Results 61 to 70 of about 7,595 (254)
Consolidation of the Gaia catalogue with Chinese Space Station Telescope astrometry
Frontiers in Astronomy and Space Sciences, 2022 The issue of preservation and improvement of the Gaia catalogue throughout the next few decades is addressed. The goal of this study is to evaluate the feasibility of astrometric parameter update, for objects already in the catalogue, by inclusion of new
M. Gai +6 more
doaj +1 more source
Tycho Astrometry and Photometry [PDF]
Symposium - International Astronomical Union, 1986 The HIPPARCOS Star Mappers were designed to determine the satellite attitude by observation of stars with known positions. ESA has now enhanced them so that the continuous photon counts from two photo multipliers with B and V response will be recorded.
openaire +4 more sources
Revisiting the Excitation of Free Core Nutation
Journal of Geophysical Research: Solid Earth, Volume 129, Issue 9, September 2024.Abstract Earth possesses a Poincaré mode called Free Core Nutation (FCN) due to the misalignment of the rotation axes of the mantle and fluid outer core. FCN is the primary signal in the observations of Celestial Pole Offsets (CPO) and maintained by geophysical mechanisms that are yet to be understood. Earlier studies suggested an origin in Atmospheric
Mostafa Kiani Shahvandi +4 more
wiley +1 more source
An Updated View of the Milky Way from Maser Astrometry
Universe, 2022 Astrometric observations of maser sources in the Milky Way, using the Very Long Baseline Interferometry (VLBI) technique, have been exploited to determine the spiral structure of our Galaxy. Several major spiral arms have now been pinpointed in the first
Katharina Immer, Kazi L. J. Rygl
doaj +1 more source
arXiv: Astrophysics, 2005 General relativistic effects in astrophyiscal systems have been detected thanks to accurate astrometric measurements. We outline some keystones of astrometry such as stellar aberration (argument development during the years 1727-1872); Mercury's perihelion precession (1845-1916); solar disk oblateness (1966-2001); relativistic light deflection (1916 ...
openaire +3 more sources
Symposium - International Astronomical Union, 1984 High precision measurements of the celestial coordinates of pulsars are desirable for a number of reasons. If carried out at several epochs, the measurements can yield angular proper motions; together with distance estimates based on dispersion measure, the proper motion of a pulsar reveals two of three components of its space velocity, and ...
Joseph H. Taylor +3 more
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The Effect of Age on the Grouping of Open Clusters: II—Are There Old Binary Clusters?
Universe, 2022 In the present study, we continue testing the Primordial Group hypothesis (Casado 2022), which postulates that only sufficiently young open clusters can be binary or multiple, and old clusters are essentially single.
Juan Casado
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Macho Photometry and Astrometry [PDF]
Symposium - International Astronomical Union, 1995 MACHOs (Massive Astrophysical Compact Halo Objects) have been discovered by their relativistic amplification of light from distant stars as they crossed very near to the line-of-sight. The very few events were detected from more than a billion photometric measurements of millions of stars in the LMC.
Høg, E. +2 more
openaire +3 more sources
Astronomische Nachrichten, Volume 345, Issue 6-7, July-August 2024.Abstract We present James Webb Space Telescope observations of the globular cluster NGC 6397 and use them to extend to infrared wavelengths the characterization of the cluster's entire white dwarf (WD) cooling sequence (CS). The data allows us to probe fundamental astrophysical WD properties and to search for evidence in their colors for (or against ...
L. R. Bedin +11 more
wiley +1 more source
Not So Fast: A New Catalog of Meteor Persistent Trains
Journal of Geophysical Research: Space Physics, Volume 129, Issue 7, July 2024.Abstract This paper presents the results of a nearly 2‐year long campaign to detect and analyze meteor persistent trains (PTs)—self‐emitting phenomena which can linger up to an hour after their parent meteor. The modern understanding of PTs has been primarily developed from the Leonid storms at the turn of the century; our goal was to assess the ...
L. E. Cordonnier +4 more
wiley +1 more source