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A daily view of all the goings-on at ASTRON and JIVE.

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  • 09/24/18--17:00: SWENED Collaboration
  • © ASTRON

    SWENED is a network organisation in which Dutch organisations active in the field of Space Weather are united. Aim of SWENED is to exchange information and building knowledge regarding space weather, to discuss possible projects, opportunities. and innovation. The partners in SWENED also intend to cooperate where possible with the partners involved and to stimulate the cooperation with foreign space weather centers and other international networks. On September 19th at the 3rd SWENED meeting, hosted by the KNMI, a Memorandum of Understanding has been signed to emphasize the relevance of such a network organisation. This signing took place behind not-just-a-desk; it used to be the desk of Christophorus Buys Ballot. Buys Ballot founded the KNMI in 1854 with the aim to provide weather forecasts and warnings on a scientific basis. Nowadays, attention is paid to space weather as well.

    For information: the partners in SWENED are

    - KNMI

    - ASTRON

    - Joint Meteorological Group

    - Netherlands Space Office

    - TU Delft

    - CWI

    - NLR

    - S&T BV

    - TriOpSys BV

    - Fugro-Intersite BV

    - Agentschap Telecom

    - Kadaster

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  • 09/25/18--17:00: Beamforming video
  • © Bruno van Wayenburg

    Beamforming is used to develop wide-field radio cameras like Apertif, inaugurated last week in the Netherlands. This technique will also be used to "point" at objects in the sky using the SKA's fixed low-frequency antennas in Australia.

    Wondering how it works? This handy animation, that we developed in collaboration with Bruno van Wayenburg, explains the process in just two minutes:

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    © Cees Bassa

    Last July, the longest total lunar eclipse of the 21st century was visible from Europe. This total lunar eclipse occurred near Moonrise and hence near Sunset. As the fully eclipsed Moon rose it exited the Earth's shadow, which gave a great display of the change in sky color from twilight, to a starry night sky, to one completely washed out by the full Moon.

    This sequence of images shows the rising Moon pass behind the Dwingeloo telescope at 10 minute intervals, revealing the drastic change in the color of the sky.

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    © JIVE

    The e-VLBI session of 18/19 September 2018 was an important milestone. For the very first time e-MERLIN, participating with three outstations, and the 64-m Sardinia Radio Telescope (SRT, Sr), joined forces with the e-EVN in a successful e-VLBI science observation.

    The inclusion of the SRT not only increases UV coverage, but also adds a tremendous amount of collecting area to the e-EVN. e-MERLIN, an array of seven radio telescopes located in the UK with baselines ranging between 10 and 217 km, perfectly complements the longer baselines of the e-EVN. The combination of the arrays substantially increases their sensitivity to emission on a wide range of scales and will open up new science cases.

    Besides the Mark II station at Jodrell Bank (Jb), which is also a regular EVN station, the e-MERLIN outstations at Cambridge (Cm), Knockin (Kn), and Defford (De) participated in this e-VLBI session. The other participating stations were Medicina (Mc), Effelsberg (Ef), Hartebeesthoek (Hh), Onsala (O8), Tianma (T6), Torun (Tr) and Westerbork (Wb). All stations were correlated in real time using the EVN Software Correlator at JIVE (SFXC).

    The figure shows fringes between Medicina (Mc) and all other stations in the e-VLBI session (12 in total), including the three e-MERLIN outstations, and the SRT. In total three experiments were observed, all at L band frequency (18 cm), totalling 26.5 hours of observing time. Many thanks, and congratulations, to the technical teams at Sardinia, Jodrell Bank and JIVE.

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    © ASTRON

    DUPLLO is the Digital Upgrade for Premier LOFAR Low-band Observing, and was recently awarded a 3.45 MEur NWO-Groot grant.

    The festive award ceremony for DUPLLO and the other NWO-Groot projects took place Friday September 28th at Science Park, Amsterdam.

    In this grainy photo (thanks Ralph Wijers) you can see NWO Voorzitter Stan Gielen handing out the certificates.

    Thanks to everyone who made the proposal possible, and is tackling the even larger challenge of implementing this major upgrade to LOFAR. DUPLLO will deliver the deepest survey ever done from 30-170 MHz, and we're excited to see the scientific discoveries it will enable.

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    The ASTERICS collaboration is pleased to announce the symposium: "The New Era of Multi-Messenger Astrophysics" to discuss recent developments in the fields of gravitational waves, astrophysical neutrinos, the highly energetic dynamic sky, and to explore new methods for multi-messenger science and related research infrastructures.

