Welcome to this new edition of the LOFAR2.0 Newsletter, which aims to inform everybody involved in the development of LOFAR2.0 about what is going on in the Program. The items are short, and you are encouraged to approach the authors if you would like to learn more about a particular subject. I would like to invite you to contribute to the next edition. Please contact your project manager or me when you have an item.

From my point of view, the last 2 months were busy and successful. A major milestone was of course the successful System Review in April. After a very constructive review meeting, the Review Panel did not identify showstoppers in our approach and baseline documentation. This is a major achievement because this is the first time at ASTRON that such a solid systems engineering approach is applied at this scale. It also means that we progress our activities as planned and shifted focus to the upcoming PDR of the Station and Timing Distributor sub-system. Fortunately, the long-awaited software developers were added to the team. As you can see on the photo below, Jan David, Marcel and Thomas started working on the software design for the Central Processor, the Telescope Manager and the Station sub-systems with a big smile!

Wim van Cappellen.

System Review

Wim van Cappellen

After a period of intense preparations, the LOFAR2.0 Stage 1 System Review has been successfully concluded in April. The System Review was an independent review of the LOFAR2.0 science and system requirements, and the system architecture. The LOFAR2.0 team has worked very hard to deliver the documents for review. The Review Panel, consisting of Carla Baldovin, (chair, ASTRON), Daniel Hayden, (SKAO), Maaike Mevius (ASTRON), Adriaan Peens-Hough (SARAO), Arno Schoenmakers (ASTRON) and Reinout van Weeren (Leiden University) submitted a total of 343 observations. In its feedback, the panel acknowledged the complexity of the LOFAR2.0 program and the very stringent constraints imposed, in particular in terms of schedule and budget.

The review meeting was very constructive, in particular because the external panel members shared their experience from similar projects. The panel concluded that the team is committed to have in place a robust systems engineering approach, and that the selected approach is sensible given the nature of the program. As expected, the panel confirmed that activities at the system level need to continue to finalise the science and system level requirements.

LOFAR2.0 Day at annual LOFAR Science Meeting

Jason Hessels

The LOFAR scientific community meets annually to discuss the latest results from the ongoing observations with the telescope, as well as future plans. The most recent “LOFAR Family” meeting took place from May 20th to 23rd in Leiden.

The scientific talks are complemented by an annual LOFAR Users Meeting in which the status of the telescope and community feedback are collected. This year there was also a specific day reserved to discuss ongoing upgrades and future dreams for the telescope.

Carole Jackson kicked off this LOFAR2.0 Day by giving ASTRON’s view of LOFAR and its possible futures. Jason Hessels followed on with a detailed discussion of DUPLLO and the process for identifying other major upgrades. Wim van Cappellen explained the LOFAR2.0 Programme and the Stage 1 developments, and Cees Bassa presented the status and commissioning of COBALT2.0. After the coffee break, Francesco de Gasperin (U. of Hamburg) presented the status of current LBA imaging, and how the DUPLLO upgrade will transform this. The LOFAR2.0 Day was then rounded out by two pitches for possible future LOFAR upgrades, post Stage 1: Huub Röttgering (U. of Leiden) made the case for expanded uv coverage and Ralph Wijers (U. of Amsterdam) gave the motivation for sensitive all-sky monitoring.

Particularly impressive were the latest results from long-baseline imaging, which demonstrated how LOFAR’s future lies in exploiting its unparalleled angular resolution (0.2 arcseconds in the high-band). The LOFAR2.0 Day was a great way to round out an inspiring week of LOFAR science results with a look towards the science to come in the next decade.

Testing the new brain of LOFAR

Cees Bassa

The COBALT 2.0 hardware, consisting of 13 production nodes, each with two state of the art CPUs (Intel Xeon 6140) and two state of the art GPUs (NVIDIA Tesla V100), is at least a factor 5 more powerful than COBALT, the current correlator and beamformer. The hardware is currently being put up to the test in a series of commissioning tests to validate the COBALT software on the new hardware.

The commissioning observations test the COBALT 2.0 stability and performance, as well as the equivalence of its output with that of COBALT. Our equivalence tests show that the differences between COBALT and COBALT 2.0 are consistent with numerical round off, while the performance is significantly improved.

This paves the way to upgrading the COBALT software and implementing the LOFAR Mega Mode, in which COBALT 2.0 performs multiple correlation and beamforming operations simultaneously to serve different science cases.

Image: COBALT 2.0 first light observations of a bright point source (3C48) and a bright pulsar (B0329+54).

LOFAR 2-20’s (LOFAR to twenties)

Johan Pragt

LOFAR 2-20’s (to twenties) is a project under the umbrella of LOFAR 2.0. It is a shared project between 4 partners: Neways, Major, Ampulz and ASTRON. Within ASTRON we are developing frontend hardware, including systems engineering and management.

The partners are focussing on developments direct or indirect for LOFAR like: fast prototyping for pcba’s (Neways), lower energy production tooling and improved production processes for recovering materials (Major) and low RFI power converters for PV-farms and related markets (Ampulz).

The goal of the project is improved valorisation of the LOFAR knowledge for (North) Netherlands SME’s within the astronomy market and other markets.

Latest tweets

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.
https://www.astron.nl/dailyimage/main.php?date=20220621

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.
https://www.astron.nl/dailyimage/
#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.
https://www.astron.nl/dailyimage/main.php?date=20220607

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