Results 21 to 30 of about 11,731 (215)
Overview and Status of the International Celestial Reference Frame as Realized by VLBI
Universe, 2022 Accurate measurement of angular positions on the sky requires a well-defined system of reference that is realized with accessible objects. The purpose of this study is to review the international standard realization of such a system, the International ...
Aletha de Witt +3 more
doaj +1 more source
The VLA-COSMOS Survey. II. Source Catalog of the Large Project [PDF]
, 2006 The VLA-COSMOS Large Project is described and its scientific objective is discussed. We present a catalog of ~3600 radio sources found in the 2 deg^2 COSMOS field at 1.4 GHz. The observations in the VLA A and C configuration resulted in a resolution of 1.
Aussel, H. +13 more
core +3 more sources
Masses and Densities of Dwarf Planet Satellites Measured with ALMA
The Planetary Science Journal, 2023 We have used the Atacama Large Millimeter/submillimeter Array to measure precise absolute astrometric positions and detect the astrometric wobble of dwarf planet Orcus and its satellite Vanth over a complete orbit.
Michael E. Brown, Bryan J. Butler
doaj +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
Probing the Heart of Active Narrow-line Seyfert 1 Galaxies with VERA Wideband Polarimetry
The Astrophysical Journal, 2023 We explored the parsec-scale nuclear regions of a sample of radio-loud narrow-line Seyfert 1 galaxies (NLSy1s) using the VLBI Exploration of Radio Astrometry wideband (at a recording rate of 16 Gbps) polarimetry at 22 and 43 GHz.
Mieko Takamura +11 more
doaj +1 more source
VERA monitoring of the radio jet 3C 84 during 2007--2013: detection of non-linear motion [PDF]
, 2018 We present a kinematic study of the subparsec-scale radio jet of the radio galaxy 3C 84/NGC 1275 with the VLBI Exploration of Radio Astrometry (VERA) array at 22 GHz for 80 epochs from 2007 October to 2013 December.
Akiyama, Kazunori +15 more
core +2 more sources
Radio and Optical Astrometry [PDF]
Symposium - International Astronomical Union, 1974 Radio positional measurements have achieved an accuracy as high as that of optical astrometry, with uncertainties no greater than a few hundredths of an arc second in each coordinate. Declinations and relative right ascensions are determined absolutely.
openaire +1 more source
Ray tracing-based delay model for compensating gravitational deformations of VLBI radio telescopes
Journal of Geodetic Science, 2022 The precision and the reliability of very long baseline interferometry (VLBI) depend on several factors. Apart from fabrication discrepancies or meteorological effects, gravity-induced deformations of the receiving unit of VLBI radio telescopes are ...
Lösler Michael +6 more
doaj +1 more source
Radio source structures in VLBI astrometry [PDF]
Symposium - International Astronomical Union, 1988 In astrometry, celestial radio sources with extended structures are useful. An algorithm to correct for structure in VLBI delays and delay rates is developed. The radio source NRAO140 is mapped from data with limited u-v coverage by the hybrid method and the Maximum Entropy procedure.
Patrick Charlot +2 more
openaire +1 more source
Unconstrained Estimation of VLBI Global Observing System Station Coordinates [PDF]
Advances in Geosciences, 2021 The International VLBI Service for Geodesy and Astrometry (IVS) is currently setting up a network of smaller and thus faster radio telescopes observing at broader bandwidths for improved determination of geodetic parameters. However, this new VLBI Global
M. Mikschi +3 more
doaj +1 more source