Are you the publisher? Claim or contact us about this channel

Embed this content in your HTML


Report adult content:

click to rate:

Account: (login)

More Channels

Channel Catalog

Channel Description:

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

older | 1 | .... | 59 | 60 | (Page 61) | 62 | 63 | .... | 71 | newer

    0 0
  • 02/13/18--16:00: Ferocious Concentration
  • © Madroon Community Consultants (MCC)

    In the drive to finish projects On Time and On Budget, a sizeable chunk of the ASTRON workforce has been locked into the Apertif Room, until the liberating phrase Habemus Apertivum is uttered. Naturally, this approach engenders fierce concentration(*) on the job in hand.

    (*) When this picture was taken, they were all staring thoughtfully into the middle distance, completely oblivious of the fact that the Dutch were (once again) cleaning up the medals in the Olympic speed skating.

    0 0

    © NASA, ESA and the Hubble Heritage - ESA/Hubble Collaboration, Acknowledgment: J. Mack (STScI) and G. Piotto (University of Padova)

    Globular clusters (in particular the densest ones) are breeding grounds for the formation of millisecond pulsars: in effect, the high rate of dynamical stellar interactions which can occur in a globular cluster core can significantly enhance the primordial population of rapidly spinning pulsars.

    On one side, this fact can give birth to peculiar binary millisecond pulsar systems, which can be exploited for various studies in fundamental physics. On another side, a large population of millisecond pulsars can constrain various properties of the globular cluster hosting them,

    After a review of some of the most notable results, the talk will discuss the new flourishing of this line of research, which will be made possible by the new instruments coming online nowadays.

    Picture: The globular cluster 47 Tucanae

    0 0
  • 02/15/18--16:00: ARTS opening strikes a Chord
  • © JvL

    Complex systems such as telescope back-ends consist of many layers of hardware, firmware, software and operation procedures. To oversee its design, implementation, and later its verification Eric Kooistra designed ARTS, the Apertif Radio Transient System, according to the "V" model. The test and integration stage from such a system has many steps, and provides a gradual improvement in capabilities.

    So when is such a system finished? From the project management and acquisition angle, this is an important question too. When is a good time to thank the team that built it, and your funding agencies?

    Late 2017, after the delivery of the servers that form the CPU/GPU-hardware part of ARTS, we decided to celebrate that particular milestone around the turn of the year, and put some elbow grease in making sure this news would get picked up and reach the tax payers that fund it. That would give us a channel to communicate about curiosity-driven research, and the progress we make in understanding our Universe; about how innovations for fundamental science are linked to economic and societal advances; and about the future, SKA.

    Thanks to Iris Nijman for press releases, Roy van der Werp and Frank Nuijens for support, Marieke Baan @ NOVA for media strategy advice and especially Poppy Savenije @ NWO for approaching her network of editors and journalists, we put a few weeks of effort into first ensuring a prime-time TV slot in a news or discussion program. The EenVandaag news program showed the most interest, and after quite some planning with their editors, the interview and camera team came out to Westerbork to film the supercomputer and the dishes. We can use their footage for our presentations or further media contacts, see

    ��[H:,Filr]EVERYONEFootage Drone over WSRT 2018 (EenVandaag)

    The resulting item was watched by 1.2 M people (26% viewer share). Two days before the item would air, our embargoed press release had been distributed to the ASTRON, NOVA and NWO press lists. Press agencies, newspapers and other media next called for background information and quotes to augment the press release text. First posts came and led to further interest, in a mild avalanche that lasted for about 2 weeks. Overall, the news was featured on all five types of media illustrated above: TV (EenVandaag and RTV Drenthe), Radio (Radio 1 Journaal, Drente Nu @ 06m28, BNR -- With shout-out to Johan Hamaker, Jan Noordam and John O'Sullivan @ 10m00s, Radio 1 EenVandaag), Printed media (De Telegraaf, Dagblad van het Noorden, Nederlands Dagblad), Social media (EenVandaag, RTV Drenthe, Netherlands embassy in the US), and Online (Tweakers, my favorite item, see the 200-post discussion below it!,,, Engineersonline, EOS Wetenschap).

    On this occasion I want to thank the team that made this GPU cluster possible, through its design (Erik Kooistra, Jan-Pieter de Reijer, Alessio Sclocco, Jisk Attema, Roy Smits, Yogesh Maan, Alwin Zanting, Alexander van Amesfoort, John Romein, Sieds Damstra, Teun Grit, Raymond van den Brink), tendering (Henk Jonkers, Gerda Sikken, Daniel van der Schuur, Janneke Wubs) and installation (Mike Sipior, Klaas Stuurwold, Leon Oostrum, Peter Gruppen, Lute van de Bult): we built an amazing machine.

