The world's largest collection of radio telescopes is being tied together for 24 hours starting today to observe more than two hundred energetic galaxies known as quasars.
During those 24 hours, 35 telescopes on all seven continents will observe 243 distant quasars in an effort to improve the precision of the reference frame scientists use to measure positions in the sky.
The quasars, galaxies with supermassive black holes at their cores, are profuse emitters of radio waves, and also are so distant that, despite their actual motions in space, they appear stationary as seen from Earth.
This lack of apparent motion makes them ideal celestial landmarks for anchoring a grid system, similar to earthly latitude and longitude, used to mark the positions of celestial objects.
In a technique called very long baseline interferometry (VLBI), data from all the radio telescopes will be combined to make them work together as a system capable of measuring celestial positions with extremely high precision.
The previous record for such an effort was a 23-telescope observation.
The International VLBI Service for Geodesy and Astrometry is coordinating the record-breaking effort.
At a meeting in Brazil last August, the International Astronomical Union adopted a new reference frame that uses a set of 295 quasars to define celestial positions that will be used starting on January 1.
Improving the celestial positional grid will allow astronomers to better pinpoint the locations and measure the motions of objects in the sky. As astronomers increasingly study objects using multiple telescopes observing at different wavelengths, such as visible light, radio and infrared, the improved positional grid will allow more accurate overlaying of the different images.
This set of quasars also serves as a guiding post for Earth's GPS systems.
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