0000000000408993

AUTHOR

James M. Anderson

showing 3 related works from this author

Geodetic data analysis of VGOS experiments

2021

Very Long Baseline Interferometry (VLBI) serves as one of the common geodetic methods to define the global reference frames and monitor Earth's orientation variations. The technical upgrade of the VLBI method known as the VLBI Global Observing System (VGOS) includes a critical re-design of the observed frequencies from the dual band mode (S and X band, i.e. 2 GHz and 8 GHz) to observations in a broadband (2 – 14 GHz). Since 2019 the first VGOS experiments are available for the geodetic analysis in free access at the International VLBI service for Geodesy and Astrometry (IVS). Also regional-only subnetworks such as European VLBI stations have succeeded already in VGOS mode. Based on these br…

UpgradeVery-long-baseline interferometryBroadbandMode (statistics)X bandGeodetic datumAstrometryGeodesyGeologyReference frame2021 XXXIVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)
researchProduct

RadioAstron reveals a spine-sheath jet structure in 3C 273

2021

We present Space-VLBI RadioAstron observations at 1.6 GHz and 4.8 GHz of the flat spectrum radio quasar 3C 273, with detections on baselines up to 4.5 and 3.3 Earth Diameters, respectively. Achieving the best angular resolution at 1.6 GHz to date, we have imaged limb-brightening in the jet, not previously detected in this source. In contrast, at 4.8 GHz, we detected emission from a central stream of plasma, with a spatial distribution complementary to the limb-brightened emission, indicating an origin in the spine of the jet. While a stratification across the jet width in the flow density, internal energy, magnetic field, or bulk flow velocity are usually invoked to explain the limb-brighte…

Astrophysics::High Energy Astrophysical PhenomenaStratification (water)FOS: Physical sciencesJets [Galaxies]AstrophysicsAstrophysics::Cosmology and Extragalactic Astrophysics01 natural sciencesQuasars: individual: 3C 2730103 physical sciencesAngular resolution010303 astronomy & astrophysicsAstrophysics::Galaxy AstrophysicsPhysicsJet (fluid)Internal energy010308 nuclear & particles physicsAstronomy and AstrophysicsQuasarPlasmaGalaxies: activeAstrophysics - Astrophysics of GalaxiesActive [Galaxies]Magnetic fieldFlow velocitySpace and Planetary ScienceGalaxies: jetsAstrophysics of Galaxies (astro-ph.GA)Astrophysics::Earth and Planetary AstrophysicsIndividual: 3C 273 [Quasars]
researchProduct

The Potsdam Open Source Radio Interferometry Tool (PORT)

2021

The Potsdam Open Source Radio Interferometry Tool (PORT) is the very long baseline interferometry (VLBI) analysis software developed and maintained at the GFZ German Research Centre for Geosciences. Chiefly, PORT is tasked with the timely processing of VLBI sessions and post-processing activities supporting the generation of celestial and terrestrial reference frames. In addition, it serves as a framework for research and development within the GFZ's VLBI working group and is part of the tool set employed in educating young researchers. Starting out from VLBI group delays, PORT estimates station and radio sources positions, as well as Earth orientation parameters, tropospheric parameters, a…

Very long baseline interferometry (1769) [Unified Astronomy Thesaurus concepts]media_common.quotation_subjectgeosciences01 natural sciencesFork (software development)German010104 statistics & probabilityAstronomy data analysis (1858)Astrometry (80)The Potsdam Open Source Radio Interferometry ToolVery long baseline interferometry (1769)0103 physical sciences0101 mathematics010303 astronomy & astrophysicsLibrary functionmedia_commonAstronomy and AstrophysicsArt520 Astronomie und zugeordnete WissenschaftenPort (computer networking)language.human_languageOpen source[SDU]Sciences of the Universe [physics]Space and Planetary Sciencevery long baseline interferometrylanguageddc:520Research developmentVLBIPORTHumanities
researchProduct