Related papers: On the Accuracy of Galileo's Observations
We study the effect of long gradient modes on large scale observables. When defined correctly, genuine observables should not only be gauge invariant but also devoid of any gauge artifacts. One such gauge artifact is a pure gradient mode.…
The theory of measurement is employed to elucidate the physical basis of general relativity. For measurements involving phenomena with intrinsic length or time scales, such scales must in general be negligible compared to the (translational…
Gravitational lensing is now widely and successfully used to study a range of astronomical phenomena, from individual objects, like galaxies and clusters, to the mass distribution on various scales, to the overall geometry of the Universe.…
Gravitational waves propagate along null geodesics like light rays in the geometrical optics approximation, and they may have a chance to suffer from gravitational lensing by intervening objects, as is the case for electromagnetic waves.…
Unusual features of water waves that Galileo described in a letter to Cardinal Orsini in 1616 are revisited from the perspectives of singular optics and geometric analysis.
Large ground-based telescopes equipped with adaptive optics (AO) systems have ushered in a new era of high-resolution infrared photometry and astrometry. Relative astrometric accuracies of <0.2 mas have already been demonstrated from…
A common misconception about laser interferometric detectors of gravitational waves purports that, because the wavelength of laser light and the length of an interferometer's arm are both stretched by a gravitational wave, no effect should…
Observational astrophysics uses sophisticated technology to collect and measure electromagnetic and other radiation from beyond the Earth. Modern observatories produce large, complex datasets and extracting the maximum possible information…
A modified version of the folded aplanatic Gregory telescope equipped with a spherical two-lens corrector is proposed for observations requiring a high signal-to-noise ratio. The basic telescope model has an aperture of 400 mm (f/3.0), its…
Although the formulas for the light deflection due to quadrupole gravitational field of deflecting bodies are well known, the formulas are rather complicated, so that massive computations of quadrupole light deflection (e.g., in the…
We investigate the ability of ground based gravitational wave observatories to detect gravitational wave lensing events caused by stellar mass lenses. We show that LIGO and Virgo possess the sensitivities required to detect lenses with…
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…
A well constrained estimate of the distance remains one of the main factors to properly interpret the observations of accreting X-ray pulsars. Since these objects are typically well studied, multiple distance estimates obtained with…
Context. Astrometric gravitational microlensing can be used to determine the mass of a single star (the lens) with an accuracy of a few percent. To do so, precise measurements of the angular separations between lens and background star with…
Microlensing consists in two major effects: (1) variation in the apparent position of the background sources (astrometric component) and (2) flux variations of the background sources (photometric component). While the latter has been…
SOFIA is an airborne, gyroscopically stabilized 2.5m infrared telescope, mounted to a spherical bearing. Unlike its predecessors, SOFIA will work in absolute coordinates, despite its continually changing position and attitude. In order to…
Johannes Hevelius's 1662 Mercurius in Sole Visus Gedani contains a table of magnitudes and apparent telescopic diameters of nineteen stars. The data conform to a simple model, suggesting that Hevelius produced what is essentially a table of…
Optics is limited in the 'ray-approximation'-inclusion of wave properties result in additional phenomena and applications; interferometers and diffraction gratings are two manifestations of such non-geometric, physical optics. Incidentally,…
The obliquity of the Galilean satellites is small but not yet observed. Studies of cycloidal lineaments and strike-slip fault patterns on Europa suggest that Europa's obliquity is about 1 deg, although theoretical models of the obliquity…
Exactly 500 years ago, Nicolaus Copernicus drew a lattice of lines on a panel above the doorway to his rooms at Olsztyn Castle, then in the Bishopric of Warmia. Although its design has long been regarded as some kind of reflecting vertical…