    The past few years have been pivotal for multi-messenger astrophysics, with the first detection of gravitational waves from the merging of two neutron stars, with follow-up detections at several wavelengths and the recent announcement of a high-energy neutrino event detected by IceCube coincident in direction and time with a gamma-ray flare from a blazar detected by Fermi. Gravitational Wave and Neutrino sources and their electromagnetic counterparts, together with new developments in transient astronomy, are a vibrant field where the nature of many phenomena is still unknown or debated. Furthermore, the generation of new sensitive wide-field instrumentation across the entire electromagnetic and astroparticle spectrum (SKA, CTA, KM3NeT, ELT, Athena) are set to radically change the way we perceive the Universe. In the next decade, space and ground-based detectors will jointly explore the Universe through all its messengers. Adequate e-infrastructures and algorithms are needed to manage and analyse the data. Scientists of all ages are welcome to ask questions and share knowledge.

    The conference will be held from 25 to 29 March 2019, in Groningen, The Netherlands. It is hosted by the Netherlands Institute for Radio Astronomy (ASTRON) on behalf of ASTERICS.

    ASTERICS is a Horizon 2020 EC funded project that collects knowledge and experiences from astronomy, astrophysics and particle physics and astroparticle physics and fosters synergies among existing research infrastructures and scientific communities, with the ambition of seeing them interoperate as an integrated, multi-wavelength and multi-messenger facility.

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  • 10/02/18--17:00: Astronomy at the IAC
  • © Phil Crosby (CSIRO)

    The IAC meeting is even bigger this year and a noticeable change is the focus on the industry exhibition, rather than the IAC proceedings. It looks to have become an industry focussed event - no bad thing.

    The NL stand is quite large, and pleased to notice a section devoted to radio astronomy engineering.

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    © Colloquium

    Active Galactic Nuclei (AGN) play a key role in the formation and evolution of galaxies by imparting copious amounts of energy to their surroundings. Direct evidence indicates that so-called radio mode feedback, i.e. feedback done by radio jets, is responsible for regulating star formation in the most massive galaxies over the last half of Hubble time.

    Two parameters play a key role in determining feedback efficiency: (1) the kinetic power of AGN jets, which set how much energy is available for feedback; and (2) the timescales related to their injection, which determine the efficiency with which this energy is deposited in the surrounding gas. In principle, observations of radio galaxy populations encode this information on feedback energetics and duty cycles, yet interpreting these observations is challenging due to the highly non-linear nature of the mapping between the observable and physical properties of radio jets.

    I will describe our recent work on dynamical and numerical modeling of radio galaxies, and highlight the crucial role of the environment into which the jets expand. In this context, I will briefly describe a framework for inferring the physical properties of radio jets from large-scale surveys, and implications for our understanding of the mechanisms of jet triggering and feedback. Much can be learned from carefully constructed samples; by way of example I will show how a sample of asymmetric radio galaxies from the Radio Galaxy Zoo citizen science project can be used to probe whether galaxy clustering is a good measure of jet environment. I will conclude with a brief forward look towards imminent large-scale radio surveys.

    Image Caption: Hydrodynamical simulation of a powerful radio galaxy expanding into an asymmetric environment. The right jet is expanding directly towards the cluster centre, while the left one is moving in the opposite direction. The pressure gradient gives rise to the observed source asymmetry.

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  • 10/04/18--17:00: Open Dag / Open Day
  • © ASTRON

    Kom op zaterdag 6 oktober tijdens het Weekend van de Wetenschap naar de open dag van ASTRON en JIVE en leer alles over de grootste (radio)telescopen ter wereld!

    Hoe ontvangen we signalen uit het heelal? Hoe zien de nieuwste telescopen eruit? En wat heb je nodig om die te bouwen? Bij ASTRON ontdek je het.

    Doe proefjes en experimenten die te maken hebben met het heelal. Ga op reis door de ruimte in het mobiele planetarium. Leer programmeren en maak je eigen ontplofte ster!

    Heb je vragen die je graag aan onze sterrenkundigen en ingenieurs wilt stellen? Verzamel ze, neem ze mee en stel ze tijdens de open dag. Heb je daarnaast altijd al een kijkje willen nemen in de Dwingeloo Radiotelescoop?

    Dat kan ook dit jaar weer! CAMRAS organiseert allerlei activiteiten in en rondom de radiotelescoop. Kijk voor meer informatie hierover op .

    Neem iedereen mee op 6 oktober naar Dwingeloo. Jullie zijn allemaal welkom in de wereld van de radioastronomie!

