THE CELESTIAL REFERENCE FRAME AT 24 AND 43 GHz. II. IMAGING
| Autor: | Patrick Charlot, L. D. Zhang, David A. Boboltz, B. J. Geldzahler, G. E. Lanyi, Alan L. Fey, Edward B. Fomalont, O. J. Sovers, Christopher S. Jacobs, C. J. Naudet, Chopo Ma, David Gordon, Jonathan D. Romney |
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| Přispěvatelé: | Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1, US Naval Observatory (US NAVAL OBSERVATORY), US Naval Observatory, National Radio Astronomy Observatory (NRAO), NASA Goddard Space Flight Center (GSFC), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH) |
| Rok vydání: | 2010 |
| Předmět: |
[PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
010504 meteorology & atmospheric sciences FOS: Physical sciences Flux Astrophysics 01 natural sciences [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO] 0103 physical sciences 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics Very Long Baseline Array 0105 earth and related environmental sciences Physics Spacecraft business.industry Astrophysics::Instrumentation and Methods for Astrophysics Astronomy and Astrophysics Quasar Astrometry Astrophysics - Astrophysics of Galaxies Galaxy [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Fiducial marker business Reference frame |
| Zdroj: | The Astrophysical Journal The Astrophysical Journal, American Astronomical Society, 2010, 139 (5), pp.1713-1770. ⟨10.1088/0004-6256/139/5/1713⟩ |
| ISSN: | 1538-3881 0004-6256 0004-637X 1538-4357 |
| DOI: | 10.1088/0004-6256/139/5/1713 |
| Popis: | We have measured the sub-milli-arcsecond structure of 274 extragalactic sources at 24 and 43 GHz in order to assess their astrometric suitability for use in a high frequency celestial reference frame (CRF). Ten sessions of observations with the Very Long Baseline Array have been conducted over the course of $\sim$5 years, with a total of 1339 images produced for the 274 sources. There are several quantities that can be used to characterize the impact of intrinsic source structure on astrometric observations including the source flux density, the flux density variability, the source structure index, the source compactness, and the compactness variability. A detailed analysis of these imaging quantities shows that (1) our selection of compact sources from 8.4 GHz catalogs yielded sources with flux densities, averaged over the sessions in which each source was observed, of about 1 Jy at both 24 and 43 GHz, (2) on average the source flux densities at 24 GHz varied by 20%-25% relative to their mean values, with variations in the session-to-session flux density scale being less than 10%, (3) sources were found to be more compact with less intrinsic structure at higher frequencies, and (4) variations of the core radio emission relative to the total flux density of the source are less than 8% on average at 24 GHz. We conclude that the reduction in the effects due to source structure gained by observing at higher frequencies will result in an improved CRF and a pool of high-quality fiducial reference points for use in spacecraft navigation over the next decade. Comment: 63 pages, 18 figures, 6 tables, accepted by the Astronomical Journal |
| Databáze: | OpenAIRE |
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