10 years of LOFAR highlights: Using the existing SurfNet infrastructure to connect international stations and its European counterparts

By Peter Maat

In addition to the 40 Dutch antenna stations, LOFAR has 14 antenna stations elsewhere in Europe. Just like the antenna stations in the Netherlands, the European stations also send their observation data via fibre optic connections to the central processor (CEP) of LOFAR at Groningen.

Published by the editorial team, 8 June 2020

In the Netherlands, LOFAR uses its own, dedicated fiber optic network to send observation data from the stations to CEP. Although such an approach would be possible for the European part from a technical point of view, a European wide dedicated fiber optic LOFAR network can not be realised due to the extremely high construction and maintenance costs. For the European stations, a more cost-effective approach to data transport was chosen by using the facilities of the National Research and Education Networks (NRENs) in Europe.

At the time of the construction of LOFAR, so-called Lightpath technology became available at the European NRENs with which 10 Gb/s point-to-point connections can be realized. As one of the first users of Lightpath technology, all LOFAR stations in Europe are equipped with the required broadband, direct connections to Groningen. The construction of the lightpaths has been realized together with the Dutch NREN Surfnet, in collaboration with the other NRENs along the various connections. It was important to configure the interfaces of the NREN router systems in such a way that interconnections are possible.

Even 10 years after the opening of LOFAR, the LOFAR Lightpaths still provide the direct connections between the European LOFAR stations and Groningen that are required for the streaming data in the LOFAR telescope.

LOFAR station in Latvia, credit: ASTRON


Lofar stations across Europe, credit: ASTRON


On 12 June 2020, LOFAR celebrates its tenth anniversary. The radio telescope is the world’s largest low frequency instrument and is one of the pathfinders of the Square Kilometre Array (SKA), which is currently being developed. Throughout its ten years of operation, LOFAR has made some amazing discoveries. It has been a key part of groundbreaking research, both in astronomy and engineering. Here we feature some – but definitely not all – of these past highlights, with surely more to come in the future.



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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.

Our renewed ‘Melkwegpad’ (Milky Way Path) is finished! The new signs have texts in Dutch on the one side and in English on the other side. The signs concerning planets have a small, 3D printed model of that planet in their centre.
#Melkwegpad @RTVDrenthe

Daily image of the week

The background drawing shows how the subband correlator calculates the array correlation matrix. In the upper left the 4 UniBoard2s we used. The two ACM plots in the picture show that the phase differences of the visibilities vary from 0 to 360 degrees.

Daily image of the week: Testing with the Dwingeloo Test Station (DTS)
One of the key specifications of LOFAR2.0 is measuring using the low- and the highband antenna at the same time. For this measurement we used 9 lowband antenna and 3 HBA tiles.