    Find out how the world's largest (radio) telescopes are built!!

    JIVE and ASTRON will be holding an open day on Saturday 6th October, during the Weekend of Science (Weekend van de Wetenschap)!!

    You can conduct your own experiments, take a journey through space in the mobile planetarium, learn computer programming and even make your own pulsar!!

    Do you have questions about astronomy? Our astronomers and engineers will be there to answer them!

    Plus, you can also have a look in the Dwingeloo Radio Telescope! CAMRAS organises all sorts of activities in and around the radio telescope. For more information, visit

    Everyone is welcome to explore the world of radio astronomy!

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    © astron

    HI absorption offers a unique tool for studying all kind of objects in the Universe. It can be probed out to much larger distances than HI emission and one can detect it even at the highest resolution offered by VLBI. We are about to take the exciting next step in the exploration of HI absorption with new radio telescopes becoming available (ASKAP, MeerKat and Apertif) and which are close to starting a range of large surveys.

    To coordinate the efforts and to exchange technical and scientific expertise in this area, ASTRON hosted a small but active workshop from 29-31 August 2018. This was the second meeting of this kind, following the very successful first one of last year which also took place at ASTRON (see the Daily Image of 27 June 2017).

    This year's meeting was in particular useful in attracting interest from a broader community, apart from the "standard" HI absorption folks. Several teams of non-radio astronomers were present and lively discussions took place on the synergy between the Apertif HI absorption survey and the surveys planned for WEAVE (the integral field spectrograph to be installed at the WHT) as well as the imaging surveys planned by the JPAS group on the new Observatorio Astrofisico de Javalambre in Spain.

    Furthermore, the workshop provided an update on the progress made in the preparations of the absorption surveys and the first interesting results coming from all pathfinders were shown!

    A variety of science talks covered all topics, from low- to high-redshift, associated absorption as well as intervening absorption, large-area low-resolution surveys but also detailed studies at high angular resolution. If you are interested, the presentations are available on the website of the meeting.

    An important aspect of this workshop was that much time was dedicated to discussion at the end of each session, as well as a special discussion focused on the prospects of the SKA. This helped to identify a number key points that will improve the collaboration between the groups. You can find reports from these plenary discussion sessions on the website mentioned above.

    A total of 33 participants from all around the world came together at ASTRON, with an almost perfect gender balance. About half the talks were given by PostDocs and PhD students. Based on the feedback from the participants, this meeting was again a success and it has been agreed to continue the good work with both IUCAA (Pune), ATNF/Sydney University and Oxford all happy to host the next editions.

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  • 10/08/18--17:00: Weave Lens Alignment Tool
  • © schuil

    Last week the WEAVE Lens Alignment Tool production finished. It is a development for mechanical aligning each of the eight lenses of the two (Red and Blue) Weave Cameras. The tool contains five CNC milled pieces and will be assembled together with an extreme (sub-micron) accurate air bearing to one unit. The tool will be used in conjunction with the measurement machine to align the lenses inside the camera housing by adjusting a small wedge/spindle mechanism to micron level.

    The pictures show integrated blade springs of a thickness of 0.5mm. Small milling tools and careful milling is required to create the different springs. Milling tools of diameter 1.5mm and 15mm depth where no exception. You can imagine that milling of the section what is carried by the blade springs is impossible due to movement and vibration. A special milling fixture overcomes this problem. Several WEAVE camera lenses are in (from INAOE, Mexico and TNO, Neth.). The camera housings are ready and soon the alignment tool will be assembled and first lenses aligned. A new post will be done when the tool is in use.

    WEAVE is a new multi-object survey spectrograph for the William Herschel Telescope (WHT), on La Palma in the Canary Islands. WEAVE is built by several institutes at several countries.

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    © Robert Schulz

    For sometime now I wanted to create a 360-degree animation that can be experienced with and without virtual reality headsets. The first results of this endeavour are now available on YouTube. There are two videos that show a LOFAR international station created entirely with Blender. Both videos are rendered in 3D and allow you to look around in 360 degree. In one video the camera moves across the station from the HBA to the LBA. Many thanks to ARTS for making this version possible by rendering it on the cluster. It took the ARTS GPU cluster only about 1h and 16min to render 2700 frames at a resolution of 2560x2560 creating about 67GBytes of image files. In the second video the camera is not moving, but this allowed me render only a single frame on my home machine at a higher resolution of 5120x5120. The Daily image shows screenshots from this video. Both videos can also be enjoyed in 2D and 360 degrees without a VR headset.

