© ASTRON

The RadioHDL package consists of a rich set of scripts that automate and ease the code development for FPGAs. We have used and are using RadioHDL for UniBoard1 in APERTIF and ARTS and UniBoard2 in ARTS and LOFAR2.0. The name RadioHDL reflects that it was first used for HDL (Hardware Description Language) code development in FPGA projects for Radio astronomy, but these scripts can be of use for other FPGA projects as well. Currently CSIRO also uses RadioHDL for the Gemini board in SKA CSP Low.

To publish the RadioHDL package we followed the ASTRON Open Source Policy (DOI: 10.5281/zenodo.3479834). This policy includes using the Apache 2.0 license and a Digital Object Indentifier (DOI). The DOI that we obtained via (Zenodo) is:

RadioHDL DOI: 10.5281/zenodo.3631361

This package is one of the first pieces of software that ASTRON has published with a DOI. We are proud that RadioHDL is now ready for download and to be referred to.

© Henk Mulder, Jurjen Sluman, Richard Blaauw, Paul van Dijk, Menno Norden, Lute van de Bult, Peter Gruppen, Marco Drost

© Peter Maat

After three years of DISPERSE technology development, the project ended on Friday, January 31 2020. The last DISPERSE event was the final review meeting at Leuven. The reviewer team was very enthusiastic about the outcomes of the project and rated the project as excellent. The technology that ASTRON and project partner Technobis developed in DISPERSE was shown during the meeting in a demonstration setup. The picture at the left shows Leon and Lesley and the demonstration setup during the DISPERSE meeting in Leuven. A picture of the integrated electronic/photonic component is given at the right-hand side, showing a photonic transmitter IC surrounded by a PCB with two laser-driver ICs. The PCB was designed by ASTRON while the assembly of the module and fibre-optic pigtailing was performed by Technobis. DISPERSE project leader Mark van Helvoort made a number of movies about the DISPERSE results that are available via his Youtube stream. Two of them concern the ASTRON application (see: this movie).

© ASTRON/NWO

One commonly used interface in industrial automation is the OPC Unified Architecture (OPC-UA). This is a well-developed standardized protocol with many interesting and advanced features that can be the basis of all internal and external LOFAR2.0 station interfaces. See Wikipedia for a nice introduction and further references. Using OPC-UA , we can implement the monitor and control interfaces of the new LOFAR2.0 station much more easily and much faster. Knowledge transfer about these interfaces is much more trivial, and changing components for newer versions is less problematic and time intensive.

To demonstrate the ease of use of OPC-UA, we created a small prototype setup. Thijs Snijder (graduate student at DESP) and Leon Hiemstra used a power module board from a Uniboard that provides, among other things, temperature sensing. To export the temperature data, Thijs installed an out-of-the-box OPC-UA server, provided as a Python library, on a Raspberry-Pi. The Raspberry reads out the chips' temperatures using PMBUS, an I2C based protocol, and provides this data to its OPC-UA python server program. The OPC-UA server can then be connected to, over the network, with any OPC-UA client installation to obtain these values.

To read out the exported values from the Raspberry, and display the measured temperature values, Arthur Coolen used the WinCC-OA SCADA system (also used in LOFAR and Apertif). The WinCC-OA system has built-in OPC-UA client support which allows discovery of available OPC-UA servers on the network and retrieval of their data fields. Furthermore, WinCC-OA stores the acquired data it in its internal database and can display the  values in graphs on a screen. All this functionality could be setup and demonstrated in a matter of hours, instead of days to weeks were we to program all the involved steps ourselves. And this was just for a first attempt...!

We show that with very little effort, and using the right tools, we can setup industry-standard monitor functionality using OPC-UA as the middle layer between the real hardware and our monitoring software. This offers a glimpse of what we can achieve using OPC-UA in LOFAR2.0 as a whole. 

© ASTRON

We experimented with this toolkit, for research purposes and to evaluate its practical suitability for future FPGA application development. We developed an OpenCL Board-Support Package, that allows us to run OpenCL applications on a UniBoard2 (top-right image). We also developed an OpenCL application that filters digitized samples from a LOFAR Low-Band Antenna through a PolyPhase Filter bank. The filter consists of an array of FIR filters and an FFT (bottom-left image), functionally similar to the filter at the LOFAR stations. Then, the program sends the output data in UDP packets over a 40 Gb/s fiber to the DAS-5 computer cluster, where we capture the packets on a regular server machine. The bandpass of the LOFAR antenna (top-left image) demonstrates that the high-level programming approach works, at least for rapid prototyping. We now investigate if the programming environment is suitable for production-quality applications, such as the LOFAR 2.0 station firmware.

This is not the first success of the Triple-A 2 and DEEP-EST projects, through which we explore high-level programming of FPGAs. Earlier, we successfully implemented the Image-Domain Gridding imaging algorithm on an Arria 10 FPGA. A paper that compares CPU, GPU, and FPGA imaging received a best-paper award at the Euro-Par'19 conference (bottom-right image). A big thanks to our funding agencies (NLeSC, EU)!

