6533b873fe1ef96bd12d587a

RESEARCH PRODUCT

Polarization calibration techniques for the new-generation VLBI

P. De VicenteAlejandro MusIvan Marti-vidalMichael JanssenMichael JanssenJ. González

subject

AstrofísicaAstronomyAstrophysics::High Energy Astrophysical PhenomenaPolarimetryFOS: Physical sciencesAstrophysicsAstrophysics::Cosmology and Extragalactic Astrophysics01 natural sciencesRadio spectrumInstantaneous bandwidthSoftware0103 physical sciencesVery-long-baseline interferometry010303 astronomy & astrophysicsInstrumentation and Methods for Astrophysics (astro-ph.IM)Astrophysics::Galaxy AstrophysicsRemote sensingPhysicsEvent Horizon Telescope010308 nuclear & particles physicsbusiness.industryAstrophysics::Instrumentation and Methods for AstrophysicsAstronomy and AstrophysicsPolarization (waves)Nonlinear systemSpace and Planetary ScienceAstronomiabusinessAstrophysics - Instrumentation and Methods for Astrophysics

description

The calibration and analysis of polarization observations in Very Long Baseline Interferometry (VLBI) requires the use of specific algorithms that suffer from several limitations, closely related to assumptions in the data properties that may not hold in observations taken with new-generation VLBI equipment. Nowadays, the instantaneous bandwidth achievable with VLBI backends can be as high as several GHz, covering several radio bands simultaneously. In addition, the sensitivity of VLBI observations with state-of-the-art equipment may reach dynamic ranges of tens of thousands, both in total intensity and in polarization. In this paper, we discuss the impact of the limitations of common VLBI polarimetry algorithms on narrow-field observations taken with modern VLBI arrays (from the VLBI Global Observing System, VGOS, to the Event Horizon Telescope, EHT) and present new software that overcomes these limitations. In particular, our software is able to perform a simultaneous fit of multiple calibrator sources, include non-linear terms in the model of the instrumental polarization and use a self-calibration approach for the estimate of the polarization leakage in the antenna receivers.

yearjournalcountryeditionlanguage
2020-12-10
10.1051/0004-6361/202039527https://doi.org/10.1051/0004-6361/202039527