    Links to the videos: and

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  • 10/10/18--17:00: The Big Wipe
  • © ASTRON

    The LOFAR post-processing cluster "CEP4" uses the Lustre file system for its main data storage. Lustre is a distributed, shared file system, capable of massive parallel reads and writes of large data files and is used by the largest HPC clusters around the world. In terms of hardware, the CEP4 file system consists of 20 data servers and 19 disk arrays with in total 1104 spinning disks, yielding a net capacity of 3.5 PB. In July, it was decided to give it an upgrade from v2.7 to v2.10 in order to mitigate known problems in the older version.

    Since all data would be wiped in the process, some weeks of careful preparation followed. Circa 2 PB of data, worth many observing hours, was to be shuffled to the tape archives (LTA) and local hard disks by various people in the RO, while data was still being added on a daily basis. Production never stops!

    Installing a file system on such a large system can be a daunting task but this time it wasn't. All hardware was already in place and since v2.10, Lustre includes the Integrated Manager for Lustre (IML) tool. After a few clicks, sit back and let the auto-discovery and auto-configuration do the work for you.

    On the picture our colleagues Hopko Meijering and Robin Teeninga from CIT at the University of Groningen, working in IML just moments before wiping the old data. A slightly nervous moment. After the file system creation, some physical cable pulling was done to test the high availability of the various redundant components.

    CEP4 is now operational again and well equipped for a few more years of processing.

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  • 10/11/18--17:00: ASTRON/JIVE/NOVA Open Dag
  • © ASTRON

    Open Day 2018: a big success!

    On Saturday 6 October 2018, more than 500 people visited the ASTRON/JIVE/NOVA Open Day during the Science Weekend (Weekend van de Wetenschap).

    The day was filled with activities around the theme Building the world's largest (radio) telescopes: from an interactive interferometry demo showing how our radio telescopes work, a data path illustrating the increasing amounts of data we have to deal with, coding workshops, R&D and Correlator tours, to building mini-SKA dishes and pulsars with kids.

    The many activities all showcased the amazing work we do here at ASTRON, JIVE and NOVA.

    A big thank you to all the volunteers!

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    © Roy van der Werp

    Friday 12th October marked the first day of the APERTIF shakedown, an operations test designed to help us assess how the overall system is doing and how close we are to our aimed-for model of operations. For 11 days straight, there will be a mix of interferometric and ARTS observations, as well as calibrations, in an action-packed schedule. We'll be making use of both the APERTIF Task DataBase (ATDB) and the APERTIF Long Term Archive (ALTA) to manage and ingest all observations carried out. For the APERTIF imaging surveys, the goal will be to test the current reduction pipeline, assess data quality, and determine the effectiveness of survey observing and calibration strategy. For ARTS, observations will be conducted for science cases involving timing pulsars and finding new FRBs. These observations will test the system stability and sensitivity over long duration observations as well as the real-time transient search pipeline AMBER. The lead-up to this first APERTIF shakedown has been a culmination of a lot of effort and hard work by many people, only some of which are pictured in this photo. We are looking forward to a busy 11 days, as well as many lessons learned to help us improve APERTIF for the fast-approaching start of 2019!

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    © MingChuan Wei, Harbin Institute of Technology

    This image shows our own planet Earth, as well as the far side of the Moon. The image was taken with a camera linked to an amateur radio transceiver onboard the Chinese Longjiang-2 satellite, currently in orbit around the Moon, and transmitted back to Earth where it was received with the Dwingeloo telescope.

    This image represents the culmination of several observing sessions spread over the past few months where we used the Dwingeloo telescope in collaboration with the Chinese team from Harbin University of Technology, who built the radio transceiver onboard Longjiang-2, and radio amateurs spread across the globe. During these sessions we tested receiving telemetry through low-bit rate and error-resistant digitally modulated GMSK transmissions, as well as the JT4G modulation scheme designed by Nobel prize winning astrophysicist Joe Taylor for weak signal Moonbounce experiments. Besides telemetry, we performed a VLBI experiment by simultaneously observing Longjiang-2 from China and Dwingeloo, and also downloaded images taken by Longjiang-2 of the lunar surface, lens flares, and the starry sky as seen from lunar orbit.

    The transceiver onboard Longjiang-2 was designed to allow radio amateurs to downlink telemetry and relay messages through a satellite in lunar orbit, as well as command it to take and downlink images. In that it has succeeded, as many radio amateurs have received telemetry and image data. Being able to use the Dwingeloo telescope to help with this has been a lot of fun.

