Related papers: Why Halley did not discover proper motion and why …
In a recent article in this journal [G. Sardin, Measure of the absolute speed through the Bradley aberration of light beams on a three-axis frame, Europhys. Lett. 53 (2001) 310], Sardin proposed to use the Bradley aberration of light for…
The satellite missions Hipparcos and Gaia by the European Space Agency will together bring a decrease of astrometric errors by a factor 10000, four orders of magnitude, more than was achieved during the preceding 500 years. This modern…
(abridged) We want to provide further evidence of the origin of the proposed stellar members of Chamaeleon and to identify interlopers from the foreground \epsilon Cha and \eta Cha associations. To this aim, we compile lists of…
We discuss the deflection of light and Shapiro delay under the influence of gravity as described by Schwarzschild metric. We obtain an exact expression based on the coordinate velocity, as first set forth by Einstein, and present a…
We present the first proper motion study of M10 (NGC6254). Absolute proper motions of about 532 stars in the field of the globular cluster M10 were determined with respect to Hipparcos and ACT reference stars. In addition to photographic…
We examine in detail 15 Babylonian observations of lunar appulses and occultations made between 80 and 419 BC for the purpose of setting useful limits on Earth's clock error, as quantified by $\Delta$T, the difference between Terrestrial…
Stellar occultations provide a powerful tool to explore objects of the outer solar system. The Gaia mission now provides milli-arcsec accuracy on the predictions of these events and makes possible observations that were previously…
An observer stationary with respect to comoving coordinates of the expanding universe should find the redshift distribution to be isotropic. However, a peculiar motion of the observer would introduce a dipole anisotropy in the observed…
A collection is made of presently unexplained phenomena within our Solar system and in the universe. These phenomena are (i) the Pioneer anomaly, (ii) the flyby anomaly, (iii) the increase of the Astronomical Unit, (iv) the quadrupole and…
For 100 years since galaxies were found to be flying apart from each other, astronomers have been trying to determine how fast. The expansion, characterized by the Hubble constant, H0, is confused locally by peculiar velocities caused by…
We present results from the search for astrometric accelerations of stars in $\omega$ Centauri using 13 years of regularly-scheduled {\it Hubble Space Telescope} WFC3/UVIS calibration observations in the cluster core. The high-precision…
Astrometric observations of microlensing events were originally proposed to determine the lens proper motion with which the physical parameters of lenses can be better constrained. In this proceeding, we demonstrate that besides this…
A precise ground based telescope system was developed for laser communication experiments with the geostationary satellite ARTEMIS of ESA. Precise tracking of the satellite was realized by using time resolved coordinates of the satellite.…
In the middle of the seventeenth century, Andr\'e Tacquet, S.J. briefly discussed a scientific argument regarding the structure of a Copernican universe, and commented on Galileo Galilei's discussion of that same argument -- Galileo's…
We present proper motion measurements for carbon stars found during the APM Survey for Cool Carbon Stars in the Galactic Halo (Totten & Irwin, 1998). Measurements are obtained using a combination of POSSI, POSSII and UKST survey plates…
The uncertainties which still plague our understanding of the evolution of the light nuclides D, 3He and 4He in the Galaxy are described. Measurements of the local abundance of deuterium range over a factor of 3. The observed dispersion can…
When guns were developed in Europe in the 14th century, the theory of projectile motion was not the one we are familiar with today due to Galileo and Newton but the one taught by Aristotle approximately 1700 years earlier. In addition to…
Astronomers have been using the measured luminosity to estimate the {\em luminous mass} of stars, based on empirically established mass-to-light ratio which seems to be only applicable to a special class of stars---the main-sequence…
We present an analysis of the proper motion of the Andromeda galaxy (M31), based on the Early Third Data Release of the Gaia mission. We use the Gaia photometry to select young blue main sequence stars, and apply several quality cuts to…
In 1859, Le Verrier discovered the mercury perihelion advance anomaly. This anomaly turned out to be the first relativistic-gravity effect observed. During the 141 years to 2000, the precisions of laboratory and space experiments, and…