* Astronomy

Thirty-five radio telescopes around the world will conduct an unprecedented continuous 24-hour observation of nearly 250 remote quasars this week. The collection of quasars, whose positions in the sky are precisely known, forms the core (or defining sources) of a grid of celestial landmarks called the International Celestial Reference Frame (ICRF2), which was officially recognised as the fundamental reference system for astronomy by the International Astronomical Union (IAU) in August 2009. The ICRF2 has 295 defining sources that are spread evenly over the sky and out of which 243 will be observed. The small number of stations in the Southern Hemisphere is the reason why some of the southern defining sources will not be observed. The observation, the largest of this type ever conducted in terms of both the number of participating telescopes and the number of quasars to be observed, will mark the kickoff for the use of this new system. The session is also organised as a specific event for the International Year of Astronomy (IYA2009) and is dedicated to reach out to the public and to promote science with open doors at the radio telescopes.
Telescopes in Asia, Australia, Europe, North America, South America, Antarctica, and in the Pacific will coordinate for the observation, forming a special network called a Very Long Baseline Interferometer (VLBI). Such a network has the spatial resolution of a radio telescope as large as the network, allowing one to pinpoint positions of quasars to unprecedented precision. The 35-element world-size radio telescope that was put together for the event will be unique in its ability to observe most of the ICRF2 quasars at once and to strengthen the ICRF2 grid.
The observation is coordinated by the International VLBI Service for Geodesy and Astrometry (IVS) and will take place from Wednesday 18 November, 18:00 UT to Thursday 19 November, 18:00 UT.

Source IYA2009

Read more

See more