CaltechAUTHORS
Published July 2022 | Version public
Journal Article Metadata-only

WALOP-South: a four-camera one-shot imaging polarimeter for PASIPHAE survey. Paper II – polarimetric modeling and calibration

Creators

  • 1. ROR icon Inter-University Centre for Astronomy and Astrophysics
  • 2. ROR icon University of Arizona
  • 3. ROR icon FORTH Institute of Astrophysics
  • 4. ROR icon California Institute of Technology
  • 5. ROR icon University of Oslo
  • 6. ROR icon University of Crete
  • 7. ROR icon National Institute of Science Education and Research
  • 8. ROR icon South African Radio Astronomy Observatory
  • 9. ROR icon University of Johannesburg

Abstract

The Wide-Area Linear Optical Polarimeter (WALOP)-South instrument is an upcoming wide-field and high accuracy optical polarimeter to be used as a survey instrument for carrying out the Polar-Areas Stellar Imaging in Polarization High-Accuracy Experiment program. Designed to operate as a one-shot four-channel and four-camera imaging polarimeter, it will have a field of view of 35 × 35 arcminutes and will measure the Stokes parameters l, q, and u in a single exposure in the Sloan Digital Sky Survey-r broadband filter. The design goal for the instrument is to achieve an overall polarimetric measurement accuracy of 0.1% over the entire field of view. We present here the complete polarimetric modeling of the instrument, characterizing the amount and sources of instrumental polarization. To accurately retrieve the real Stokes parameters of a source from the measured values, we have developed a calibration method for the instrument. Using this calibration method and simulated data, we demonstrate how to correct for instrumental polarization and obtain 0.1% accuracy in degree of polarization, p. In addition, we tested and validated the calibration method by implementing it on a table-top WALOP like test-bed polarimeter in the laboratory.

Additional Information

© 2022 Society of Photo-Optical Instrumentation Engineers. The PASIPHAE program is supported by grants from the European Research Council (ERC) under Grant Agreement Nos. 771282 and 772253; by the National Science Foundation (NSF) award AST-2109127; by the National Research Foundation of South Africa under the National Equipment Programme; by the Stavros Niarchos Foundation under grant PASIPHAE; and by the Infosys Foundation. This work utilized the open-source software packages Astropy, Numpy, Scipy, Matplotlib, and Jupyter notebook. We are thankful to Vinod Vats at Karl Lambrecht Corp. for his inputs and suggestions on various aspects of half-wave plate design and performance.

Additional details

Identifiers

Eprint ID
117542
Resolver ID
CaltechAUTHORS:20221024-123751900.11

Funding

European Research Council (ERC)
771282
European Research Council (ERC)
772253
NSF
AST-2109127
National Research Foundation (South Africa)
Stavros Niarchos Foundation
Infosys Foundation

Dates

Created
2022-10-28
Created from EPrint's datestamp field
Updated
2023-07-10
Created from EPrint's last_modified field

Caltech Custom Metadata

Caltech groups
Astronomy Department