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.
advertisement
