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Galaxies 2016, 4(4), 55; doi:10.3390/galaxies4040055

The RadioAstron Dedicated DiFX Distribution

1
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2
Deutsches GeoForschungsZentrum GFZ, Telegrafenberg A6, 14473 Potsdam, Germany
3
Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
*
Author to whom correspondence should be addressed.
Academic Editors: Jose L. Gómez, Alan P. Marscher and Svetlana G. Jorstad
Received: 18 July 2016 / Revised: 16 October 2016 / Accepted: 17 October 2016 / Published: 27 October 2016
(This article belongs to the Special Issue Blazars through Sharp Multi-wavelength Eyes)
View Full-Text   |   Download PDF [262 KB, uploaded 27 October 2016]   |  

Abstract

Distributed FX-architecture (DiFX) is a software Very Long Baseline Interferometry (VLBI) correlator currently adopted by several main correlation sites around the globe. After the launch of the RadioAstron Space-VLBI mission in 2011, an extension was necessary to handle processing of an orbiting antenna, to be correlated with supporting ground arrays. Here, we present a branch of the main DiFX distribution (2.4), uploaded on the publicly available repository during July 2016, that the Max Planck Institute for Radio Astronomy (MPIfR) developed to process data of the three key active galactic nuclei (AGN)-imaging RadioAstron science projects, as well as part of the AGN survey project, and General Observing Time (GOT) projects proposed since Announcement of Opportunity 2 (AO-2, July 2014–July 2015). It can account for general relativistic correction of an orbiting antenna with variable position/velocity, providing a routine to convert the native RadioAstron Data Format (RDF) format to the more common Mark5 B (M5B). The possibility of introducing a polynomial clock allows one to mitigate the effects of spacecraft acceleration terms in near-perigee observations. Additionally, since for the first time polarimetry on space-baselines is available thanks to RadioAstron, this DiFX branch allows one to include the spacecraft orientation information at the correlation stage, in order to perform proper polarization calibration during data reduction. Finally, a fringe-finding algorithm able to manage an arbitrarily large fringe-search window is included, allowing one to increase the search space normally adopted by common software packages like HOPS. View Full-Text
Keywords: VLBI; space-VLBI; correlation; RadioAstron; AGN VLBI; space-VLBI; correlation; RadioAstron; AGN
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Bruni, G.; Anderson, J.M.; Alef, W.; Rottmann, H.; Lobanov, A.P.; Zensus, J.A. The RadioAstron Dedicated DiFX Distribution. Galaxies 2016, 4, 55.

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