Upcoming changes to the production array configuration – M. Iacobelli

The production array will soon be missing two stations:

• The production array will soon be missing a station. CS001 will be handed over to the LOFAR2.0 team in Cycle 18 (formally on June 1st) until the end of the LOFAR1 operations. Details are provided below.
• CS032 will be handed over to a Space Weather team from April until June. After this period, an evaluation will take place to decide on the follow-up. The goal of the space weather test station is to demonstrate the basic concepts and tools for ionospheric and solar radio activity monitoring. The test station will provide proof of the observing capability and will help build the real-time database for testing the triggering and detection pipelines.

Because of these changes, all Cycle 18 proposals will be checked for the impact of the array changes on sensitivity.

New Science Website going live – C. Herbe-George

Sadly, after many years of service, our beloved old.astron.nl website has to retire. Worry not, the “website team” has been hard at work to deliver a suitable and hopefully more intuitive replacement. We’ve reshuffled, deleted and added webpages with the aim of making the site more user friendly such that everyone will be able to find the information they are looking for efficiently.

We still have a few polishing iterations to go and maybe a few bugs to fix but we’re confident the site will be ready to be released in June, in time for the LOFAR Family Meeting. Once released into the open web, we’d really appreciate all the feedback you have, be it organisational, feature- or content-related. This website is built for you, the user, and we'd love to make it as great as possible. Look out for the announcement!

• Currently, there are 38 stations operational in the Netherlands: 24 core and 14 remote stations, and 14 international stations in operations distributed across Europe: DE601, DE602, DE603, DE604, DE605, FR606, SE607, UK608, DE609, PL610, PL611, PL612, IE613, LV614.

• A new international station will be built in Italy. Station deployment is planned to start this year. The Italian station is expected to be fully operational in 2024.
• Antenna elements of all stations are performing nominally, except DE601 and UK608 LBAs, which were hit by flooding and stormy weather respectively a few weeks ago. They have remained offline since. RS409 LBA and CS005 HBA also have more than 15% non-operational elements. An overview of non-operational antenna elements for the LBAs and HBAs is available here.
• The storms that swept over Western Europe last month blew many tiles and antennas of several stations away, but they were attended to and put back into operations immediately, except the broken UK608 LBA, which will be fixed during the coming weeks.
• DE609 and PL610, especially the LBAs, have persistently shown low signal-to-noise ratio values for some time now: fixing the issue is on the list of the LOFAR maintenance team. The station owners have been asked to perform some checks in preparation.
• No major failures occurred on CEP hardware/software over the past couple of months.

• Cycle 17 observations started on 1 December 2021 and will run until 31 May 2022. The observing schedule can be found here.
• By the end of observing week 10, 53% of the observing program was completed, with an average observing efficiency of 67%. About 47 observing hours (representing 2% of production hours) have been lost mainly due to critical station unavailability and other system issues.

• Cycle 18 proposal call: by the end of the 9 March proposal submission deadline, 28 proposals have been received requesting a total of 1639.5 observing hours, 2759.9 processing hours and 1101.9 TB of storage space. These represent oversubscription factors of 2.78 telescope hours, 2.75 processing hours and 0.67 LTA storage space. The technical assessment of the proposals is currently underway, with a PC meeting planned to take place on 23 March 2022. The Cycle 18 observations will run from 1 June 2022 to 31 November 2022. The observing projects for Cycle 18 will include those that are accepted from the cycle proposals and the already running long-term projects from the previous cycles.

Telescope Manager Specification System (TMSS) - S. ter Veen

• The LOFAR observations are soon to be managed by TMSS, the Telescope Management and Specification System. TMSS will replace MoM as an interface for checking specifications. It has been developed over the past two years and we are very soon going to start running the first project with TMSS with more projects to follow in the coming months.
• Over the past months we have worked on scheduling, on combining beamformed and imaging observations, and most importantly, on validating the data and metadata, first for the LoLSS LBA Survey strategy. After a final validation step by ASTRON and the PI, the system will be ready to run the LoLSS survey in production. Development and validation will continue to accept all observing strategies (the LoTSS survey, pulsar timing, etc.) and add the user administration, dynamic scheduling and move reporting of daily observations from JIRA to TMSS. The goal is to run all Cycle 18 observations with TMSS, and, when ready, with dynamic scheduling. Switching from JIRA to TMSS for reporting will take place at a later stage.
• TMSS supplies one interface and an integrated process for specification, scheduling and reporting. It is also an update to modern web technology, which can relatively easily be expanded to support additional use cases such as COBALT2 and LOFAR2 stations and be interfaced with additional services. The system supports a selection of standard observing strategies, each requiring in itself only a minimal specification. A spreadsheet-type interface is available for a quick specification of many observations. A direct system interface will also be available for experienced power users for specification and for following the progress of their projects. Through dynamic scheduling and integrated reporting, we aim to optimise the operational procedures and make operations more efficient. The remaining time can then be used to improve the instrument further.
• Astronomers with active projects will be approached by Operations when their project switches to TMSS. Shared-support users will receive training on using the new system for their specification and checking of the data. Contact authors will receive information to check their specification, and, when ready, the reporting.
• Note for expert users on parset changes:
  LOFAR uses parsets for internal communication between processes and pipelines. We are aware that some expert users also use these to start their own processes. Please be aware that TMSS introduces minor changes, although they still adhere to the ASTRON parset standard. A summary of these changes can be found here.

LOFAR Development program – W. van Cappellen

LOFAR2.0 progress highlights are presented every two months in the LOFAR2.0 Newsletter, see: https://www.astron.nl/lofar2-0-newsletter/.

• In October, two information sessions were held to update the scientific community about the upcoming DUPLLO upgrade, as well as the progress of the development to date. At the same time, the call for expressions of interest was opened that will lead eventually to the DUPLLO Large Programme observing proposals. It was great to see about 140 people at the two sessions, which confirms the great scientific interest in DUPLLO. In December, we received 20 Expressions of Interest (EoIs) for the LOFAR2.0 Large Programmes. Together, these EoIs encompass about 200 pages of material from over 500 unique authors spanning the LOFAR partner countries and beyond.
• In November pre-production White Rabbit (WR) equipment was installed in a remote station (RS208). The idea was to use the same configuration planned for the final rollout and keep the station operational with the purpose of monitoring the behavior of the system over an extended period and spot malfunctions. As part of the program, we did a test observation of 8 hours. The figure below shows a series of plots for four different stations. Three of them (RS106, RS305 and RS306) with the current LOFAR clock system and one with WR, our pilot RS208. The graphs show the clock offset with respect to the core stations during an 8-hour period. If you note the scale of the offset (y-axis) in the different plots, the improvement achieved with WR becomes immediately evident, with an offset smaller than 0.6 ns during the 8-hour test. By comparison, the current LOFAR system shows typical variations of 10-20 ns per 8 hours. This result gives us further confidence that we will improve the clock accuracy for the LOFAR stations in the Netherlands thanks to WR.

• A lot of work was put into the testing and documentation of the LOFAR2.0 Station hardware. The measurement campaign included long-duration tests, EMC tests, thermal tests, and RF performance tests. So far, the verification has been successful. An EU public tender will be published shortly to produce the series hardware.
• The LOFAR2.0 monitoring and control software is steadily progressing. The Jupyter notebooks and Grafana dashboard that have been set up have been extremely useful for the testing and debugging of the subrack boards. The notebooks provide a user-friendly and highly automated environment to run tests and store test methods and test results consistently. This feat is possible only through the effort that the software team has put into setting up a Tango framework that connects the notebooks with the system translators, which in their turn communicate with the hardware. It is exemplary for the level of integration that has already been achieved at this phase of the project.
• From June, CS001 will be used as a test station for LOFAR2.0 hardware. The goal of the test station is to lower risks in the rollout phase. It will be the first full-scale LOFAR2.0 Station with all newly developed components fully integrated. This will enable the development team and Operations to verify and validate the LOFAR2.0 Station design, at the required scale and in an operational environment. Gaining operational field experience, and to integrate and test together with LOFAR1 shortens the validation time in the rollout phase. The test station is the most realistic test and development platform possible. To allow this, the LOFAR1 hardware in the test station will be replaced with LOFAR2.0 pre-production hardware.
• The last batch of HBA-FE boards (the main electronics board in the HBA tiles) is being manufactured at this moment. Component obsolescence makes it impossible to purchase additional boards after this round. With the boards to come we can secure regular maintenance for a couple of years. In April, a redesign is starting to secure the maintenance in the future and the rollout of new single-beam stations. The project will initially deliver a single-beam version. If sufficient funding is secured, the project will proceed and deliver a dual-beam version of the HBA tile as well.
• Brian Hare (RUG/ASTRON) received a prestigious ERC Starting Grant for his lightning research using LOFAR. His grant includes the reinstatement of the transient buffer functionality in LOFAR2.0. This is excellent news for lightning research and other use cases that use LOFAR's transient buffers.
• It was decided to implement a connection between the NenuFAR antennas and the French LOFAR station. This will enable LOFAR users to benefit from the huge collecting area of NenuFAR.
• The ICT support of the CEP4 cluster ends on September 1, 2023. The first steps are being taken towards CEP6.

