High time resolution broad-band polarimetry: technique, calibration and standards

TL;DR

This paper presents an improved high time resolution broad-band polarimetry technique, calibration standards, and a new catalogue of polarization data for 98 bright stars, enhancing accuracy and reliability for future astrophysical research.

Contribution

The authors developed a refined data reduction and calibration method using least squares for Stokes parameters, producing a high-precision polarization catalogue for standard stars.

Findings

Determined polarization values for 98 bright stars with improved accuracy.

Identified variable stars unsuitable as polarization standards.

Created a homogeneous, reliable polarization data set for future studies.

Abstract

Regular large-scale polarimetric observations in Crimean astrophysical observatory began in the early 1960s. In 2002 - 2017 the single-channel aperture photometer-polarimeter with a quarter-wave plate at the 2.6-m Shajn mirror telescope (SMT) was used. We accumulated a large homogeneous data set of polarimetric observations of different types of objects that are to be published separately. Correct polarimetric data processing requires high polarization standards and zero-polarization stars. We aim to improve the data reduction and calibration process to obtain further results with highest possible accuracy. High time resolution broad-band (WR, R, V, B, U) polarization observations are made of 98 known standard stars (527 time series with total duration about 184 hours). We determined values of linear and circular polarization for 98 nearby Northern bright stars. This catalogue is not compilative, but obtained using the same instrument and technique during large time interval. It will be used for our future research and it may be used by other authors. We implemented the least squares approach for determination of the Stokes parameters. It allowed us to obtain results with the accuracy better then we obtained using previously used methods. We report suspicious or variable stars that are not suitable as standards for high precision polarimetry.