NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-27 T05:25:06 PDT
Help | Comment | NED Home

For refcode 2000ApJS..128...17F:
Retrieve 225 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
2000ApJS..128...17F VLBA Observations of Radio Reference Frame Sources. III. Astrometric Suitability of an Additional 225 Sources Alan L. Fey U.S. Naval Observatory, 3450 Massachusetts Avenue NW, Washington, DC 20392-5420; afey@usno.navy.mil and Patrick Charlot Observatoire de Bordeaux-CNRS/UMR 5804 2 Avenue de l'Observatoire, BP 89, 33270 Floirac, France; charlot@observ.u-bordeaux.fr Received 1999 August 25; accepted 1999 December 9 ABSTRACT We present simultaneous dual-frequency Very Long Baseline Array 2 and 8 GHz observations of 225 of the 560 extragalactic sources for which positions were reported by Johnston and coworkers and which are now part of the International Celestial Reference Frame. These observations represent the third and final in a series of observations intended to obtain single- epoch images of the entire set of sources presented by Johnston and coworkers and, together with previously reported observations, bring the total number of sources observed to 389. As with previous papers in this series, we use these data to quantify the magnitude of the expected effect of intrinsic source structure on astrometric bandwidth synthesis Very Long Baseline Interferometry observations and to calculate a source "structure index" for the observed sources. The structure index can be used as an estimate of the astrometric quality of the sources. Based on this indicator, correlations between the observed radio structure and the astrometric position accuracy and stability of the sources have been found. These correlations indicate that the more extended sources have larger position uncertainties and are less positionally stable than the more compact sources. Subject headings: astrometry-quasars: general-radio continuum: galaxies- surveys
Retrieve 225 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home