Very Long Baseline Interferometry (VLBI) relies on simultaneous observing of a celestial target with an array of radiotelescopes spread over the Earth’s surface and distant by thousands of kilometers. The target may be a natural radio source (quasar, star from the Galaxy,…) or an artificial one (planetary spacecraft). Owing to the angular resolution reached by such an array (a few nanoradians), the targeted source may be imaged with unsurpassed details. Furthermore, VLBI has the ability to establish ultra-precise (terrestrial and celestial) reference frames. This is essential e.g. for navigating interplanetary spacecrafts, monitoring irregularities in the Earth’s rotation, or measuring tectonic plate motions in real time.
By its very nature, VLBI requires international cooperation. Three major observing networks are available today: the European VLBI Network (EVN), The US Very Long Baseline Array (VLBA) and the array run by the International VLBI Service for geodesy and astrometry (IVS). Observations conducted on the EVN and the VLBA are selected following calls for proposals, while those run by IVS result from agreement between member observatories of the service. Topics of research embrace many fields, including astrophysics, astrometry and reference systems, fundamental physics, geodesy, geophysics,…
The LAB conducts astrometric and astrophysical research taking advantage of these three VLBI networks. A specific area of interest concerns the celestial frame and the reference quasars (VLBI imaging and determination of the astrometric position of those quasars). The LAB develops the Bordeaux VLBI Image Database (BVID) and is an IVS analysis center.
Scientific contact: Patrick Charlot