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The quasi-satellite (QS) phenomenon makes two celestial bodies to fly near each other (Mikkola et al. 2006) and that effect can be used also to make artificial satellites move in tandem. We consider formation flight of two or three…

Earth and Planetary Astrophysics · Physics 2016-02-17 Seppo Mikkola , Claudiu-Lucian Prioroc

A most desirable feature of a standard candle to estimate astronomical distances is robustness against changes in metallicity and age. It is argued that the radii of main sequence stars with spectral types from solar to A0 show predictable…

Astrophysics · Physics 2009-10-31 Carlos Allende Prieto

The six-fold rotational symmetry of photonic crystal fibers has important manifestations in the radiated fields in terms of i) a focusing phenomena at a finite distance from the end-facet and ii) the formation of low-intensity satellite…

Optics · Physics 2007-05-23 Ali Dabirian , Mahmood Akbari , Niels Asger Mortensen

We investigate to what extent correlating the Fourier components at slightly shifted frequencies of the fluctuations of the electric field measured with a one-dimensional antenna array on board of a satellite flying over a plane, allows one…

Instrumentation and Detectors · Physics 2018-03-14 Daniel Braun , Younes Monjid , Bernard Rougé , Yann Kerr

To determine the precise positions of stars in CCD frames, various centering algorithms have been proposed for astrometry. The effective point spread function (ePSF) and the Gaussian centering algorithms are two representative centering…

Instrumentation and Methods for Astrophysics · Physics 2021-12-28 F. R. Lin , Q. Y. Peng , Z. J. Zheng , B. F. Guo , Y. J. Shang

Measuring similarities/dissimilarities between atomic structures is important for the exploration of potential energy landscapes. However, the cell vectors together with the coordinates of the atoms, which are generally used to describe…

The dilation of a Euclidean graph is defined as the ratio of distance in the graph divided by distance in R^d. In this paper we consider the problem of positioning the root of a star such that the dilation of the resulting star is minimal.…

Computational Geometry · Computer Science 2007-06-14 David Eppstein , Kevin A. Wortman

For scientific computations on a digital computer the set of real number is usually approximated by a finite set F of "floating-point" numbers. We compare the numerical accuracy possible with difference choices of F having approximately the…

Numerical Analysis · Computer Science 2010-04-21 Richard P. Brent

Orbital solutions for binary or multiple stellar systems that combine astrometry (e.g., position angles and angular separations) with spectroscopy (radial velocities) have important advantages over astrometric-only or spectroscopic-only…

Astrophysics · Physics 2007-05-23 Guillermo Torres

Finding an optimal match between two different crystal structures underpins many important materials science problems, including describing solid-solid phase transitions, developing models for interface and grain boundary structures. In…

Materials Science · Physics 2020-02-21 Félix Therrien , Peter Graf , Vladan Stevanović

The impact of mega-constellations of satellites in low-Earth orbit during nighttime optical observations is assessed. Orbital geometry is used to calculate the impact of stellar occultations by satellites on the photometry of individual…

Instrumentation and Methods for Astrophysics · Physics 2022-11-09 Paul J. Groot

In this paper we study equidistant subspace codes, i.e. subspace codes with the property that each two distinct codewords have the same distance. We provide an almost complete classification of such codes under the assumption that the…

Information Theory · Computer Science 2015-07-08 Elisa Gorla , Alberto Ravagnani

This paper investigates the accuracy of recently proposed stochastic geometry-based modeling of low earth orbit (LEO) satellite networks. In particular, we use the Wasserstein Distance-inspired method to analyze the distances between…

Networking and Internet Architecture · Computer Science 2022-07-26 Ruibo Wang , Mustafa A. Kishk , Mohamed-Slim Alouini

This paper presents an analytical model for collision probability assessments between de-orbiting or injecting space objects and satellite constellations. Considering the first to be subjected to a continuous tangential acceleration, its…

Instrumentation and Methods for Astrophysics · Physics 2023-05-15 Eduardo Maria Polli , Juan Luis Gonzalo , Camilla Colombo

Although vital for life on Earth, solar activity poses questions and increasing threats to humanity due to the Sun's unknown dynamics, intensified by our dependence on terrestrial and space-based infrastructure. This situation is compounded…

Space Physics · Physics 2025-01-06 Leonidas Askianakis

The primary distance indicators are established in our Galaxy and the Local Group. There are at least four different methods which give good distances: methods using proper motions, RR Lyraes, Cepheid variables, and Type II supernovae.…

Astrophysics · Physics 2009-10-28 Dragan Huterer , Dimitar D. Sasselov , Paul L. Schechter

The motion of satellite constellations similar to GPS and Galileo is numerically simulated and, then, the region where bifurcation (double positioning) occurs is appropriately represented. In the cases of double positioning, the true…

General Relativity and Quantum Cosmology · Physics 2014-04-04 Neus Puchades , Diego Sáez

The design and comparison of satellite-terrestrial routing (STR) and inter-satellite routing (ISR) in low Earth orbit satellite constellations is a widely discussed topic. The signal propagation distance under STR is generally longer than…

Networking and Internet Architecture · Computer Science 2025-01-09 Ruibo Wang , Mustafa A. Kishk , Howard H. Yang , Mohamed-Slim Alouini

The minimum distance of a code is an important concept in information theory. Hence, computing the minimum distance of a code with a minimum computational cost is a crucial process to many problems in this area. In this paper, we present…

Information Theory · Computer Science 2024-05-01 Fernando Hernando , Francisco D. Igual , Gregorio Quintana-Ortí

We present a new method for detecting and correcting systematic errors in the distances to stars when both proper motions and line-of-sight velocities are available. The method, which is applicable for samples of 200 or more stars that have…

Astrophysics of Galaxies · Physics 2015-06-03 Ralph Schoenrich , James Binney , Martin Asplund