LOFAR2.0 is more tangible than ever. The first complete test station is a fact, white rabbit hardware has been delivered, and the call for proposals has been published!
In June we had the LOFAR Users Committee (LUC) meeting and I visited the LOFAR Family meeting in Olsztyn, Poland. It was great to see the enthusiasm about LOFAR and LOFAR2.0. It was also valuable to talk to people in-person about they wishes, our plans and how they can help.
LOFAR2.0 is in the middle of the integration and verification phase; An exciting and intensive period! For the first time we are building a complete LOFAR2.0 station to test whether everything works as expected and all issues must be solved. At the same time, there is time pressure to deliver the final designs for the production of the rollout hardware. Big compliments to everyone involved. You are doing a great job! Meanwhile, we are busy setting up the plans for the LOFAR2.0 rollout and commissioning phase. We have interviewed people who have been involved in this phase in LOFAR1 and Apertif to learn as much from their experiences as possible. It is clear that strong teamwork and organizational support will be essential for its success. You are a super team, so I am confident that this will work out.
Happy reading and enjoy the summer!
The call for LOFAR2.0 Large Programme proposals has now been launched via a new LOFAR website (www.lofar.eu) that is also standing ready for the evolution of the International LOFAR Telescope to a European Research Infrastructure Consortium (ERIC) – hopefully later this year. After previously receiving 20 Expressions of Interest (EoIs) for the LOFAR2.0 Large Programmes, we expect a large number of full proposals on the October 12th deadline. We are also encouraging the EoI teams to actively discuss their plans and to look for ways to merge into a few Large Programmes each of which can serve many science cases. The recent LOFAR Family Meeting in Olsztyn, Poland (http://lfm2023.uwm.edu.pl/) featured a LOFAR2.0 & Users Session to stimulate such discussions. Those discussions will be continued in the coming months via several more online workshops. The proposal teams are being asked not only to motivate their science goals, but also to provide clear plans for analysis and publication. They are also being asked to demonstrate that their research teams are inclusive and provide opportunities for new members to join the broader LOFAR community of scientists.
LOFAR currently operates with 15 years old network equipment. Furthermore, also the CEntral Processor equipment is nearing the end of support term. Therefore, all of those systems are planned to be upgraded in the near term in a phased approach as is depicted in Figure 1. The top line shows the roll-out schedule of the LOFAR2.0 stations. In the year 2024 we move from the LOFAR2.0 Test Station (L2TS) to 3 so-called Prototype Test Stations (PTS). From late 2024 production stations will be rolled out.
The second line of Figure 1 shows the procurement of the new network equipment and the dismantling of the present network equipment. The new network is built in parallel with the current network equipment, which is shown in Figure 2. As soon as new LOFAR2.0 stations are in the field they are connected via the new network equipment, while the data is still transported to the current CEP systems (mainly Cobalt2.0 and CEP4) via a conversion layer. Therefore, the number of stations connected to the present network will gradually scale down at the same pace as the number of stations to the new network is scaled up. In the third line of Figure 2 can be seen that the CEP procurement is done after the network procurement and broken up into phases. Instead of building the complete CEP in a big bang fashion, with the risk that the capability is not sufficiently used because not all LOFAR2.0 stations are available, multiple phases will be used. In that way CEP ramps up gradually and is tailored to the needs of that time. The goal is to keep doing that in the future as well in case the first purchased hardware becomes obsolete.
At first, the LOFAR2.0 stations will be commissioned with the current CEP systems. As soon as the renewed CEP systems become available, they will be used for commissioning. The “cross-fade” period in between allows for sufficient time to iron out issues or “unknowns” with the renewed CEP system. The bottom line shows the timeline of operating and commissioning the telescope, wherein this “cross-fade” is clearly visible.
Let me start with some great news: we are moving the LOFAR2 Test Station Phase 2 (L2TS-2) to Exloo during the first week of July. How did we get to this point? Read on!
The long-awaited receiver units (RCU2) arrived and were tested thoroughly with the test setup that was built during the preceding months. We solved the issues we could and put workarounds in place for those that could not be eliminated in our lab.
We produced the splitter PCB, the cabinet clock distribution unit, and its casing in house.