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    © nl-RSE

    Earlier this year, the initiative was taken to organise the Dutch Research Software Engineer (RSE) community, inspired by the British and German RSE initiative. On 20 september, the first meetup was organised in Utrecht at the Jaarbeurs Innovation Mile.

    The concept of RSE is broadly defined as any person writing software to be used in science, including but not limited to PhDs and postdocs writing software packages, software developers at universities, and independent developers working in the academic field. The goal of the meetup was bring together members of the Duth RSE community and identify what topics are important and of common interest to the Dutch RSE field.

    The full ASTRON Science Data Group (both members! Try to find them in the picture) was present at the meeting. The keynote speech was given by one of the initiators of the UK-RSE movement, Ilian Todorov. The rest of the meeting consisted of discussions about what the Dutch RSE community should focus on.

    We look forward to what this movement could achieve in improving the quality and recognition of software in the Dutch academic community. If you want to keep posted on this topic, consider joining the mailing list here.

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    © Colloquium

    Cosmic-ray bombardment initiates the production of a number of different isotopes in the atmosphere, particularly 14C (or radiocarbon). The activity of 14C in the atmosphere has varied over time due to modulation of the incident cosmic flux by heliomagnetic and geomagnetic effects, and the release of 14C-depleted carbon into the environmental by climatic effects and volcanism. The past record of 14C in the atmosphere is preserved in natural tree-ring archives. Such time-series show that year-to-year variation has usually been around 1-2%.

    In 2012, a Japanese team measuring 14C measurements on known-age tree-rings discovered a sudden jump in activity (~12�) between 774 and 775 CE. Soon after, the same pattern was found in tree-rings from Russia, Germany, US and New Zealand, proving the uplift was both global and synchronous. No known terrestrial environmental process could have caused such rapid and simultaneous enrichment. Hence it was quickly realised the cause must have been a major burst of radiation from space. Moreover, estimations of the energy of the event suggested it was too intense to be attributed to solar activity. Galactic supernovae, gamma-ray bursts, cometary impacts and solar superflares have all since been posited as the cause. A key factor in understanding the events has been the discovery of three more rapid increases in 14C activity: in 993 and 1218 CE, and 3372 BCE. This seminar will cover the ongoing debate around the astrophysical origin of these events, as well as touching on their wide-ranging implications.

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  • 10/18/18--17:00: Christiaan Huygens prijs
  • © ASTRON

    The Christiaan Huygens prijs is awarded annually for an outstanding Dutch PhD thesis. Each year the prize is granted in one of the fields of study in which Christiaan Huygens made a sizeable contribution.

    This year the prize was awarded to Adrian Hamers, who completed his thesis "Hierarchical Systems" at Leiden University. Adrian's thesis presents a generalised approach to modelling the gravitational interactions of many-body systems in which there is a hierarchy of distinct size scales. Honourable mentions were awarded to Tjalling de Haas (Utrecht) and Nienke van der Marel (Leiden).

    The jury consisted of members from the Royal Dutch Academy of Sciences (KNAW) and De Jonge Akademie: Amina Helmi (Groningen), Henny Lamers (Amsterdam) and Jason Hessels (ASTRON/Amsterdam). The ceremony took place at the Oudekerk in Voorburg, only a stone's throw away from where Huygens lived and worked.

    It was stunning to see the research talent that exists in the Netherlands, and a joy to celebrate both science and the achievements of young Dutch researchers.

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  • 10/21/18--17:00: Dr. Daniele Michilli
  • © ASTRON

    On September 14th, 2018, Daniele Michilli (ASTRON/UvA) successfully defended his PhD thesis at the Aula of the University of Amsterdam. Daniele's thesis is entitled "Discovery and characterisation of fast radio transients", and features work done with both LOFAR and the Arecibo telescope in Puerto Rico. Daniele developed a pipeline to discover several intermittently emitting radio pulsars as part of the LOFAR LOTAAS survey (one of which is pictured on his thesis cover); he performed a detailed study of pulsar B2217+47, whose pulse profile is being distorted by propagation effects in the intervening interstellar medium; and he discovered that the repeating fast radio burst source FRB 121102 is in an extreme and dynamic magneto-ionic environment.

    In addition to Promotors Jason Hessels and Michiel van der Klis, Daniele also received supervision and mentorship from ASTRON/UvA astronomers Cees Bassa, Vlad Kondratiev and Anne Archibald. He is now pursuing post-doctoral research at McGill University in Canada, working in the CHIME team of Vicky Kaspi.

    Dr. Michilli's PhD research was financed by the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Starting Grant agreement nr. 337062 ("DRAGNET"; PI: Hessels).

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