Related papers: Spherical Trigonometry of the Projected Baseline A…
We have presented the basic mathematical treatment of interferometry in the optical domain. Its applications in astronomical observations using both the single aperture, as well as the diluted apertures are described in detail. We have also…
We provide first the functional analysis background required for reduced order modeling and present the underlying concepts of reduced basis model reduction. The projection-based model reduction framework under affinity assumptions,…
We propose a new instrumental concept for long-baseline optical single-mode interferometry using integrated optics which were developed for telecommunication. Visible and infrared multi-aperture interferometry requires many optical…
We prove that the focal set generated by the reflection of a point source off a translation invariant surface consists of two sets: a curve and a surface. The focal curve lies in the plane orthogonal to the symmetry direction containing the…
The Subarcsecond Telescope And BaLloon Experiment, STABLE, is the fine stage of a guidance system for a high-altitude ballooning platform designed to demonstrate subarcsecond pointing stability, over one minute using relatively dim guide…
The Wide-Field Spectroscopic Telescope (WST) is a concept for a 12-m class seeing-limited telescope providing two concentric fields of view for simultaneous Multi-Object Spectroscopy and Integral Field Spectroscopy. The specified wavelength…
Atmospheric turbulence is a serious problem for ground-based interferometers. It places tight limits on both sensitivity and measurement precision. Phase referencing is a method to overcome these limitations via the use of a bright…
We measure the projected angle on the plane of the sky between adjacent symmetry axes of tens of multipolar planetary nebulae and find that the distribution of these misalignment angles implies a random three-dimensional angle distribution…
We demonstrate that, by combining optical, radio and X-ray observations of a Seyfert, it is possible to provide a direct measurement of the angle $\beta$ between the direction of the radio jet and the normal to the plane of the spiral host…
We replace the familiar Stokes vector by a tensor. This allows us to introduce, for example, polar-coordinate components of the Stokes vector. From the tensor we can derive the skyrmion field for mapping the polarization in structured light…
The displacement of star images by atmospheric refraction observed by an Earth-bound telescope is dominated by a familiar term proportional to the product of the tangent of the zenith angle by the refractivity at the ground. The manuscript…
The parabolic structure of the secondary or conjugate spectra of pulsars is often the result of isolated one-dimensional (or at least highly anisotropic) lenses in the ISM. The curvature of these features contains information about the…
Vector beams are often regarded as non-separable superpositions of spatial and polarization degrees of freedom that satisfy the wave equation. This interpretation ties their polarization structure to their spatial shape. Here, we introduce…
Nulling interferometry has been identified as a competitive technique for the detection of extrasolar planets. The technique consists in combining out-of-phase pairs of telescopes to null effectively the light of a bright star an reveal the…
Physical processes that manifest as tangential vector fields on a sphere are common in geophysical and environmental sciences. These naturally occurring vector fields are often subject to physical constraints, such as being curl-free or…
We geometrically analyze the problem of estimating parameters related to the shape and size of a two-dimensional target object on the plane by using randomly distributed distance sensors whose locations are unknown. Based on the analysis…
A polarity of a projective plane is a map, often assumed to be involutive, mapping a generic point to a generic line and reciprocally. The most classical polarity is the polarity with respect to a conic, but other exist: the harmonic…
For millenia, sailors have used the empirical rule that the elevation angle of Polaris, the North Star, as measured by sextant, quadrant or astrolabe, is approximately equal to latitude. Here, we show using elementary trigonometry that…
Any four mutually tangent spheres in R^3 determine three coincident lines through opposite pairs of tangencies. As a consequence, we define two new triangle centers.
A spherical planetary nebula is described as a geometric model. The nebula itself is considered as a thin-shell which visualized as a boundary of two spacetimes. The inner and outer curvature tensors of the thin-shell are found in order to…