منابع مشابه
The Reconciliation of Optical and Radio Positions
Reconciliation of optical and radio postions is basically a matter of reconciling positional reference systems. For example, the question of whether, for a given source, there is a real physical off-set between the optical and radio centroid at a given frequency cannot be properly inves tigated until the reference systems have been securely established. In the more sophisticated case of the co...
متن کاملCelestial positions in radio and optical
We discuss the importance of the direct link between the most accurate radio and optical reference frames that will become possible with the next-generation space as-trometry missions in about a decade. The positions of more than 500 active galactic nuclei that are common in the precise Very Long Baseline Interferometry (VLBI) catalogues and the Sloan Digital Sky Survey (SDSS) Data Release 4 (D...
متن کاملDetermination of optical positions for 23 extragalactic radio sources
AB S TRACT The optical counterparts of 23 extragalactic radio sources, of which 13 are in the southern hemisphere, have been observed by three telescopes equipped with CCDs. By reference to the Astrographic/Tycho (ACT) Reference, Carlsberg Meridian (CMC), Positions and Proper Motions (PPM), Hipparcos (HIP) and Lick Northern Proper Motion (NPM) catalogues, the positions of the 23 objects have be...
متن کاملOptical tracking of finger positions
2.3. Solution Assembly simulations and ergonomical studies are major fields for Virtual and Augmented Reality in industry. Both applications require direct object manipulation as the essential interaction method. Finger tracking is a tool, which allows to recognize finger positions without disturbing gloves and cables. Active markers allow to solve both the size and robustness problem: passive ...
متن کاملRadio astrometry with chromatic AGN core positions
Aims. The effect of frequency-dependent AGN core positions (“core-shifts”) on radio Very Long Baseline Interferometry (VLBI) global astrometry measurements is investigated. Methods. The basic equations relating to VLBI astrometry are reviewed, including the effects of source structure. A power-law representation of core-shifts, based on both observations and theoretical considerations of jet co...
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ژورنال
عنوان ژورنال: Astronomy and Astrophysics Supplement Series
سال: 1996
ISSN: 0365-0138,1286-4846
DOI: 10.1051/aas:1996201