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Celestial Reference Frames based on AGN: Issues in tying radio to optical frames

Chris Jacobs
JPL, Caltech


The most stable celestial reference frames are now built using observations of extragalactic sources such as quasars. These frames are used for astrometry, navigation, and geodesy.

The current IAU standard frame which defines coordinates on the sky is the ICRF-2 built using radio interferometry (VLBI). It is accurate to about 100 µas (~5.e-10 radians). This talk will discuss the the construction of radio-based frames using VLBI including the next generation ICRF-3.

With the launch of ESA’s Gaia mission which observes at optical wavelengths, we expect for the first time to have two totally independent techniques for building sub-nanoradian frames. We will discuss effects which may create offsets between the optical and radio centroids of objects common to both Gaia and VLBI.

2015 May 14, 14:00

Observatůrio Astronůmico de Lisboa (Seminar room)
Tapada da Ajuda, 1349-018 Lisboa

Instituto de Astrof√≠sica e Ci√™ncias do Espa√ßo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia