Newsletter format

The LOFAR newsletter has a new look; we have merged the LOFAR newsletter with the LOFAR Development newsletter. This new structure will combine important updates from both operational and development perspectives. The new LOFAR newsletters will be published every three months. To receive the newsletters, users should subscribe to the lofar-news mailing list.

LOFAR observations

LOFAR1.0 production observations ended at the end of observing Cycle 20 on 31 August, 2024. Efforts are now being invested into completing the LOFAR2.0 telescope upgrade to start LOFAR2.0 production operations.

Data staging and downloading from the LTA sites

Data staging and downloads from the LTA sites were stable in the past few weeks, except during the few planned maintenance days when the services were unavailable. Planned maintenance days are always announced on the LTA portal. Please, contact SDC-Helpdesk if you experience any unusual issues with staging and downloads.

LTA new user account

Users who need to create new LTA accounts should send a request via the SDC-Helpdesk. This should include the following information:

• • your title
  • your preferred username
  • email address (preferably institutional one)
  • name (first name + surname)
  • phone number
  • name and address of institution/affiliation
  • website/web address of affiliation
  • position

LOFAR2 Data Working Group Efforts

The LOFAR2.0 Data Working Group (L2DWG) has started its work on preparing data product specifications for all the products that the LTA will support for LOFAR2.0. The first deliverable is an inventory of the supported data products, which can be expected by mid-November. Where possible, data specifications will be adaptations of existing practices for LOFAR data. Supporting both used and generated data products in the LTA will be a pre-condition for the start of LOFAR2.0 science projects. In the meantime, the teams that have submitted Large Program proposals have been asked to prepare a Data Management Plan (DMP) and submit it by 14 December. Each program is expected to describe the processes for generating science level data and publications, starting from (supported) data products to be delivered by the instrument, the data processing that is envisioned to take place, the (supported) data products that will be delivered back to the LTA, and the publication plan. Submitted plans will be assessed for completeness, impact on LOFAR2.0 delivery, and readiness of the programs. Information contained in the DMP's will also be input for detailing and planning further development, commissioning and verification activities for the delivery of LOFAR2.0.

LOFAR Data Valorisation

The LOFAR Data Valorisation (LDV) project aims to give added value to LOFAR archived data in the Long-Term Archive (LTA) by offering users well curated and science-ready data. It also paves the way for LOFAR2.0 operations because it streamlines data processing operations at the LTA sites (currently SURF, Juelich and Poznan) and ensures sustainability of science operations by reducing data volume at the LTA, thereby also lowering the operational costs.
LDV is reaching the conclusion of its first phase of operations at SURF. The storage occupancy at this site was reduced by 7.5 PB through resampling of beamformed data, compression of interferometric data and a large data transfer from SURF to Juelich. This gain in storage translates into a saving of about 56 kEuro/yr. Curation of data enabled the removal of file duplicates and the addition of data quality flags. Additionally, within this project a major retirement action of early Cycle data with no legacy value has been started (~9.5 PB distributed over the three LTA sites). For more details see the following item of the newsletter on Early Cycle Data Retirement.
The next operational aim at SURF is the generation of higher-level data products by running the LOFAR Initial Calibration (LINC) pipeline on a significant portion of the archived data. This process will last for the whole of next year. Currently, the plan is to act on the HBA component of the data collection but depending on the availability of LBA workflows in the data processing system, a parallel LBA effort could also be run. For the first time, calibrated visibilities generated through the observatory processing framework will be offered to the astronomical community. Furthermore, efforts are ongoing to finalise the extension of the processing framework infrastructure towards the Juelich LTA site, to enable the next round of data editing operations with an expected duration of one year. As a result, more than 4 PB of additional tape storage space will be gained. At the time of writing, commissioning of the delivered system is complete, and an early operational phase has just started. Looking ahead, the LDV processing infrastructure will be expanded to support the LOFAR2.0 operations, marking a key step toward future-ready science operations.

Early cycles data retirement

In preparation for the start of LOFAR2.0 operations, we have started the process of removing early cycle data from the LOFAR Long-Term Archive. This includes data that has been observed and/or processed during cycle 0 up to and including cycle 6, i.e. from start of LOFAR operations until 1/12/2016. The data that will be retired has been selected by careful analysis and verification with the LOFAR community and the Program Committee (PC) for not having legacy value. Existing entries in the LTA catalogue will continue to be findable by querying the database but the associated data products will no longer be available for staging and download. As a result of the data retirement, attempts to stage data based on previously extracted file locations may fail if these include data being retired.

