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LOFAR opens up the low-frequency universe - and starts a new SETI search

Last Updated on Tuesday, 13 April 2010 19:24
Published on Tuesday, 13 April 2010 19:24

The Low Frequency Array (LOFAR), a new pan-European radio astronomy facility, has started mapping the Universe at very low energy wavelengths, a part of the electromagnetic spectrum that is relatively unexplored. It will detect faint signals from the first stars and mini-black holes that emerged when the Universe was only 500 000 years old – and will also be looking for signs of other civilisations in the Universe closer to home. Dr John McKean will present the first images at the RAS National Astronomy Meeting (NAM) 2010 in Glasgow on Tuesday 13th April.

"We are still in the construction phase of the project, with 21 out of the 44 planned stations in place. But even now, we are producing images of galaxies that are truly outstanding. Our first images show the emission from radio galaxies with jets of material that are ejected at relativistic speeds from the central supermassive black hole, ending with hot-spots as the material clumps together. The image quality from LOFAR is just amazing, compared to telescopes we have been using up until now," said Dr McKean, of the Netherlands Institute for Radio Astronomy (ASTRON).

Astronomers plan to use LOFAR to study the many cosmic rays that impact the Earth every day, pulsars and the magnetic field within our own and nearby galaxies. LOFAR will also compile a census of billions of radio emitting galaxies from the very early Universe, helping us to understand how galaxies formed and evolved over cosmic time.

In addition, the Search for Extraterrestrial Intelligence (SETI) will use LOFAR to search for low frequency radio signals from civilisations on planets orbiting nearby stars.  The first phase of this SETI programme will study how contamination from terrestrial transmitters can be weeded out and show the sensitivity of LOFAR for SETI work. An extended programme of looking at the nearby stars is then planned. The first high-spectral resolution spectrum in the test programme has just been obtained and will be shown.

Dr Alan Penny, who is presenting the LOFAR SETI programme at NAM 2010, said, "LOFAR will scan nearby stars searching for radio emissions which could only be produced by artificial means - a sign that there is a civilisation there and that we are not alone. Previous investigations of these stars have concentrated on higher frequencies but, as we do not know at which frequencies an extraterrestrial civilisation might choose to emit radio waves, LOFAR will fill an important gap in the search. It is particularly exciting that this is being done by a European team with a pan-European telescope."

"It's exactly 50 years since the first SETI observations were conducted by Frank Drake. LOFAR will expand on conventional SETI search strategies by observing in a very different frequency domain and with a huge field of view. The prospects are intriguing to say the least!” said Professor Mike Garrett, the Director General of ASTRON.

The telescope is being built by ASTRON, and when completed, will consist of at least 44 independent stations spread across the Netherlands, Germany, Sweden, France and the United Kingdom. Working at low frequencies means the telescope has to be very large to see fine detail, and this is achieved by having the stations spread over hundreds of miles.  Each station is made up from many small elements of antennae and tiles that measure the radio emission from the sky. These signals are then combined and processed using a supercomputer to make very detailed and deep images. The final stations of LOFAR are expected to be in place by summer 2010, after which the science phase of the project will begin, starting with surveys of the radio sky aimed at finding the most distant galaxies known.

"The amazing sensitivity and resolution of LOFAR is giving us an unprecedented view of how our Universe has evolved over billions of years. The low-frequency part of the electromagnetic spectrum has never been looked at to the level of detail that LOFAR will allow; we are expecting to find new types of galaxies that have just never been seen before," said Dr McKean.


Dr John McKean
Netherlands Institute for Radio Astronomy
P.O. Box 2
7900 AA Dwingeloo
The Netherlands
E-mail: mckean<at>

Dr Alan Penny
School of Physics and Astronomy
University of St Andrews
North Haugh
St Andrews KY16 9SS
United Kingdom
Office Tel: +44 (0) 1334 461672
Email: alan.penny<at>
Home page:

Prof. Mike Garrett
General Director ASTRON
Netherlands Institute for Radio Astronomy
P.O. Box 2
7900 AA Dwingeloo
The Netherlands
Mobile: +31621201417
Email: garrett<at>

Femke Boekhorst
Netherlands Institute for Radio Astronomy
P.O. Box 2
7900 AA Dwingeloo
The Netherlands
Tel: +31 521 595 204
E-mail: boekhorst<at>


Fig 1 - The massive radio galaxy 3C61.1 at 173 MHz measured with LOFAR. At the centre of the object is a supermassive black hole that powers two relativistic jets of material (north-south). At the end of the jets are two hotspots; areas where the material is concentrated as the jets impact with the environment around the radio galaxy. The radio emission extends over 2.5 million light years. Image credit:  van Weeren / ASTRON.

Fig 2 - A comparison of the LOFAR image with the results from other radio telescopes at various observing frequencies. The Very Large Array image at 74 MHz and Westerbork Synthesis Radio telescope image at 325 MHz, shown to the same scales, provided the previous state-of-the-art images at low frequencies. The image quality with LOFAR at 173 MHz is well beyond what has been done before in terms of sensitivity and resolution. Image credit: van Weeren / ASTRON.

Fig 3. A NASA simulation of a narrow-band radio emission from a civilisation 60 light years away from us. This show how the radar signal from a telescope like that at Arecibo in Puerto Rico would look
like if detected by the Arecibo telescope here on Earth. The broad signal from the left is that from interstellar hydrogen, showing how the narrow frequency of the radar signal is easily distinguished from the wide natural hydrogen emission. Image credit: NASA

Fig 4.  A LOFAR station. This show the 'tiles' of the Low Band Array and the High Band Array at the Eiffelsberg LOFAR station outside Bonn in Germany. The white structures at the upper left are the Bonn 100-metre radio telescope from which this photograph was taken. Image credit: ASTRON/ MPIfR



The LOw Frequency Array (LOFAR) is a pan-European radio telescope currently under construction, working at 10 to 240 MHz (compared to the ~ 0.4 - 3 GHz of 'normal' radio telescopes). Its main application is astronomy at low frequencies but it also has geophysical and agricultural applications.

The radio interferometric array of LOFAR consists of many low-cost antennas. These ‘sensors’ are organised in aperture array stations. 36 stations are being constructed in the Netherlands, distributed over an area about one hundred kilometres in diameter located in the North-East of the country.

Several international stations are also being built in Germany (5), Sweden (1), the UK (1) and France (1). The international stations are owned by their host institutes. The largest baselines across Europe are of the order of 1500 kilometres.

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The RAS National Astronomy Meeting 2010 will take place from 12-16th April at the University of Glasgow. The conference is held in conjunction with the UK Solar Physics (UKSP) and Magnetosphere Ionosphere and Solar-Terrestrial Physics (MIST) meetings. NAM2010 ( is principally sponsored by the Royal Astronomical Society (RAS) and the University of Glasgow.


The Royal Astronomical Society (RAS:, founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.


The University of Glasgow (founded 1451) is one of the world’s top 100 research universities with more than 70 per cent of its research rated as world-leading or internationally excellent. The Physics and Astronomy Department is one of the top four in the UK’s major research-intensive universities, the Russell Group.

The conference comes to Glasgow during the 250th anniversary year of the founding of the Regius Chair of Astronomy at the University of Glasgow, first held by astronomer and meteorologist Alexander Wilson in 1760. The present incumbent is Prof. John Brown, 10th Astronomer Royal for Scotland.