Related papers: VLBI for Gravity Probe B. I. Overview
We use a Chandra X-ray observation of the gravitationally lensed system MGB2016+112 at z=3.273 to elucidate presence of at least two X-ray sources. We find that these sources are consistent with the VLBI components measured by…
High precision astrometric Space Very Long Baseline Interferometry (S-VLBI) at the low end of the conventional frequency range, i.e. 20cm, is a requirement for a number of high priority science goals. These are headlined by obtaining…
We observed VB 10 in August and September 2009 using the FORS2 camera of the VLT with the aim of measuring its astrometric motion and of probing the presence of the announced planet VB 10b. We used the published STEPS astrometric positions…
Measuring the proper motions and geometric distances of galaxies within the Local Group is very important for our understanding of the history, present state and future of the Local Group. Currently, proper motion measurements using optical…
We present updated analyses of pulse profiles and their arrival-times from PSR B1534+12, a 37.9-ms radio pulsar in orbit with another neutron star. A high-precision timing model is derived from twenty-two years of timing data, and accounts…
We report spectroscopic observations of the nearby, 19.5 yr binary system Gls 67 AB spanning more than 35 yr. We carry out a global orbital solution combining our radial velocity measurements with others from the literature going back more…
Understanding the orbits of giant planets is critical for testing planet formation models, particularly at wide separations greater than 10 au where traditional core accretion becomes inefficient. However, constraining orbits at these…
We study the impact of relativistic gravitational deflection of light on the accuracy of future Space Interferometry Mission (SIM). We estimate the deflection angles caused by the monopole, quadrupole and octupole components of…
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…
A relativistic sub-picosecond model of gravitational time delay in radio astronomical observations is worked out and a new experimental test of general relativity is discussed in which the effect of retardation of gravity associated with…
Optical photometry is presented for the quadruple gravitational lens PG1115+080. A preliminary reduction of data taken from November 1995 to June 1996 gives component ``C'' leading component ``B'' by 23.7+/-3.4 days and components ``A1''…
We report the results of VLBI observations of H$_{2}$O masers in the IRAS 20143+3634 star forming region using VERA (VLBI Exploration of Radio Astronomy). By tracking masers for a period of over two years we measured a trigonometric…
Gl 758 B is a late-T dwarf orbiting a metal-rich Sun-like star at a projected separation of $\rho$ $\approx$ 1.6" (25 AU). We present four epochs of astrometry of this system with NIRC2 at Keck Observatory spanning 2010 to 2017 together…
In recent years, radio interferometric observations have achieved high accuracy in determining the absolute values of trigonometric parallaxes and proper motions of maser radiation sources and radio stars. The error in determining the…
In this paper we investigate the possibility of measuring the general relativistic gravitoelectric contribution P^(GE) to the orbital period P of the transiting exoplanet HD 209458b 'Osiris'. It turns out that the predicted magnitude of…
Geodetic Very Long Baseline Interferometry (VLBI) data are capable of measuring the light deflection caused by the gravitational field of the Sun and large planets with high accuracy. The parameter $\gamma$ of the parametrized…
We review the derivation of the metric for a spinning body of any shape and composition using linearized general relativity theory, and also obtain the same metric using a transformation argument. The latter derivation makes it clear that…
Astrometric Very Long Baseline Interferometry (VLBI) observations of maser sources in the Milky Way are used to map the spiral structure of our Galaxy and to determine fundamental parameters such as the rotation velocity ($\Theta_0$) and…
We consider the gravity assist maneuver, that is, a correction of spacecraft motion at its passing near a planet, as a tool for evaluating the Eddington post-Newtonian parameters $\beta$ and $\gamma$, characterizing vacuum spherically…
Joint gravitational-wave (GW) and $\gamma$-ray burst (GRB) observations are among the best prospects for standard siren cosmology. However, the strong selection effect for the coincident GRB detection, which is possible only for sources…