Zero-polarization candidate regions

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. 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. We selected stars in regions with extremely low reddening, located at high Galactic latitudes.