Astronomers at ASTRON have, by simultaneously detecting the radio signals of two widely separated pulsars, demonstrated the feasibility of a new receiver technology that will have a great impact on radio astronomy. This achievement is part of the development of a new wide-field radio camera, Apertif, for the Westerbork Synthesis Radio Telescope (WSRT). The new result signals the coming of a new era in radio astronomy. The demonstration of simultaneous Apertif pulsar observations is very exciting for researcher Dr. Joeri van Leeuwen: "The possibility of simultaneous observations of more than one pulsar opens up completely new ways for pulsar research. Pulsars are among the most extreme and interesting objects in the sky, and the new radio camera will lead to the discovery of many hundreds of new pulsars."

Published by the editorial team, 22 November 2010

Dr. Tom Oosterloo, co-Principal Investigator of Apertif, adds: " With the new wide-field camera, the WSRT will be more than thirty times faster in surveying the sky: observations which would take a month with the old WSRT can now be completed in a single day! This increase in observing speed will no doubt lead to many exciting discoveries, not only of pulsars, but also of galaxies, transient sources and potentially new, as yet undiscovered, cosmic phenomena.

Not only Dr. van Leeuwen is excited about the new possibilities offered by Apertif. Many astronomers have recognised the high scientific potential of Apertif and are very interested in getting their share of the action. Astronomers from all of the world will descend on Dwingeloo on November 22 an 23 in order to discuss the full range of scientific opportunities Apertif will enable. According to Dr. Rene Vermeulen, director of the Radio Observatory at ASTRON: "There has been an overwhelming response to our call for expressions of interest in Apertif, and it is clear that the WSRT-Apertif combination will have an extremely busy calendar."

For more information, please contact:

Dr. Tom Oosterloo, senior astronomer. Tel.: 0521 595 100. E-mail:

Femke Boekhorst, PR & Communication. Tel.: 0521 595 204. E-mail:


More information about Apertif:

The Apertif project concerns the replacement of the current radio receivers mounted at the focal point of each of the 14 WSRT dishes. The new Apertif receiver consists of an array of more than 100 simple antenna receptors that will act very much like a radio camera. This revolutionary new camera concept widens the existing field-of-view of the Westerbork telescope by more than a factor thirty - an area on the sky equivalent to about 30 times the angular size of the moon! Such an expansion in the WSRT's field-of-view permits astronomers to study galaxies, pulsars and magnetic fields in the universe, in a new and unprecedented manner. The required technological development for this advanced antenna system has been funded via grants from Netherlands Organisation for Scientific Research (NWO) and the European Commission (EC).

ASTRON has a strong tradition in developing and implementing new technologies for radio astronomy, and is recognised internationally to play a leading role in this area. The technological research and development is focused on the implementation of so-called ‘Antenna Array' technology, superseding the classic idea of dishes, each with a single receiver. By employing ‘Antenna Array' technology for radio telescopes, it becomes possible to observe larger areas of the sky much faster.

The new possibilities offered by Apertif have recently been demonstrated with a prototype system installed in one of the WSRT dishes. The current WSRT can detect only sources that are not further apart than about the diameter of the full moon. With the Apertif prototype it has been possible to observe two pulsars* simultaneously that are separated more than 7 times this distance.

The picture illustrates the new capabilities of Apertif. The circles show the location on the sky of the two pulsars detected simultaneously, separated from each other by about seven times the diameter of the full moon. The moon indicates the field of view of the old WSRT: it can detect sources only if they are closer to each other a distance similar than the size of the full moon. The inset on the left shows the average time profile of the pulsars detected.

*pulsars are cosmic lighthouses. They are collapsed stars about as massive as the Sun but squeezed into a size of only 15 km across and which have an incredibly strong magnetic field. They are spinning around very fast, may of them even more than 10 times in a second. They emit beams of radiation which are detected as a pulsed radio signal (beep beep beep...).


Latest tweets

Today, construction on the #SKA radio telescope officially started. Together with @CGI_Global, S[&]T, and @TriOpSys we are already developing important software components for processing the vast amounts of data the SKA telescope will produce.

Today was the official start of the construction of the @SKAO's #SKA radio telescope in Australia and South Africa. Together with #TOPIC, we are already working on the development of the central signal processor for the SKA Low frequency telescope.

Gigantic radio sources up to ten million light years in size discovered in the universe using the LOFAR radio telescope. Read more about this exciting result on the website of @HambObs

Daily image of the week

On June 13-17, the LOFAR Family Meeting took place in Cologne. After two years LOFAR researchers could finally meet in person again. The meeting brings together LOFAR users and researchers to share new scientific results.