    0 0
  • 02/18/18--16:00: Thank you, Ronald
  • © R&D

    One of the consequences of the recent changes in the R&D structure is the fact that the activities from the Technology Transfer Office moved from R&D staff to ASTRON staff. After having Ronald Halfwerk almost 20 years at the R&D department, we thought it would be good to pay some well deserved attention to his 'farewell' from the R&D department. We did so during the R&D plenary meeting of February 12th.

    R&D colleagues described Ronald in words like sympathetic, enthusiastic, diligent, a real optimist, control freak, very charming and 'say yes to no'. One of them mentioned that Ronald is probably the one who most frequently moved to another office/desk at the R&D department.

    Ronald, thank you for your cooperation and effort for the R&D department! We will miss you as our R&D colleague (but we are glad that you and your office will stay physically in our department)...

    0 0

    © JIVE

    The 2017 SKA calendar that can be found hanging in many astronomers offices has now made an appearance in the office of one of the most famous fictitious astrophysicists, Rajesh (Raj) Koothrapalli. Many will know that Raj is a character in The Big Bang Theory, an American comedy series that sees the lives of five friends play out against a scientifically accurate backdrop.

    On Friday 9th February "The Confidence Erosion" aired on Veronica, with December 2017 of the SKA calendar hanging behind Raj's desk.

    The simulations that can be seen stem from work presented in the scientific paper 'Simulated galactic methanol maser distribution to constrain Milky Way parameters' published in the Astronomy and Astrophysics journal as part of a project known as BeSSel (Bar and Spiral Spacial Legacy Survey). The study was conducted by Luis Henry Quiroga Nuñez and Huib van Langevelde and produced a catalogue of information on high mass stars in the Milky Way observed from the Northern hemisphere. The calendar image builds on this to demonstrate how many radio sources in the Southern hemisphere it will be possible to observe once the SKA is constructed.

    0 0

    © ASTRON

    The Netherlands-China Low-Frequency Explorer - NCLE, is a low-frequency radio experiment for the Chinese Chang'e 4 mission that will go in orbit around the Earth-Moon L2 point later this year. NCLE is aimed at observing the low-frequency radio sky, and is considered a pathfinder mission for a future low-frequency space-based or moon-based radio interferometer. This scaled-up version will have the detection and mapping of the 21-cm Hydrogen line emission from the Dark Ages period as the principle science objective. Low-frequency radio astronomy, i.e. below ~30 MHz, can only be done well from space due to man-made radio interference and due to disturbing influences of the Earth's ionosphere.

    After a very intense period of hard work the NCLE team at ASTRON delivered the flight hardware for the analogue amplifiers and calibration unit to ISIS in Delft for integration in the NCLE receiver. The ASTRON systems ensure proper signal reception, spectral filtering and amplification, and provides calibration signals.

    The left picture shows a computer drawing of the spacecraft with the three NCLE scientific monopole antennas pointing downwards, the solar panels, and the Chang'e 4 communication paraboloid pointing to the Moon and Earth. The right picture gives a zoomed-in view of one of the ASTRON electronic boards, the amplifier (LNA). It is somewhat more complex than initially anticipated, as it is designed to preserve linearity for the very wide observational bands in a harsh electromagnetic (EMC) environment. The middle picture shows Mark and David performing the last tests before hand-over tot ISIS.

    The NCLE receiver project is a collaboration between ASTRON, Radboud University (PI), Innovative Solutions In Space (ISIS), the Chinese NAOC-CAS, and is supported by the Netherlands Space Office (NSO) and ESA-PRODEX.

    0 0

    © Tiago Costa

    Quasars have been detected out to z > 7, indicating that black holes with masses of order a billion solar masses assembled well within Gyr from the Big Bang. Using a suite of cosmological hydrodynamic simulations, I will show that the rapid growth of the first massive black holes can be accommodated within the current Lambda-CDM paradigm of galaxy formation, as long as the first quasars grow in rare and massive dark matter haloes.

    A key ingredient of models of black hole growth is the influence of quasar energy/momentum on the surrounding medium ("AGN Feedback"). I will argue that quasar outflows are likely to be driven by the expansion of hot `energy-driven' bubbles and, in some cases, by radiation pressure

    on dust.

    Finally, I will show how radiative cooling of hot outflows can naturally lead to spatially extended, fast, multi-phase outflows, in good agreement with recent observations.