Science Data Centre program – J. Swinbank

• The Science Data Centre Program team has completed a major upgrade of the Prefactor pipeline, which provides direction-independent calibration and imaging for LOFAR. This pipeline is now described using the Common Workflow Language¹, which makes it possible to integrate the pipeline with the execution system that is now being used to do processing for the LOFAR Data Valorization project. We expect this to become the standard mechanism for carrying out data processing within the SDC in future. This will enable the SDC Operations team to begin offering Prefactor processing to the community as a service.
• The SDC Program team has been pressing ahead with the development of ADEX, the ASTRON Data Explorer. Building on the work we’ve done in the ESCAPE Project², ADEX is intended to provide a friendly and accessible portal for discovering and accessing the various data holdings available through ASTRON’s SDC Facility. Our aim is to achieve an initial operational capability which is limited to accessing data available through virtual observatory interfaces³ towards the middle of this year, with a possible extension to the complete LOFAR LTA in the future. Figure 1 shows an example of some of the work that is currently in progress.
• The SDC Program team collaborated with our colleagues in the LOFAR scientific community to publish LoTSS DR2⁴ through the Data Repository at SURF⁵, the Dutch National e-infrastructure provider. While this data release is a major scientific achievement and we are delighted to have been able to contribute to its release, this is especially notable from the SDC development perspective as it demonstrates both the form of rich scientific data repository that we expect to increasingly support in the future and the benefits of close cooperation with the outstanding technical team at SURF. Figure 2 shows the LoTSS DR2 repository.
• The SDC Program team has been deeply involved in planning for the SKA Regional Centres (SRC) network over the last several months. In collaboration with our partners in the worldwide SRC development effort, we have developed an extensive set of requirements, are cooperating to design a supporting architectural vision, and are about to embark upon a substantial prototyping effort. Although it will be several years before the SRC network is available for general use by the scientific community, we expect this work to point the way towards possible future evolution of the data services supporting LOFAR.

LOFAR Data Valorization – E. Orru

During the last months, the LDV team has made progress in several aspects of LDV-phase 1.

Concerning the data processing at SurfSara, work is in progress for:

• implementation in the production environment of tooling needed to enable operational procedures;
• documenting the operational procedures;
• implementation of quality metrics for the “compression workflow”. This will enable validating the LTA processing and setting / exposing quality indicator flags per dataset;
• implementation and testing of the ‘Prefactor workflow’.

The operational phase of the ‘compression workflow’ at SurfSara is expected to start in April. Next, we will focus on starting with the production phase at the other LTA sites. To this aim, the characterization of the LOFAR data collection content at the Juelich and Poznan LTA sites has been accomplished. In concert with the LTA partners, the implementation of the processing workflows started in Juelich. Moreover, an initial assessment in terms of hardware requirements and human resources is being made to enable the start of the LDV processing at the Poznan LTA site.

LOFAR Family meeting – H. Volker (LOC chair)

The LOFAR Family Meeting 2022 is a gathering of LOFAR enthusiasts happening in Cologne (Germany) during 13-17 June 2022. A selection of invited and contributed talks will cover the main science areas of LOFAR including:

• Surveys and Methods
• Pulsars and Interstellar Medium
• Extra Solar Planets
• Sun, Space Weather and Cosmic Rays
• Epoch of Reionization
• Active Galactic Nuclei
• Galaxy Clusters
• Milky Way and Nearby Galaxies

In addition, there will be extra sessions for a LOFAR Users Meeting and a presentation of LOFAR2.0. There will also be the opportunity to present posters.

The draft program, registration and abstract submission can be found on the conference web site: https://www.glowconsortium.de/index.php/en/lofar-family-meeting-2022

In case of any questions please contact the conference organisers via: lfm22@physik.uni-bielefeld.de

We look forward to seeing you in Cologne this summer!

ERIS 2022 – M. Iacobelli (on behalf of the LOC)

The 9th European Radio Interferometry School (ERIS 2022) will be hosted by JIVE and ASTRON in Dwingeloo (the Netherlands) on 19 - 23 September 2022. ERIS 2022 will provide a week of lectures and tutorials on how to achieve scientific results from radio interferometry.

The topics covered by the lectures/tutorials will include:

1. Calibration and imaging of continuum, spectral line, and polarization data.
2. Low frequency (LOFAR domain), cm-wave (e-MERLIN domain), decimetre-wave (HI/OH domain), high frequency (ALMA/IRAM domain), and VLBI interferometry.
3. Extracting the information from astronomical data and interpreting the results.
4. Choosing the most suitable array and observing plan for your project.

Registration for the School is currently open and the deadline for registration is 15 May 2022. The number of participants is limited to 85. We strongly encourage the potential candidates to proceed with the online registration as soon as possible.

The dates of LOFAR Status Meetings, roll-outs and stop days are listed in an online calendar that is available here.

The next LOFAR bulletin will be issued in August 2022.