StageIT

The new LOFAR stager (called StageIT) will be rolled out on 24 November and the old stager will be retired on 1 December. Along with the current stager functionalities, StageIT will also offer a web-based user interface to submit, monitor, and handle data access requests. Users will be able to log in using their institutional account via the SRAM service when their institute is part of the eduGAIN federation. Users that don't have access to a federated institutional account can create a federated digital account with eduID. To allow for a smooth transition, the current users with StageIT accounts, and recent users of the API of the current stager, will be contacted shortly to give them an opportunity to modify their scripts and access method. which should be provided by 1 November for consideration to implement and document changes in StageIT before the official roll-out.

A list of the reported (known) issues is available online here: https://support.astron.nl/confluence/plugins/servlet/share/content/6c26d270-e5ab-4a4c-9561-9e77d5270f67

LOFAR Family Meeting 2025

There was yet another successful LOFAR Family Meeting (LFM2025) at the Institut de Physique du Globe de Paris, Paris, France between 22-26 September, 2025. The event gathered 140 LOFAR enthusiasts from all over the globe working on a broad spectrum of scientific topics. The program featured a diverse range of talks and posters showcasing recent findings and advancements in LOFAR science. An Observatory session on Tuesday afternoon showcased the status of the LOFAR2.0 upgrade and developments and the plans towards the start of the LOFAR2.0 operations. Emphasis was given to the commissioning activities of the instrument, for which a comprehensive overview of achievements was presented.
More information about the conference, including access to the presentations and resources shared during the event are available on the official conference website (https://indico.lofar.eu/event/24/overview).
The next edition of this meeting, the LOFAR Family Meeting 2026 (LFM2026) will take place during 8-12 June, 2026, at the Trinity College Dublin, Ireland. Stay tuned for future announcements on this!

LOFAR Data School 2026

We are happy to announce that the 8th LOFAR Data School (LDS2026) will take place at ASTRON, the Netherlands Institute for Radio Astronomy (Dwingeloo, The Netherlands) between 16-23 September, 2026. The first announcement can be found here. The school’s website is under development and will be functional in early 2026, which is when we expect registration to open. Note that registration to the school is on a first come - first serve basis, since the number of participants is limited. If you have any question(s) or need further clarification, you may contact us via lofarschool@astron.nl.

LOFAR Status Meeting

The LOFAR Status Meeting is joining forces with the community-based LOFAR2.0 Imaging Forum to establish a new series which will be of broad interest to the community. The meeting will have a monthly cadence. The first one took place on 15 October 2025, for which the recordings and presentations can be found on the slides repository. The audience is expected to be the broad LOFAR community, which includes researchers across all science areas and telescope modes, and the dedicated scientists and engineers who are working hard to enable this science. The format, which is limited to one hour, is:

• • short update on array status,
  • short news section on system updates,
  • a community-based talk, mostly science but some community development,
  • time for questions.

The program of the meeting for the upcoming year is currently being constructed. If you would like to give a community-based talk on a particular topic, or if you would like to nominate someone to give a talk on a particular topic, please fill out the following form:  https://forms.gle/LGt2Nf2DqYW8mAMv7. Note that you can use this form more than once if you wish to submit multiple (self-)nominations. The form will be available indefinitely for people to submit new topics, but the aim is to set up the program for the first several months as soon as possible.

LOFAR2.0 AIV and commissioning: Progress in delivering LOFAR2.0 stations (C. Baldovin, M.A. Brentjens, and the AIV and commissioning teams)

The upgrade of LOFAR stations in the Netherlands is taking place all throughout 2025. As of October 1^st, LOFAR2.0 hardware has been installed in all stations. After the installation is complete, they go through a series of checks: in situ and remotely. The rollout team checks all cable connections and the correct functioning of all equipment and sub-rack components. After that, the stations go through a verification process that can be performed remotely. The goal is to make a first check of the station processing capabilities. It includes specific settings, monitoring and control, connectivity, antenna status, crosslet statistics (XST), HBA and LBA polarity, beamformer performance and all sky imaging. The output of this process is an automated verification report that includes the result of each test and relevant information, such as possible antenna cable swaps and antenna status. The verification stops at station level, meaning that data transfer to the central processor (CEP) and science data products are out of scope, antenna repairs are not part of the upgrade activities, they are done as part of regular maintenance after the upgrade.