© Robert Main

from timing observations. I will then describe efforts towards a more ambitious idea; once one solves for the distance and geometry of the scattering screen, the interfering scattered images can be used as an interferometer to study pulsars with ~100km precision. This method can be used to probe pulsar emission regions and to resolve a pulsar's binary motion, and I will show an early look at LOFAR data taken in the last few months towards this goal.

© The LOFAR-EoR project

In a new publication, the project presented the deepest upper limit on the 21 cm signal power spectra at redshift z ~ 9.1, using 141 hours of LOFAR observation of the North Celestial Pole (NCP). The analysis includes significant improvements in calibration, notably in handling direction-dependent effects, and improvements in our foregrounds mitigation and power-spectra extraction methods, leading to a significantly deeper limit on the 21 cm signal compared to our previous analysis (Patil et al. 2017).

The left plot shows the LOFAR-HBA Stokes I continuum images (134–146 MHz) of the NCP field. The right plot shows the current best upper limits of several 21-cm Epoch of Reionization experiments. The new LOFAR upper limit is the deepest observed at redshift 9 and is an improvement by a factor 8 in power compared to the previously reported upper limit. The team is currently busy implementing new improvements in the processing pipeline with the aim to reach the level predicted by theoretical models. This effort is also critical to ensure the success of future observation of the Cosmic Dawn and Epoch of Reionization with the SKA. In an accompanying publication, the team also attempted to constrain the state of the Inter-Galactic Medium at this distant era.

Arxiv Links:

Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at z≈9.1 from LOFAR

Constraining the intergalactic medium at z≈ 9.1 using LOFAR Epoch of Reionization observations

© Odysseas Votsis, Jorrit Siebenga, David Prinsloo (text) / ASTRON mechanical dept. (images)

As with many things, the increased bandwidth does not come free. In addition to the electromagnetic design challenges, the feed-network of this sinuous antenna presented some unique manufacturing challenges. This design required a three-section uniform taper impedance matching network implement in an air-core quadraxial transmission line. (Try saying that three times fast.) As the remainder of the images show, the design dimensions pushed the boundaries of our lathing manufacturing process (notice the stepped diameter of the vertical copper rods). Despite the manufacturing challenges, ASTRON’s mechanical workshop successfully designed and built the full setup according the required specifications.

Ultimately, this work demonstrated the feasibility of a wideband single pixel feed on the WSRT, achieving more than 50% aperture efficiency (simulated) over the frequency band from 1 GHz up to 8.5 GHz.

© TMSS team

This is being realized by a team of software engineers and telescope scientists (see picture) who are very committed to make the project a success.

By the end of 2020, TMSS will deliver with high priority the software components for executing the LOFAR2.0 Survey Use Cases. By doing that, the project will implement also other LOFAR Science Use Cases, which will ensure a healthy continuation of the Cycle observing programs also before the start of the LOFAR2.0 surveys.

The TMSS project started in January 2020. During its first quarter, TMSS will implement the system foundations in terms of telescope model and database. Additionally, it will deliver a system capable to perform the survey observations with the required handling of and feedback on system resources. The following cycles will implement dynamic scheduling functionality, support for the other planned use cases and responsive telescope functionality.

TMSS is an important component of the Telescope Manager of LOFAR2.0, the system that will control all aspects of the telescope, including proposal handling, observation execution, and system monitoring.

© Francesco de Gasperin

However, in some sense, these sources are real monsters. Their names are: Cassiopeia A (top left), Taurus A (top right), Cygnus A (center), and Virgo A (bottom). These are the four most powerful radio sources in the northern hemisphere. Historically, the brightest radio sources in the sky were named after the constellation in which they were found followed by a letter starting with an “A”. They were then grouped in the so-called A-team, like the famous TV series from the 80s. In this image we show their radio emission as seen by LOFAR LBA at 54 MHz.

The nature of these four sources is very diverse. The eyes of the monster (Cassiopeia A and Taurus A) are two supernova remnants: the leftovers of the explosions of two stars in our own Galaxy. The evil pupil that stares at you in Taurus A is the Crab pulsar. The nose of the monster, Cygnus A, is an extremely powerful radio galaxy 600 million light years away, whose two lobes are powered by jets of energetic particles formed near a supermassive black hole. The mouth of the monster (Virgo A) is the extended structure (larger than an entire galaxy) that surrounds the famous supermassive black hole at the centre of the galaxy M87, the same black hole recently imaged by the Event Horizon Telescope.

Reference: de Gasperin et al. A&A in press

© Christian Fendt

I will start 0) with an introduction on the basic physics involved. The image shows these simulations (GR-MHD).

© ASTRON

Initially she started in the canteen, she successively worked as administrative assistant, secretary and employee events & secretarial support, she eventually became secretary of the general affairs department.

A few years ago, she became responsible for the service level in the guesthouse. She does her utmost in order to make our guests in the guesthouse feel welcome.

