Related papers: VLBI for Gravity Probe B. I. Overview

It is known that a fully relativistic integration of the null geodesics of a weak perturbation of flat spacetime leads to a correction of order $v/c$ to the bending angle and time delay due to a gravitational lens in slow motion with small…

Accurate measurement of pulsar distances via astrometry using very long baseline interferometry enables the improvement of Galactic electron density distribution models, improving distance estimates for the vast majority of pulsars for…

The Sun's gravitational field deflects the apparent positions of close objects in accordance with the formulae of general relativity. Optical astrometry is used to test the prediction, but only with the stars close to the Sun and only…

We have made timing observations of binary pulsar PSR B1534+12 with radio telescopes at Arecibo, Green Bank, and Jodrell Bank. By combining our new observations with data collected up to seven years earlier, we obtain a significantly…

We present Global VLBI and HSA images of the gravitational lens B2016+112 at 18, 6 and 3.6 cm. Previous VLBI observations showed that images A and B (which are clearly lensed images of a single background source) and the elongated region C…

PSR J0218$+$4232 is a millisecond pulsar (MSP) with a flux density $\sim$ 0.9 mJy at 1.4 GHz. It is very bright in the high-energy X-ray and $\gamma$-ray domains. We conducted an astrometric program using the European VLBI Network (EVN) at…

We present the first pulsar parallaxes measured with phase-referenced pulsar VLBI observations at 5 GHz. Due to the steep spectra of pulsars, previous astrometric measurements have been at lower frequencies. However, the strongest pulsars…

The detection of astrophysical Gamma-Ray Bursts (GRBs) has always been intertwined with the challenge of identifying the direction of the source. Accurate angular localization of better than a degree has been achieved to date only with…

Experimental verification of the existence of gravimagnetic fields generated by currents of matter is important for a complete understanding and formulation of gravitational physics. Although the rotational `intrinsic' gravimagnetic field…

Model-independent distance constraints to binary millisecond pulsars (MSPs) are of great value to both the timing observations of the radio pulsars, and multiwavelength observations of their companion stars. Very Long Baseline…

We report results of astrometric VLBI observations toward a Mira variable star BX~Cam using the VLBI array "VERA". The observations were performed from February 2012 to November 2014. Obtained parallax is 1.73$\pm$0.03 mas corresponding to…

This paper introduces a new instrument enabling a novel combination of Earth measuring techniques: direct observations with the radio astronomical instruments to satellites of the global navigation satellite systems. Inter-technique biases…

Giant exoplanets have been directly imaged over orders of magnitude of orbital separations, prompting theoretical and observational investigations of their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data of…

We study various measures of weak lensing distortions in future surveys, taking into account the noise arising from the finite survey size and the intrinsic ellipticity of galaxies. We also consider a realistic redshift distribution of the…

A low-amplitude periodic signal in the radial velocity (RV) time series of Barnard's Star was recently attributed to a planetary companion with a minimum mass of ${\sim}$3.2 $M_\oplus$ at an orbital period of $\sim$233 days. The relatively…

We present improved relative astrometry for stars within the central half parsec of our Galactic Center based on data obtained with the 10 m W. M. Keck Observatory from 1995 to 2017. The new methods used to improve the astrometric precision…

Accurate pulsar astrometric estimates play an essential role in almost all high-precision pulsar timing experiments. Traditional pulsar timing techniques refine these estimates by including them as free parameters when fitting a model to…

The accuracy reached in the past few years by Satellite Laser Ranging (SLR) allows for measuring even tiny features of the Earth's gravitational field predicted by Einstein's General Relativity by means of artificial satellites. The…

The Space Interferometry Mission (SIM), with its launch date planned for 2005, has as its goal astrometry with ~ 1 micro-arcsecond accuracy for stars as faint as 20th mag. If the SIM lives to expectations it can be used to measure…

SS Cygni is one of the brightest dwarf novae (DNe), and one of the best-studied prototypes of the cataclysmic variables. Astrometric observations with the Fine Guidance Sensors (FGS) on the Hubble Space Telescope (HST), published in 2004,…