sütterlin , J. Leenaarts , M. G. Löfdahl , D. Kiselman , T. Hillberg , O. Andriienko

Direction-dependent instrumental polarisation introduces wide-field polarimetric aberrations and limits the dynamic range of low-frequency interferometric images. We therefore provide a detailed two-dimensional analysis of the Giant…

Instrumentation and Methods for Astrophysics · Physics 2014-07-03 J. S. Farnes

The in-flight calibration and performance of the Solar Disk Imager (SDI), which is a pivotal instrument of the Lyman-alpha Solar Telescope (LST) onboard the Advanced Space-based Solar Observatory (ASO-S) mission, suggested a much lower…

Solar and Stellar Astrophysics · Physics 2025-01-03 Hui Liu , Hui Li , Sizhong Zou , Kaifan Ji , Zhenyu Jin , Jiahui Shan , Jingwei Li , Guanglu Shi , Yu Huang , Li Feng , Jianchao Xue , Qiao Li , Dechao Song , Ying Li

The method of solar magnetic field calibration for the filter-based magnetograph is normally the linear calibration method under weak-field approximation that cannot generate the strong magnetic field region well due to the magnetic…

Solar and Stellar Astrophysics · Physics 2021-02-10 Jingjing Guo , Xianyong Bai , Yuanyong Deng , Hui Liu , Jiaben Lin , Jiangtao Su , Xiao Yang , Kaifan Ji

Accurate measurement of polarization in spectral lines is important for the reliable inference of magnetic fields on the Sun. For ground based observations, polarimetric precision is severely limited by the presence of Earth's atmosphere.…

Instrumentation and Detectors · Physics 2012-11-05 K. Nagaraju , Alex Feller

In this paper, we try to improve the magnetogram calibration method of the Solar Magnetic Field Telescope (SMFT). The improved calibration process fits the observed full Stokes information, using six points on the profile of Fe {\i} 5324.18…

Solar and Stellar Astrophysics · Physics 2014-09-18 Xianyong Bai , Yuanyong Deng , Fei Teng , Jiangtao Su , Xinjie Mao , Guoping Wang

We describe a proposal for the optical design of three dual Fabry-Perot based narrowband filter systems for for the future European Solar Telescope (EST). These are intended to constitute the core elements of three imaging…

Instrumentation and Methods for Astrophysics · Physics 2025-05-28 Goran B. Scharmer , Bo Lindberg

We report on a broader evaluation of statistical bootstrap resampling methods as a tool for pixel-level calibration and imaging fidelity assessment in radio interferometry. Pixel-level imaging fidelity assessment is a challenging problem,…

Instrumentation and Methods for Astrophysics · Physics 2015-05-14 Athol Kemball , Adam Martinsek , Modhurita Mitra , Hsin-Fang Chiang

The correction of the influence of phase corrugation in the pupil plane is a fundamental issue in achieving high dynamic range imaging. In this paper, we investigate an instrumental setup which consists in applying interferometric…

Astrophysics · Physics 2008-11-26 S. Lacour , E. Thiébaut , G. Perrin

To study and monitor the Sun and its atmosphere, various space missions have been launched in the past decades. With the rapid improvement in technology and different mission requirements, the data products are subject to constant change.…

We describe techniques concerning wavelength calibration and sky subtraction to maximise the scientific utility of data from tunable filter instruments. While we specifically address data from the Optical System for Imaging and low…

Instrumentation and Methods for Astrophysics · Physics 2015-10-14 Tim Weinzirl , Alfonso Aragon-Salamanca , Steven P. Bamford , Bruno Rodriguez del Pino , Meghan E. Gray , Ana L. Chies-Santos

Polarimetry aims to measure polarization information of an optical field, providing a new freedom to enhance performance of optical metrology. Furthermore, the polarimetry in infrared (IR) range holds a promise for a wide range of academic…

All observations by the aperture photometer (PHT-P) and the far-infrared (FIR) camera section (PHT-C) of ISOPHOT included reference measurements against stable internal fine calibration sources (FCS) to correct for temporal drifts in…

We present a generic algorithm for performing astronomical image registration and pointing refinement. The method is based on matching the positions and fluxes of available point sources in image overlap regions. This information is used to…

Astrophysics · Physics 2009-11-10 Frank J. Masci , David Makovoz , Mehrdad Moshir

The study of the linear and circular polarization in AGN allows one to gain detailed information about the properties of the magnetic fields in these objects. However, especially the observation of circular polarization (CP) with…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 E. Cenacchi , A. Kraus , A. Orfei , K. -H. Mack