When a station is successfully verified, it is handed over to Telescope Operations. At this point, the Commissioning team takes over for further testing. The diagram in Figure 3 shows the progress in station verification from array release A (AR-A) until today; the check marks indicate that verification is completed (and stations have been handed over to Telescope Operations), the arrowed-circles indicate stations that are under testing. To this date ~25% of the LOFAR array has been verified. The verification of the Dutch array is expected to be finalized by the end of the year.

With the full Superterp available, and the CEP6 preprocessing cluster being installed, the commissioning team went ahead and attempted the first actual imaging runs, as well as tied-array pulsar observations (all still with LOFAR1.0 calibration tables). They demonstrated that the WhiteRabbit clock system works really well in keeping the inter-station delays constant to well within a nanosecond. Initial imaging of uncalibrated visibilities revealed a constant amount of mis-pointing of the tied-array beam: a little bit in HBA (Fig 4), but approximately a full superterp beam in the LBA (Fig 5).

The team furthermore discovered — and by now also understands — an issue with the pulsar data, where small unnatural dips occurred in pulsar profiles just before and after the main pulse. These observations mark a new phase in which we discover data properties that actually affect scientific outcomes: science commissioning is here! Over the coming weeks we expect to resolve the above issues and proceed with fully commissioning the tied-array mode. Parallel to that, as more stations are added, imaging quality is expected to rapidly improve, and to prepare for full NL-scale imaging commissioning by the end of 2025. The first dual-band LBA+HBA image of Cyg A was presented at the LOFAR Family meeting in Paris, demonstrating initial capabilities for one of LOFAR2.0’s main new observing modes (Fig 6).

We are happy to see several members of the wider LOFAR community already getting involved in commissioning over the past few weeks, and would like to invite particularly people interested in NL-scale imaging to contact Michiel Brentjens at brentjens@astron.nl to get involved too.

SDC Development Program  (J. Swinbank)

Work in the SDC Development Program over the course of 2025 has been sharply focused on getting LOFAR2.0 on-sky as soon as possible, and in a way that makes it accessible to and usable by the widest possible community. To that end, we have been making improvements and upgrades across our systems.

Highlights include:

• We've been steadily rolling out the new pipeline execution framework that we'll be using to orchestrate data processing in the LOFAR2.0 era. This is already up and running at SURF in the Netherlands (and has been used for LDV processing for some time) and is now also being commissioned at the LTA site in Jülich, Germany.
• The LINC pipeline is now runnable with the pipeline execution system in SURF.
• Upgrades are underway to the LTA to enable it to ingest the new and more advanced data products that will be generated by the Observatory from LOFAR2.0 observations.
• A system monitoring tool is being rolled out that will enable the SDC Operations team to keep much better track of what the LTA and other parts of the LOFAR data system are doing. In the short term, we aim to provide just enough visibility on the system to enable efficient operations, but we have ambitious plans for future expansion of this tool to provide a full-fledged operational control environment.

We have also been working hard on upgrades to the scientific pipelines being developed at ASTRON. LINC version 5.1 was released a couple of months ago, and brings a bunch of important improvements and upgrades. Full details are available in the release notes (https://linc.readthedocs.io/en/latest/changelog.html#version-5-1). We have also been hard at work on the Rapthor pipeline, with a major new release in April (https://rapthor.readthedocs.io/en/latest/changelog.html#version-2-0-2025-04-11) bringing improved speed and stability in addition to other new features; we are now preparing a Rapthor 2.1 release which will build on this success to deliver more improvements.

Finally, we have been planning for future improvements to the LOFAR data systems that we will be working on after the first version of LOFAR2.0 is ready. We're really excited about our vision for a “science platform”, which will be the main point of contact for all science user interactions with the LOFAR system, from submitting proposals to accessing data to running analyses — see the attached images for a preview of what we have in mind. We have also been preparing for much closer collaboration with SKA — both LOFAR and SKA are facing many of the same challenges, and both parts of the solutions. We think that by joining forces we will see some real breakthroughs over the next few years.