New Sub-Millimetre Light in the Desert (Forwarded)

ESO Education and Public Relations Dept.

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Text with all links and the photos are available on the ESO
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http://www.eso.org/outreach/press-re.../pr-18-05.html
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Contacts

Karl Menten
Max-Planck-Institute for Radioastronomy, Bonn, Germany
Phone: +49 228-52 52 97

Robert Laing
ESO, Garching
Phone: +49 89 3200 6625

Lars Aake Nyman
APEX, Sequitor Base, Chile
Phone: +56 2 582 02 00

For immediate release: 14 July 2005

ESO Press Release 18/05

New Sub-Millimetre Light in the Desert

APEX telescope Sees First Light at Chajnantor

ESO PR Photo 21/05
The APEX Telescope at Chajnantor

The Atacama Pathfinder Experiment (APEX) project has
just passed another major milestone by successfully
commissioning its new technology 12-m telescope, located
on the 5100m high Chajnantor plateau in the Atacama Desert
(Chile). The APEX telescope, designed to work at
sub-millimetre wavelengths, in the 0.2 to 1.5 mm range,
has just performed its first scientific observations. This
new front-line facility will provide access to the "Cold
Universe" with unprecedented sensitivity and image quality.

Karl Menten, Director of the group for Millimeter and
Sub-Millimeter Astronomy at the Max-Planck-Institute for
Radio Astronomy (MPIfR) and Principal Investigator of the
APEX project is excited: "Among the first observations,
we have obtained wonderful spectra, which took only
minutes to take but offer a fascinating view of the
highly complex organic chemistry in star-forming regions.
In addition, we have also obtained exquisite images from
the Magellanic Clouds and observed molecules in the
active nuclei of several external galaxies. Traditionally,
telescopes turn to weak extragalactic sources only after
they are well in operation. With APEX, we could pick
them amongst our first targets!"

Because sub-millimetre radiation from space is heavily
absorbed by water vapour in the Earth's atmosphere, APEX
is located at an altitude of 5100 metres in the high
Chilean Atacama desert on the Chajnantor plains, 50 km
east of San Pedro de Atacama in northern Chile. The
Atacama desert is one of the driest places on Earth, thus
providing unsurpassed observing opportunities -- at the
costs of the demanding logistics required to operate a
frontier science observatory at this remote place.

Along with the Japanese 10-m ASTE telescope, which is
operating at a neighbouring, lower altitude location, APEX
is the first and largest sub-millimetre facility under
southern skies. With its precise antenna and large
collecting area, it will provide, at this exceptional
location, unprecedented access to a whole new domain in
astronomical observations. Indeed, millimetre and sub-
millimetre astronomy opens exciting new possibilities in
the study of the first galaxies to have formed in the
Universe and of the formation processes of stars and
planets. APEX will, among other things, allow astronomers
to study the chemistry and physical conditions of molecular
clouds, that is, dense regions of gas and dust in which
new stars are forming.

APEX follows in the footsteps of the 15m Swedish-ESO
Submillimetre Telescope (SEST) which was operated at ESO
La Silla from 1987 until 2003 in a collaboration between
ESO and the Onsala Space Observatory. SEST operated in
the wavelength range from 0.8 to 3 mm. Says Catherine
Cesarsky, ESO's Director General: "SEST was for a long
time the only instrument of its kind in the southern
hemisphere. With it, ESO and our collaborators have
gained valuable operational experience with regard to
ground-based observations in the non-optical spectral
domain. With APEX, we offer the ESO community a most
exciting new facility that will pave the way for ALMA."

As its name implies, APEX is the pathfinder to the ALMA
project. It is indeed a modified ALMA prototype antenna
and is located at the future site of the ALMA observatory.
ALMA is planned to consist of a giant array of 12-m
antennas separated by baselines of up to 14 km and is
expected to start operation by the end of the decade. It
will bring to sub-millimetre astronomy the aperture
synthesis techniques of radio astronomy, enabling
precision imaging to be done on sub-arcsecond angular
scales, and will so nicely complement the ESO VLT/VLTI
observatory.

In order to operate at the shorter sub-millimetre
wavelengths, APEX presents a surface of exceedingly high
quality: after a series of high precision adjustments,
the APEX project team was able to adjust the surface of
the mirror with remarkable precision: over the 12m
diameter of the antenna, the deviation from the perfect
parabola is now less than 17 thousandths of a millimetre.
This is smaller than one fifth of the average thickness
of a human hair!

"From the engineering point of view, APEX is already a
big success and its performance surpasses our expectations",
says APEX Project Manager Rolf Güsten. "This could only
be achieved thanks to the highly committed teams from the
constructor, from the MPIfR and from the APEX project
whose endless hours of work, often at high altitudes,
made this project become reality."

In parallel to the construction and commissioning of the
APEX telescope, a demanding cutting-edge technology
program has been launched to provide the best possible
detectors for this outstanding facility. For its first
observations, APEX was equipped with state-of-the-art
sub-millimetre spectrometers developed by MPIfR's Division
for Sub-Millimetre Technology and, more recently, with
the first facility receiver built at Chalmers University
(OSO).

APEX is a collaboration between the Max-Planck-Institute
for Radio Astronomy (MPIfR), Onsala Space Observatory (OSO),
and the European Organisation for Astronomical Research in
the Southern Hemisphere (ESO). The telescope was designed
and constructed by VERTEX Antennentechnik GmbH (Germany),
under contract by MPIfR, and is based on a prototype
antenna constructed for the ALMA project. Operation of
APEX in Chajnantor is entrusted to ESO.

Background information on sub-millimetre astronomy and on the
first APEX results can be found as PDF files on the APEX Fact
Sheets page. A press release in German was also issued by the
Max-Planck Society.

National contacts for the media:

Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Terhi Loukiainen, +358 9 7748 8385
Denmark: Dr. Michael Linden-Vørnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Prof. Massimo Capaccioli, +39-081-55 75 511
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25

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