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Astrowatch

29 January 1999

Edited by Emma Sanders

The furthest quasar

Astronomers at the Sloan Digital Survey have broken the record for the most distant quasar ever observed.

Quasars ­ quasi-stellar objects ­ are no larger than our solar system,
yet can outshine galaxies of hundreds of billions of stars. The new record-breaker has a redshift of 5.0. Because of the expansion of the universe,
the greater a galaxy’s light is shifted to the red,
the further away it is,
and the younger the universe when the light was emitted. A redshift of 5.0 means the light was emitted when the universe was less than a billion years old.

The most distant galaxy has been observed with the Hubble Space Telescope at a redshift of 5.60.

The Sloan survey uses the 2.5 m telescope at the Apache Point Observatory in New Mexico. Over the next five years,
astronomers will measure the distance of over a million galaxies which will combine to make the largest 3-D map of the universe ever. This will impose important constraints on models of cosmic evolution.

The collaboration consists of eight research organizations from the US and Japan. Fermilab constructed the data acquisition system and the software and hardware to process the 10­20 terabytes of data.

New infrared array

Europe and the United States plan to join forces on the next generation of ground-based infrared telescopes. The European project,
the Large Southern Array,
consists of antennae covering an area of 10 000 m2 in the Chilean Andes. In parallel,
staff at the US National Radio Astronomy Observatory have designed their own Millimetre Array.

The proposal now up for discussion is whether or not to pool resources and build just one telescope. The council of the European Southern Observatories (ESO) has given the green light for negotiations to start.

A new millimetre-wavelength telescope is a high priority for astronomers as it will complement observations made by the
Hubble Space Telescope and
ESO’s Very Large Telescope.
All three would have similar scientific objectives and
comparable high angular resolution and
sensitivity.

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