Results 21 to 30 of about 165 (125)
Optical and radio astrometry of the galaxy associated with FRB 150418 [PDF]
Monthly Notices of the Royal Astronomical Society: Letters, 2016 Abstract A fading radio source, coincident in time and position with the fast radio burst FRB 150418, has been associated with the galaxy WISE J071634.59−190039.2. Subsequent observations of this galaxy have revealed that it contains a persistent, but variable, radio source. We present e-Multi-Element Radio Linked Interferometer Network,
Bassa, C. G. +12 more
openaire +6 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.
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VLBI Astrometry of Radio-Emitting Stars [PDF]
Symposium - International Astronomical Union, 1995 High-accuracy astrometric VLBI observations of 7 radio stars are presented with applications to the connection between the Hipparcos and VLBI extragalactic reference frames, to the identification of the radio emitting region in the ternary system Algol and the detectabity of Jupiter-size planet orbiting the radio star σ2 CrB.
J.-F. Lestrade +6 more
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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
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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
Science with radio pulsar astrometry [PDF]
Proceedings of the International Astronomical Union, 2012 AbstractHigh precision astrometry on radio pulsars can provide model-independent estimates of their distances and velocities. Such estimates serve to calibrate models of the Galactic electron density distribution, thereby improving distance estimates for the entire pulsar population.
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Improving the Reference Frame by Radio–and Optical Astrometry of Radio Stars [PDF]
International Astronomical Union Colloquium, 1991 AbstractA longterm program of precise radio – and optical astrometry of selected radio stars has been conducted in the last decade by our observatories using the VLA and astrographs on both hemispheres. Positions of 54 stars north of −26 deg. declination including 6 MASER stars have been obtained.
Chr. de Vegt +3 more
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Improving the Accuracy of Radio Astrometry [PDF]
International Astronomical Union Colloquium, 2000 AbstractThe International Celestial Reference Frame (ICRF) is currently realized by the radio positions of compact extragalactic objects obtained by the technique of Very Long Baseline Interferometry (VLBI). The positions of the defining sources with the highest quality are estimated to be accurate at the 0.25 milliarcsecond (mas) level.
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CCD astrometry of faint compact extragalactic radio sources. III. [PDF]
Astronomy & Astrophysics, 2001 Optical positions relative to the Hipparcos Catalogue (ESA 1997) have been obtained for the optical counterparts of 28 faint (B 20 23) southern compact extragalactic radio sources (CERS). Most of these sources are not adequately observable (or simply not visible) by means of direct photography with a conventional wide- eld telescope, so the positions ...
E. Costa, P. Loyola
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The VERA project (VLBI Exploration of Radio Astrometry) [PDF]
Proceedings of the International Astronomical Union, 2004 VLBI – Very Long Baseline Interferometry – is a radio interferometry technique which provides the highest spatial resolution observations to human kind. But at the present, the accuracy of the astrometry observations is limited by the atmospheric light path variations and instrumental phase errors, and only group delay measurements are used.
Hideyuki Kobayashi +9 more
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