    0 0
  • 02/22/18--16:00: AJDI Awards 2017
  • © ASTRON

    This year we did not have one Image of the Year Award winner, we had three! Ilse van Bemmel (top right) and Gina Maffey (top left) were jointly awarded the prize for their contribution to commemorate the 50th anniversary of the first VLBI observation, on 17 April 1967 in Canada. The VLBI technique is now very mature, and still provides the highest spatial resolution in astronomy, thanks to the ongoing global collaboration. Ilse and Gina are committed in advocating VLBI through an intense outreach program.

    Besides the Image of the Year Award we had a special award for Jan Noordam (bottom right), the Award of Appreciation. This special award is presented to Jan for his enthusiasm to both encourage, and occasionally nag, us to submit a picture a day, wherefore he deeply deserves this award. AJDI is embedded in our profile such that without fail, Jan and his team ensure there is a daily update. Whilst most AJDI's reflect on progress and achievements, some are more personal or occasionally amusing. It is through Jan's efforts that AJDI is a continuing record of the vibrancy of all @ Dwingeloo. Well done Jan

    0 0
  • 02/25/18--16:00: Heating up Gemini LRU
  • © DESP

    To test the power supplies and the cooling of Gemini LRU (Line Replaceable Unit) a heater firmware design has been made for the FPGA (Field Programmable Gate Array). In this design all transceivers are used, almost all combinatorial logic, look-up tables (LUT), flip-flops and internal memory. Intentionally, the low power multipliers are not used, to maximize power consumption. The design is toggling at a clock rate of 400MHz. The result is a FPGA power consumption of 142Watt. In the final application the power consumption of the FPGA is expected to be less due to a lower clock rate of parts of the logic and full usage of the low power multipliers.

    The heater design is used to verify that the power supplies have sufficient capacity. The core power supply for example has to deliver 158A. A voltage drop of 43mV is measured for this 0.72V power supply, which is slightly more than expected. The efficiency in the two stage power supplies is 73% on average. Therefore, an additional 47W of power from the power supplies has to be cooled.

    As shown in the image, only liquid cooling is used to cool the Gemini LRU. No fans are necessary for cooling. Even given the high power consumption, the maximum temperature of the FPGA was 74°C (recommended maximal temperature is 100°C). The temperatures measured in the power supplies at the bottom of the PCB (Printed Circuit Board) are all below 70°C. These devices are cooled through the board.

    These measurements show that we are on the right track for a fully liquid cooled SKA-Low correlator / beamformer.

    0 0

    © J Hargreaves

    Recently four engineers (Renjie Zhu, Shaoguang Guo, Jiangying Gan and Zhijun Xu) visited Jive from Shanghai Astronomical Observatory. They are working on a two- to six-station correlator using the UniBoard hardware. The design is nearly complete but there were some problems with packet loss at the interfaces. After a week and a half of intense debugging, we observed data flowing smoothly through the 1Gb and 10Gb Ethernet interfaces.

    Testing will continue in Shanghai after the Spring Festival, assisted no doubt by a healthy stock of Stroopwafels!

    We hope that there will be continued collaboration between SHAO and Astron/Jive, for example on firmware for future beamformers and correlators.

    In spite of the rather wet winter, it was an enjoyable visit, and included trips to the WSRT and Lofar (thanks to Gijs Schoonderbeek and Willem Baan).

    0 0

    © ESA

    Last year, a team, including ASTRON, conducted a technology and mission study in the context of the SysNova ''LUnar Cubesats for Exploration (LUCE)'' challenge of ESA's General Studies Programme (GSP). In this study, the team proposed the CubeSat Low Frequency Explorer (CLE) mission concept, aiming at conducting radio astronomy below 30 MHz. In this band, Earth-base radio astronomy is extremely difficult or impossible due to the ionosphere, so observations must be done in space. This CLE radio mission and technology analysis is helping to pave the way towards deploying a larger scale distributed low frequency radio telescope in space, in the coming decades.

    The Sysnova mission scope includes a circular lunar orbit requirement of >500 km altitude, a total mass of

    The picture above shows CLE representatives from ASTRON, ISIS Innovative Solutions in Space (lead), Radboud University, TuE, TUDelft, Hyperion Technologies, and ESA at the end of the review at ESTEC.

    0 0

    © Public

    Radio galaxies and other 'radio-loud' AGN are widely thought to be the main mechanism providing the 'feedback' that prevents catastrophic cooling and hence limits the growth of the most luminous galaxies in the universe. But such models are based on very simplistic pictures of how radio-loud AGN work and it is very difficult to test even whether they are energetically viable. I will discuss ongoing efforts to understand the physical conditions in radio galaxies and to use that information to construct numerical and analytical models. Such models will be used to interpret large-area surveys being carried out now, with the best example being the LOFAR-LoTSS survey, and I'll discuss the process of deriving large-volume AGN samples from those data.

