Abstract

PASIPHAE survey aims to create the first large sky magnetic field and dust cloud tomographic map of the Galactic polar regions using stellar polarimetry and GAIA stellar distances. Two WALOP (Wide-Area Linear Optical Polarimeter) instruments, to be mounted on 1 m class telescopes in South Africa and Greece are currently under development to work as survey instruments for the PASIPHAE program for creating the stellar polarization catalogue. Scheduled for commissioning in 2023, the WALOPs are being designed to operate with the combined capabilities of one-shot four camera linear polarimetry, low polarization systematic (polarimetric accuracy of 0.1%) and a large field of view of 30×30 arcminutes, which in combination will make these unique astronomical instruments. Operating in the SDSS-r broadband and narrowband filters between 500-700 nm, for each exposure, four images of the full field corresponding to polarization angles of 0, 45, 90 and 135 deg will be generated and carrying out differential photometry on these images will yield the linear Stokes parameters. We have developed a complete design and calibration strategy for WALOPs to achieve its technical goals. In this talk, I will present an overview of the instrument design, development, performance modelling and calibration routine for the instruments and their current status.