Our mechanical engineers filled the three subracks with all the equipment and we started the very dynamic process of executing our lab test plan. It is “all hands-on deck” to find the causes of issues and to solve them on short notice. Any updates needed on our computing boards, mechanical or other designs are noted and will be implemented before the next prototype test station (called the Production Test Station or PTS) is built.
Now we are finishing the last tests and reviewing our checklists to make sure that everything is in place for the impeding rollout.
Stay tuned for the first results from the field!
Production of the first AHBAFE prototypes started at ASTRON; this consists of the integration in a single board of the different blocks that were previously prototyped and tested.
The current version of the board has more than 1000 components, most of them are placed by a “pick and place” machine but about 300 need to be placed by hand. The first prototype was produced taking the time to test each block in the process. During the first production run, we are looking at possible errors in the layout and at reducing the number of unique components.
Tests done on the new AHBAFE include gain, output impedance, beamformer accuracy, noise, linearity. The results obtained so far are encouraging; when tested against temperature variations and compared with the current LOFAR frontend boards show an improvement of a factor of ~4 in phase and ~15 in amplitude.
During the coming months we will continue producing frontend boards (up to 16) to integrate a full HBA tile that will be used to further test the performance of the AHBAFE. After this step, a small production of 80 boards will be outsourced to an external manufacturer.
The first batch of White Rabbit switches was delivered to ASTRON the third week of June; now the team is preparing the hardware to start installing it in the field.
The new timing distribution system will be installed in all LOFAR stations in the Netherlands; the upgrade will be done in 2 phases: the first one will only touch the remote stations and will be completed this year. During the second phase the core stations will be upgraded.
Each remote station has an independent clock; therefore, they can be upgraded incrementally and without disrupting normal LOFAR operations. After the installation of the White Rabbit switches in each station, we will perform verification and validation of the system. After successful completion of the tests, the stations will be put back in operation.
Since core stations are connected to a single clock via the Syncoptics system, they will be upgraded at the same time as the rest of the LOFAR2.0 upgrade.
The image shows the configuration of the connections, green ovals represent core stations, yellow and pink ovals represent the remote stations.
One of the major challenges of the LOFAR support staff is to fill the LOFAR telescope calendar efficiently with approved observation programs. The scheduling process has to take into account many parameters, such as project priority, source visibility, antenna availability, maintenance activities like mowing and repairs and many more, sometimes unexpected, events.
Needless to say, that this puzzle creates a heavy burden on the Observatory staff responsible for carrying out the observing program. To alleviate that burden, automating the scheduling process has been one of the major requirements for TMSS. The functionality for this was named the “Dynamic Scheduler”. Dynamic, because it allows an operator to rerun the scheduling process whenever a constraint changes. This can be a station dropping out, a trigger caused by an event that requires LOFAR to observe that target of opportunity, or some other event that changes the capability of the telescope.
After a long period of extensive testing, the important decision was made to start using TMSS fully, including the dynamic scheduler, for LOFAR observing cycle 20 which started on June 1st. This decision is a major milestone for the TMSS team and the dynamic scheduler.
The Dynamic Scheduler will relieve the burden on everyone involved in the day-to-day planning of LOFAR observations. The first production period, starting on June 1st, helped us to iron out a few remaining issues. Overall, it works well without any showstoppers and the supporting staff is getting used to it quickly. A bright future lies ahead!
In the figures we show some of the plots that are part of the automated scheduling process. They show a day-schedule for LOFAR, resulting from automatically scheduling a batch of observations, and a few plots showing the ‘goodness of fit’ of some of the scheduled observations, with respect to the constraints that these observations should adhere to.
With TMSS and the Dynamic Scheduler now in full production mode, we are looking forward to extending the scheduler to include other, new constraints such as, for example, the state of the ionosphere which has a major impact on the data quality of a low-frequency radio telescope such as LOFAR (comparable to optical seeing for a visible-light telescope). With TMSS we are looking forward to improving the usability and responsiveness and including all requested observing types of Cycle 20.
Eric Kooistra is still working on the design of the required firmware functionality for LIFT. An internal review of the design documents will take place at the end of July.