10 years of LOFAR highlights: The construction and use of our own broadband optical data transport system

By Peter Maat

In the Netherlands, the LOFAR telescope consists of approximately 40 antenna stations that are spread over the entire North of the Netherlands. The amount of LOFAR data that needs to be transferred from these stations is so large that it cannot be sent via the regular Internet. Specially constructed fibre optic connections are required to transport a large amount of astronomy data from the stations to Groningen.

Published by the editorial team, 2 June 2020

The antenna stations of LOFAR receive astronomical data which, after an initial processing step, are forwarded to a central computer system, which is placed at the Center for Information Technology (CIT) of the RU Groningen. During the construction of LOFAR, a new fibre optic cable was installed towards each station. Where possible, this cable is placed (blown) in an existing tube with other cables. But in many places, especially close to the antenna stations, digging also had to be done to get the fibre optic cables in the ground. Once all fibre optic cables were in place, special optical communication equipment was purchased via a tender. In this way, each LOFAR station was equipped with a 10 Gb/s optical connection to the CIT.


To date, this bandwidth has been sufficient to adequately provide data to all astronomers. Nowadays, consideration is being given to further increasing the bandwidth from each station. This possible upgrade can be realized by adjusting the communication equipment at the stations and at the CIT. The glass fibres do not need to be adjusted: thanks to their gigantic potential bandwidth, we can continue with them for years to come.

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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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.