Selecting defining sources for the next ICRF based on source structure

P. Charlot (1, 2, 3) , A. L. Fey (4) , A. Collioud (1, 2, 3) , R. Ojha (4) , D. A. Boboltz (4) , J. I. B. Camargo

1 L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux
2 OASU - Observatoire aquitain des sciences de l'univers
3 LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac]
4 US NAVAL OBSERVATORY - US Naval Observatory

The intrinsic radio structure of the extragalactic sources is one of the limiting errors in the definition of the International Celestial Reference Frame (ICRF). This paper reports about the ongoing work to monitor the structural evolution of the ICRF sources by using the Very Long Baseline Array and other VLBI telescopes around the world. Based on more than 5000 VLBI images produced from such observations, we have assessed the astrometric suitability of 80% of the ICRF sources. The number of VLBI images for a given source varies from 1 for the least-observed sources to more than 20 for the intensively-observed sources. From this analysis, we identify a subset of 194 sources that are highly compact at any of the available epochs. Such sources are prime candidates to define the next ICRF with the highest accuracy.

Domaines: Planétologie et astrophysique de la terre [astro-ph.EP]; Planétologie et astrophysique de la terre [astro-ph.EP]

P. Charlot, A. L. Fey, A. Collioud, R. Ojha, D. A. Boboltz, et al.. Selecting defining sources for the next ICRF based on source structure. Journées Systèmes de Référence Spatio-temporels 2007, Sep 2007, Paris, France. pp.8. ⟨hal-00401825⟩