Zero-polarization candidate regions for the calibration of wide-field optical polarimeters
Journal article, 2024

Context. The calibration of optical polarimeters relies on the use of stars with negligible polarization (i.e., unpolarized standard stars) for determining the instrumental polarization zero point. For wide-field polarimeters, calibration is often done by imaging the same star over multiple positions in the field of view (FoV), which is a time-consuming process. A more effective technique is to target fields containing multiple standard stars. While this method has been used for fields with highly polarized stars, there are no such sky regions with well measured unpolarized standard stars. Aims. We aim to identify sky regions with tens of stars exhibiting negligible polarization that are suitable for a zero-point calibration of wide-field polarimeters. Methods. We selected stars in regions with extremely low reddening, located at high Galactic latitudes. We targeted four ∼40′ × 40′ fields in the northern and eight in the southern equatorial hemispheres. Observations were carried out at the Skinakas Observatory and the South African Astronomical Observatory. Results. We found two fields in the north and seven in the south characterized by a mean polarization lower than p < 0.1%. Conclusions. At least 9 out of the 12 fields can be used for a zero-point calibration of wide-field polarimeters.

polarization

ISM: general

methods: observational

catalogs

techniques: polarimetric

Author

N. Mandarakas

University of Crete

Foundation for Research and Technology-Hellas (FORTH)

Georgia Virginia Panopoulou

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

V. Pelgrims

Université libre de Bruxelles (ULB)

S. B. Potter

South African Astronomical Observatory

University of Johannesburg

V. Pavlidou

University of Crete

Foundation for Research and Technology-Hellas (FORTH)

A. N. Ramaprakash

California Institute of Technology (Caltech)

Foundation for Research and Technology-Hellas (FORTH)

Inter-University Centre for Astronomy and Astrophysics

Konstantinos Tassis

University of Crete

Foundation for Research and Technology-Hellas (FORTH)

D. Blinov

Foundation for Research and Technology-Hellas (FORTH)

S. Kiehlmann

Foundation for Research and Technology-Hellas (FORTH)

E. Koutsiona

University of Crete

S. Maharana

South African Astronomical Observatory

S. Romanopoulos

Foundation for Research and Technology-Hellas (FORTH)

University of Crete

R. Skalidis

California Institute of Technology (Caltech)

A. Vervelaki

University of Crete

S. E. Clark

Kavli Institute for Particle Astrophysics and Cosmology

Stanford University

J. A. Kypriotakis

University of Crete

Foundation for Research and Technology-Hellas (FORTH)

A. C.S. Readhead

Foundation for Research and Technology-Hellas (FORTH)

California Institute of Technology (Caltech)

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 684 A132

Subject Categories

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

DOI

10.1051/0004-6361/202348099

More information

Latest update

5/30/2024