End of LOFAR1.0 production operations

The Cycle 20 observing campaign officially ended on August 31, 2024. This date marked also the last day of over a decade of LOFAR1.0 production operations and the shutdown of the telescope to make way for gearing up the LOFAR2.0 telescope upgrade. The exciting stories of the 12 years of LOFAR1.0 telescope operations are summarised here.

LOFAR2.0 commissioning

Commissioning of the LOFAR2.0 telescope is ongoing. We have identified three main commissioning areas (telescope, pipelines and operations). The community has the opportunity to join any of the working groups where their expertise can contribute to commission different aspects of the observing and processing system. There is a public Confluence page dedicated to these commissioning activities with links to the different commissioning teams where people can still sign up and join. Exciting discussions on various topics are already happening in the working groups. See Commissioning towards LOFAR2.0 on-sky, for commissioning updates. In case of issues, please request access by contacting the SDC-Helpdesk.

Report on LOFAR2.0 data processing busy week

The LOFAR2.0 data processing and management busy week took place at ASTRON (in Dwingeloo) during October 21-25, 2024. The participants included the LOFAR2.0 Large Programs PIs and several other people involved in the development of services, functionalities and workflows that will be needed for the LOFAR2.0 observing program. Various working groups were formed that discussed and agreed upon various aspects of the functioning of the LOFAR2.0 Observatory. These included: LOFAR Observatory structure and processes, supported modes, data products and ICD (Interface Control Documents) and pipeline development processes. The outcome of the Busy Week will be a document capturing the LOFAR Observatory Management plan, to be submitted to the LOFAR-ERIC council for endorsement. A summary of the report of the busy week has been given at the LSM on 30 October, and can be accessed here.

Data staging and downloading from the LTA sites

Data staging and downloads from the LTA sites were generally stable in the past few weeks, except for the few planned maintenance days that the services were unavailable. Planned maintenance days are always mentioned at the LTA portal. Contact SDC-Helpdesk if you experience any issues with staging and downloads.

CEP infrastructure upgrade

In preparation for LOFAR2.0, the CEP (CEntral Processing) infrastructure gets almost completely overhauled and renewed. This includes the network connection, and the CEP4 and COBALT2.0 clusters. The main LOFAR 10 Gbit/s hardware network infrastructure from 2008 has already been replaced with a modern 400 Gbit/s network. The COBALT2.0 correlator (from 2018) and CEP4 processing and storage cluster (from 2015) will be upgraded to COBALT3.0 correlator and CEP6 cluster respectively. More details about the CEP upgrade can be found in the latest LOFAR Development Newsletter.

• New international stations will be built in Italy and Bulgaria in the coming years. Both stations will be equipped with LOFAR2.0 hardware; whose installation and rollout are expected in 2025.
• The LOFAR1.0 Dutch stations are currently shut down and are not being used for production observations: they are being upgraded to LOFAR2.0 stations status. At the moment, CS001, CS032 and RS307 have LOFAR2.0 hardware installed. The international stations still with LOFAR1.0 hardware have been handed over to the stations’ owners for their own science programs.

Erratum: In the previous edition of the LOFAR Newsletter (i.e., August Newsletter), we stated that 49.0% of the LBA elements at the French station (FR606) were non-operational during the period April - June 2024. This statement was misleading. At the time, FR606 was configured and reserved for NenuFAR commissioning observations. The LBAs were in good condition, but they were not available for standard observations, which led to their erroneous flagging. Both the HBAs and the LBAs elements of FR606 are operational and working as expected.

• Cycle 20 observing campaign started on 1 June 2023 and was supposed to finish on 31 May 2024; it was extended and finally closed on 31 August 2024. The LOFAR-ERIC Board approved a three-month extension to allow the completion of observations of the allocated production cycle projects, DDT, ORP and NenuFar commissioning on best effort and shared risk basis.
• The 15-month long observing campaign of Cycle 20 ended with a weekly observing efficiency of 60%, telescope observing efficiency of 73% and completion level of 97%.
• As mentioned earlier, the LOFAR observing system was shut down on August 31, 2024, to give way to the system upgrade to LOFAR2.0. Therefore, no observing campaigns are currently ongoing. The next production observing campaign will be the LOFAR2.0 early cycle science commissioning and shared risks observations.

LOFAR Development program (W. van Cappellen)

• LOFAR1 has been switched off! This may sound contradictory, but this milestone allows us to prepare the telescope for the arrival LOFAR2.0 early next year. CEP4, COBALT2 and the core network are being reconfigured such that they can be used for LOFAR2.0 commissioning. In parallel, a European public tender for the procurement of COBALT3 and CEP6 was completed. The first COBALT3 hardware is expected to arrive by May next year.
• Another major milestone that was achieved is that the LOFAR2.0 Production Test Stations are up and running and all LOFAR2.0 hardware designs have been released for production. Even better: The first batches of UniBoards have been delivered. The rollout of the LOFAR2.0 stations is now getting physical! The transition to LOFAR2.0 is also becoming very visible in the LOFAR Control Room at ASTRON. The big displays now show the station of the first three LOFAR2.0 stations using the new Grafana-based dashboards.

SDC program (J. Swinbank)

• A major focus of the SDC development team over the summer has been the new proposal tool TULP, set to replace Northstar for LOFAR2.0 operations. This is a much more modern and accessible tool, which integrates better with the rest of the LOFAR system, and which is much more flexible and extensible to support a range of observing modes. We think it looks pretty great too — see the image below.- In parallel with the above, the team has continued to work on an upcoming release of the LINC direction-independent calibration pipeline which will provide support for observing with the LOFAR LBAs. Watch for news at https://linc.readthedocs.io/.
• Finally, we have made some major performance improvements to the Rapthor direction-dependent pipeline. Look for these to be made widely available in an upcoming release which will be made available at https://rapthor.readthedocs.io/.

Commissioning towards LOFAR2.0 on-sky (M. Brentjens, R. Pizzo, Carla Baldovin, Cees Bassa, Marco Drost, Boudewijn Hut, Marco Iacobelli, Emanuela Orru, and Tim Shimwell)

• For up-to-date information about the status of commissioning, have a look at the public confluence page.

• The summer was spent on cleaning up the DUPPLO/LOFAR2 requirements database, and to observe as many legacy data sets with LOFAR1 as possible. This includes observations of most "A-team" sources, RFI environment measurements, and data sets to compare the new White Rabbit time base to the previous LOFAR clock. With LOFAR1 permanently shut down as of early September, the commissioning teams are busy writing test plans for all experiments that can be performed during array release B (three stations ready, ability to cross-correlate and beam-form, and writing data to a reduced CEP4). We expect to reach this milestone soon. To facilitate writing good test plans and homogenize effort estimations, weekly test-plan-writing sessions are organized by the Telescope and Operations commissioning teams.
• We have created a Frequently Asked Questions (FAQ) page where you will find answers to the most common questions about LOFAR2.0 commissioning efforts. If you cannot find the answer you are looking for, feel free to submit a question using this form and we will answer it on the FAQ page.