As we all know, Ina is always willing to assist when this is needed and is really creative in designing badges for events or custom made get well cards for colleagues. She knows a lot of ASTRON's history and also remembers many former colleagues.

So Ina, congratulations with your 25th anniversary and thank you for everything you have done in all those years!

© Alex Benjamins

The government has made legislation that companies must comply with. This starts with classifying the buildings according to an energy label. By 2023 buildings must have the energy label C, and by 2030 the buildings must have energy label A. ASTRON has recently received energy label A for its buildings in Dwingeloo.

In addition to the energy label, the government sets efficiency requirements. For example, cooling and heating installations need regular inspection, and certain parameters must be met in the field of emissions. Besides, performance data of the cooling and heating installations need to be recorded and will be sent to the right authorities. The energy usage is playing an increasingly important role in business operations, saving energy means saving money.

In 2014, ASTRON put into operation a cooling and heating storage installation, with which cold water is extracted from the ground for the cooling process in the summer, this is returned to the ground as "warm" water. In the winter, the process is reversed, and the hot water is used to heat Building 80 and 2012.

In order to know where our electrical energy is being used, we have installed several kWh metres last year, including the server room, and we can now monitor the consumption per server rack in detail. (The metres are used to monitor the load on the groups as well.)

We have placed all measuring points in an energy overview so that we can not only read the information from tables but directly see the relationships between a number of parameters.

The consumption of heat, cold, gas, electricity and water per building is made visible. We can easily monitor ASTRON's legal obligations to the right authorities every month and, linked to the cost price of the various energy carriers, the costs of our energy consumption.

Further, we keep track of the effectiveness of certain processes. So that any deviations can be detected. This overview is made every month and an annual overview is kept.

Do you have any questions? We are always happy to provide an explanation of our overview. The complete overview is in the canteen.

© The NenFAR Cosmic Dawn KP

The animated image shows Stokes I 40x40 degrees images centred on the North Celestial Pole as seen by NenuFAR at four frequencies ranges. For comparison, an AARTFAAC HBA image at 122.1 MHz produced by Bharat Gehlot is also included. The current 400-meter maximum baseline of NenuFAR limits the resolution to 1.2 degrees at the lowest frequency and 0.5 degrees at the highest frequency. The upcoming addition of remote mini-arrays to NenuFAR will push the resolution down to 4 arcmins at 85 MHz. Despite the very different resolution and Field of View, the similarities in the images are striking. The smallest baselines were included in making these images at which large-scale diffuse Galactic emission, clearly and consistently seen in these images, starts to dominate. Modelling and including this diffuse emission in the calibration sky-model can significantly enhance the calibration of the instrument.

© ASTRON

ASTRON will strive to continue LOFAR science observing to schedule. Users should be aware that operations are running remotely, but debugging and general support will not be as timely as you would normally expect from us.

ASTRON will strive to continue Dutch station maintenance. But there will be no international station maintenance visits until further notice. Participant visits to ASTRON, JIVE or Dutch partners is not possible.

WSRT operations will run uninterrupted.

JIVE operations are expected to continue as normal.

If you have any questions, you can send an email to info@astron.nl. We hope you and your families stay safe.

© .

© AO + JvL

As currently only dust and tumbleweeds gather in this corridor, I was very glad to be allowed to cry out in a less physically real environment, this morning: at the first virtual AG coffee (see image). It went surprisingly well! Pets, work, family, corona, old and new plans, all the same topics as a normal Wednesday AG coffee. Just one thing was absent --

Funny how one misses yellow cake.

© Mechanical department

© JvL

During observing weeks for the FRB survey (ALERT), the slack channel is very lively. The astronomers, both those on duty and the rest of the team, are poised to immediately analyze any new FRBs that our system detects in real time. Last weekend was a blast. On Saturday night we found an FRB with a very high dispersion measure (#1 in the image). Yet another one on Sunday evening (#2), and when we were all trying to take a breath from the data analysis, and from follow-up observing and calibration way after midnight, we discovered a third one on Monday morning (#3). Three FRBs in three days is a new record!

All three are from significantly farther away than those we detected when the survey started; these new FRBs went off 5-7 billion (!) years ago. They were emitted before the Earth and Sun even existed, and traveled all this time, but still last only about 1 millisecond; then hit Westerbork on the weekend. FRB Party.

© ASTRON / CSIRO

All interfaces to the Gemini-XH can be remotely accessed, we can program the FPGA, have access to the control interface to monitor all the internal sensors. We have even added a remote power ON/OFF switching mechanism to power cycle the board. To keep in touch with the board we have set up a webcam in the Astron laboratory, as can be seen in the image.

On March 23th we started a high-power test, which has run successfully through the night. The power consumption of the complete Gemini-XH board was 260 Watt, of which about 70% is used by the FPGA. Even with this high power consumption, and current exceeding 150 A, the FPGA temperature did not exceed 68 °C – well below its maximal operation junction temperature of 100 °C. This once again demonstrates the capacity of the liquid cooling solution.