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200 papers

Millimetre-VLBI is an important tool in AGN astrophysics, but it is limited by short atmospheric coherence times and poor receiver and antenna performance. We demonstrate a new kind of phase referencing for the VLBA, enabling us to increase…

Astrophysics · Physics 2007-05-23 E. Middelberg , A. L. Roy , R. C. Walker , H. Falcke , T. P. Krichbaum

Since its observation in 2019, the first image of a super-massive black hole using Very Long Baseline Interferometry (VLBI) with an Earth-scale baseline has generated much scientific and public interest, including the possible extension of…

Instrumentation and Methods for Astrophysics · Physics 2026-05-08 Eric Burt , Todd Ely , Geoff Bower , Joe Lazio , Marin Anderson , Sonia Hernandez

The nearby (d=3.6 Mpc) starburst galaxy M82 has been studied for several decades by very long baseline interferometry (VLBI) networks such as e-MERLIN and the European VLBI Network (EVN). The numerous supernova remnants (SNRs), HII regions…

Modern interconnects offer remote direct memory access (RDMA) features. Yet, most applications rely on explicit message passing for communications albeit their unwanted overheads. The MPI-3.0 standard defines a programming interface for…

Distributed, Parallel, and Cluster Computing · Computer Science 2020-07-01 Robert Gerstenberger , Maciej Besta , Torsten Hoefler

Simultaneous observations at multiple frequency bands have the potential to overcome the fundamental limitation imposed by the atmospheric propagation in mm-VLBI observations. The propagation effects place a severe limit in the sensitivity…

Instrumentation and Methods for Astrophysics · Physics 2015-12-23 Maria J. Rioja , Richard Dodson , Taehyun Jung , Bong Won Sohn

The VLTI Spectro Imager (VSI) was proposed as a second-generation instrument of the Very Large Telescope Interferometer providing the ESO community with spectrally-resolved, near-infrared images at angular resolutions down to 1.1…

Five compact radio sources, include 0420-014, 1334-127, 1504-166, 2243-123, and 2345-167, were observed at 5GHz by European VLBI (Very Long Baseline Interferometry) Network (EVN) in June, 1996. The primary purpose of this observation was to…

Astrophysics · Physics 2007-05-23 J. F. Zhou , D. R. Jiang , X. Y. Hong , T. Venturi

A 32 GHz bandwidth VLBI capable correlator and phased array has been designed and deployed at the Smithsonian Astrophysical Observatory's Submillimeter Array (SMA). The SMA Wideband Astronomical ROACH2 Machine (SWARM) integrates two…

We present the first results of the VLBA Imaging and Polarimetry Survey (VIPS), a 5 GHz VLBI survey of 1,127 sources with flat radio spectra. Through automated data reduction and imaging routines, we have produced publicly available I, Q,…

VLBI astrometry allows coordinates of celestial radio sources to be determined with submilliarcsecond accuracy. In particular, with differential VLBI astrometry, the standard errors of relative positions and proper motions can be as small…

Astrophysics · Physics 2007-05-23 Norbert Bartel

In this paper we introduce a software package, the Very Long Baseline Interferometry Network SIMulator (VNSIM), which provides an integrated platform assisting radio astronomers to design the Very Long Baseline Interferometry (VLBI)…

Instrumentation and Methods for Astrophysics · Physics 2019-11-11 Zhen Zhao , Tao An , Baoqiang Lao

We present preliminary results from a VLBI survey at $\lambda=6 $cm of a sample of 35 sources with flux densities of 2 - 100 mJy. These sources were selected from the VLA FIRST survey at $\lambda = 20 $cm, in a 3 degree field around the…

Astrophysics · Physics 2009-10-31 S. T. Garrington , M. A. Garrett , A. Polatidis

The Pulsar Machine II (PuMa II) is the new flexible pulsar processing backend system at the Westerbork Synthesis Radio Telescope (WSRT), specifically designed to take advantage of the upgraded WSRT. The instrument is based on a computer…

Astrophysics · Physics 2017-04-05 Ramesh Karuppusamy , Ben Stappers , Willem van Straten

A patch of sky in the SDSS Stripe 82 was observed at 1.6 GHz with Very Long Baseline Interferometry (VLBI) using the European VLBI Network (EVN). The data were correlated at the EVN software correlator at JIVE (SFXC). There are fifteen…

Astrophysics of Galaxies · Physics 2014-06-19 H. -M. Cao , S. Frey , L. I. Gurvits , J. Yang , X. -Y. Hong , Z. Paragi , A. T. Deller , Ž. Ivezić

In this document we layout a new method to achieve "bona fide" high precision Very-Long-Baseline-Interferometry (VLBI) astrometric measurements of frequency-dependent positions of celestial sources (even) in the high (mm-wavelength)…

Instrumentation and Methods for Astrophysics · Physics 2009-10-08 Richard Dodson , Maria J. Rioja

A PC based high speed silicon microstrip beam telescope consisting of several independent modules is presented. Every module contains an AC-coupled double sided silicon microstrip sensor and a complete set of analog and digital signal…

Instrumentation and Detectors · Physics 2015-06-26 J. Treis , P. Fischer , L. Klingbeil , H. Krueger , N. Wermes , T. Lari

A 20-hour VLBI observation with the NRAO VLBA and GBT in the NOAO Bootes field reaches an rms noise of 9 microJy per beam at 1.4 GHz. Three sources were detected at 10-milliarcsecond resolution within the GBT primary beam of FWHM 8.6',…

Astrophysics · Physics 2007-05-23 M. A. Garrett , J. M. Wrobel , R. Morganti

The Phasor measurement unit (PMU) measurements are mandatory to monitor the power system's voltage stability margin in an online manner. Monitoring is key to the secure operation of the grid. Traditionally, online monitoring of voltage…

Systems and Control · Electrical Eng. & Systems 2024-12-20 Kishan Prudhvi Guddanti , Amarsagar Reddy Ramapuram Matavalam , Yang Weng

The work describes a system for converting VLBI observation data using the algorithms of coherent dedispersion and compensation of two-bit signal sampling. Coherent dedispersion is important for processing pulsar observations to obtain the…

Instrumentation and Methods for Astrophysics · Physics 2023-03-31 Girin I. A. , Likhachev S. F. , Andrianov A. S. , Burgin M. S. , Popov M. V. , Rudnitskiy A. G. , Soglasnov V. A. , Zuga V. A

Black hole imaging challenges the 3rd generation space VLBI, the Very Long Baseline Interferometry, to operate on a 500 GHz band. The coherent integration time needed here is 450 s though the available space oscillators cannot offer more…

Instrumentation and Methods for Astrophysics · Physics 2021-09-20 V. Kudriashov , M. Martin-Neira , E. Lia , J. Michalski , P. Kant , D. Trofimowicz , M. Belloni , P. Jankovic , P. Waller , M. Brandt