Recent observations have allowed the geometry and kinematics of the M87 jet to be tightly constrained. We combine these constraints with historical Very Long Baseline Interferometry (VLBI) results and the theory of synchrotron self-absorbed radio cores in order to investigate the physical properties of the jet. Our results strongly suggest the jet to be dominated by an electron-positron (pair) ...

We report the detection of 6 active galactic nuclei, and also the marginal detection of the galactic center radio source SGRA*, in 215GHz VLBI observations between the IRAM 30m telescope on Pico Veleta and one 15m antenna of the IRAM Plateau de Bure interferometer (∼ 0.3mas fringe spacing). In this (second) 1.4mm VLBI-experiment we find source dependent ratios between the total and correlated f...

Context. Precise determination of dynamical masses of pre-main-sequence (PMS) stars is essential to calibrate stellar evolution models that are widely used to derive theoretical masses of young low-mass objects. Binary stars in young, nearby loose associations are particularly good candidates for this calibration since all members share a common age. Interestingly, some of these young binaries ...

In connection with the work for the next generation VLBI2010 Global Observing System (VGOS) of the International VLBI Service for Geodesy and Astrometry, a new scheduling package (Vie_Sched) has been developed at the Vienna University of Technology as a part of the Vienna VLBI Software. In addition to the classical station-based approach it is equipped with a new scheduling strategy based on th...

In recent years space geodetic techniques such as the Global Positioning System (GPS), Very Long Baseline Interferometry (VLBI), and Satellite Laser Ranging (SLR) have been collocated to address many applications in geoscience. While results from all these techniques are contaminated by various biases and errors, a commonmode signal has been found among the collocated results of GPS, VLBI and S...

After the scientific rationale is given in the introduction the Terms of Reference and the proceeding of IVS Working Group 2 are presented. Then the present status and future goals of all international activities within IVS are described. In particular the current products of IVS are described in terms of accuracy, reliability, frequency of observing sessions, temporal resolution of the paramet...

VLBI observations of the extremely gamma-bright blazar PKS 0528+134 at 8, 22, 43, and 86 GHz reveal a strongly bent one-sided-core jet structure with at least three moving and two apparently stationary jet components. At the highest observing frequencies the brightest and most compact jet component (the VLBI core) is unresolved with an upper limit to its size of approximately 50 microarcsec cor...

Studying transient phenomena with the Very Long Baseline Interferometry (VLBI) technique faces severe difficulties because the turnaround time of the experiments from the observations to the scientific result is rather long. The e-VLBI technique has made it possible to transfer the data from a number of European VLBI Network (EVN) telescopes to the central data processor at JIVE through optical...

In this paper, a new geometry index of Very Long Baseline Interferometry (VLBI) observing networks, the volume of network V , is examined as an indicator of the errors in the Earth orientation parameters (EOP) obtained from VLBI observations. It has been shown that both EOP precision and accuracy can be well described by the power law σ = aV c in a wide range of the network size from domestic t...

We discuss the advantages of an electronically steerable interferometer of a million square meters collecting area operating at cm-wavelengths as a phased array and in conjunction with other antennas in VLBI mode. With a sensitivity to μJy-level flux densities, a brightness temperature limit of TB = 10 4 K, and an expected dynamic range in future VLBI images of better than 10, the impact of SKA...