Related papers: Techniques for Measuring Parallax and Proper Motio…
We determined the distances to nine pulsars by parallax measurements using the NRAO Very Long Baseline Array, doubling the number of pulsars with accurate distance measurements. Broadband phase modeling was used to calibrate the varying…
Determination of pulsar parallaxes and proper motions addresses fundamental astrophysical questions. We have recently finished a VLBI astrometry project to determine the proper motions and parallaxes of 27 pulsars, thereby doubling the…
The extraordinary astrometric accuracy of radio interferometry creates an important and unique opportunity for the discovery and characterization of exo-planets. Currently, the Very Long Baseline Array can routinely achieve better than 100…
The Caltech-Jodrell Bank very long baseline interferometry (VLBI) Surveys give detailed 5 GHz VLBI images of several hundred milliarcsecond (mas) radio sources, and the full width at half-maximum angular sizes of the corresponding compact…
We discuss the technique of Wide-field imaging as it applies to Very Long Baseline Interferometry (VLBI). In the past VLBI data sets were usually averaged so severely that the field-of-view was typically restricted to regions extending a…
Planetary ephemerides have been developed and improved over centuries. They are a fundamental tool for understanding solar system dynamics, and essential for planetary and small body mass determinations, occultation predictions,…
We report on recent technical developments in the front- and back-ends for the four 20 m radio telescopes of the Japanese Very-Long-Baseline Interferometry (VLBI) project, VLBI Exploration of Radio Astrometry (VERA). We present a brief…
We describe a data reduction pipeline for VLBI astrometric observations of pulsars, implemented using the ParselTongue AIPS interface. The pipeline performs calibration (including ionosphere modeling), phase referencing with proper…
(Abridged) This thesis describes the development of DiFX, the first general-purpose software correlator for radio interferometry, and its use with the Australian Long Baseline Array (LBA) to complete the largest VLBI pulsar astrometry…
We show that distances of objects at cosmological distances can be measured directly using interferometry. Our approach to interferometric parallax comes from analysis of 4-point amplitude and intensity correlations that can be generated…
We use VLBI imaging of the interstellar scattering speckle pattern associated with the pulsar PSR 0834+06 to measure the astrometric motion of its emission. The ~ 5AU interstellar baselines, provided by interference between speckles…
We present the results of several multi-station Very Long Baseline Interferometry (VLBI) experiments conducted with the ESA spacecraft Venus Express as a target. To determine the true capabilities of VLBI tracking for future planetary…
We use the multi-epoch K$\rm _S$ band observations, covering a $\sim$5 years baseline to obtain milli and sub-milli arcsec precision astrometry for a sample of eighteen previously known high proper motion sources, including precise…
In this paper we describe a new approach for mm-VLBI calibration that provides bona-fide astrometric alignment of the mm-wavelength images from a single source, for the measurement of frequency dependent effects, such as `core-shifts' near…
The circumstellar masers around evolved stars offer an interesting possibility to measure stellar parameters through VLBI astrometry. In this paper the application of this technique is discussed, including the accuracy and the uncertainties…
For Very Long Baseline Interferometry (VLBI), the fringe spacing is extremely narrow compared to the field of view imposed by the primary beam of each element. This means that an extremely large number of resolution units can potentially be…
Radio observations using the Very Long Baseline Interferometry (VLBI) technique typically have fields of view of only a few arcseconds, due to the computational problems inherent in imaging larger fields. Furthermore, sensitivity…
Interferometers require accurate determination of the array configuration in order to produce reliable observations. A method is presented for finding the maximum-likelihood estimate of the telescope geometry, and of other instrumental…
The conventional approach to high-precision narrow-angle astrometry using a long baseline interferometer is to directly measure the fringe packet separation of a target and a nearby reference star. This is done by means of a technique known…
Astrometry can bring powerful constraints to bear on a variety of scientific questions about neutron stars, including their origins, astrophysics, evolution, and environments. Using phase-referenced observations at the VLBA, in conjunction…