    Left image shows a numerical model of a powerful FRII radio galaxy by English et al 2016. Right image is the combined Chandra/HST/VLA view of Cygnus A.

    0 0
  • 03/01/18--16:00: AJDI Awards 2017
  • © ASTRON

    This year we did not have one Image of the Year Award winner, we had three! Ilse van Bemmel (top right) and Gina Maffey (top left) were jointly awarded the prize for their contribution to commemorate the 50th anniversary of the first VLBI observation, on 17 April 1967 in Canada. The VLBI technique is now very mature, and still provides the highest spatial resolution in astronomy, thanks to the ongoing global collaboration. Ilse and Gina are committed in advocating VLBI through an intense outreach program.

    Besides the Image of the Year Award we had a special award for Jan Noordam (bottom right), the Award of Appreciation. This special award is presented to Jan for his enthusiasm to both encourage, and occasionally nag, us to submit a picture a day, wherefore he deeply deserves this award. AJDI is embedded in our profile such that without fail, Jan and his team ensure there is a daily update. Whilst most AJDI's reflect on progress and achievements, some are more personal or occasionally amusing. It is through Jan's efforts that AJDI is a continuing record of the vibrancy of all @ Dwingeloo. Well done Jan

    0 0

    © Jorrit Siebenga (ASTRON) and Paul Boven (JIVE)

    Additive manufacturing, or just 3d printing, has become a serious addition within many production and prototyping facilities. Here at ASTRON, its immense benefits have already been explored for a few years now.

    These images show two custom-made parts, which have successfully been implemented as part of the design effort for accurate time distribution within the SKA1 telescopes. This requires the use of wavelength stabilized (DWDM) lasers, and external DWDM filters. For more information see Stewing White Rabbits.

  • The top picture shows the parts of the assembly forming a plug-in module to secure a DWDM filter. It consists of a spool housing and covering knob, to store and secure the DWDM filter and its connecting fibers. The design also includes a metal bracket fixing the fiber connectors to the front plate.

  • The bottom image shows an elegant but efficient solution to neatly secure optical DWDM filters inside a fiber splice tray. The part also offers safe guidance of the connecting fibers, ensuring that the allowed minimum bend radius is maintained.

  • The middle row of photos shows the parts inside the equipment that they have been designed for.

    And there you go, another custom-made integrated fiber-electronic-mechanic solution successfully covered by the great benefits of 3d printing.

    Inspired? In case you wonder if additive manufacturing can add something to your project, do not hesitate to visit the Mechanical Department and share your ideas!

  • 0 0

    © CC-BY-4.0 Tammo Jan Dijkema

    Anyone who has visited the Dwingeloo Telescope in the last five years knows that the venerable (semi-retired) 25m radio telescope can observe pulsars. The regular tour includes a live stream of the brightest pulsar around: B0329+54. Other pulsars can, and have been observed by observing a bit longer and folding the data. However, until now, no structural effort has been undertaken to do a survey.

    For this Dwingeloo Survey of Bright Pulsars (backronym suggestions welcome) we intend to observe as many pulsars as we can on 70 and 21 cm. A start has been made in January 2018. The results of the survey are available as Open Data, so that everyone can play with it. We have also tried to make the data easily accessible, by providing it in standard formats, such as plain numpy arrays. The data is available at

    For our observations, we use the backend that Paul Boven made, with a bandwidth of 35MHz and 468us time resolution (we may switch to a new backend or a better observing mode halfway). The data is dumped into filterbank format and processed with dspsr and sigproc.

    In parallel, a colleague at CAMRAS is performing the same kind of observations with a 20 euro RTL-SDR dongle and Windows software, also obtaining encouraging results. We intend to also include his results in the survey.

    The screenshot on the lower right shows a GUI for slewing the telescope to a desired pulsar, taken from PSRCAT. The program shows a list of observable pulsars with their relevant properties, such as the time of transit and the maximum elevation. Also, it acts as a database of pulsars that already have been observed. The GUI is a simple (open source) result of mixing astropy, astroplan, psrqpy, Matplotlib, PyQT5 and the python interface to the console of the Dwingeloo telescope. For safety reasons the 'slew to' button only works when the programme runs inside the telescope.

    Performing a survey takes many hours of observing time. Volunteers for joining the effort are welcome.

    0 0

    © JvL

    A few days ago, NWO announced the Vici grant winners. ARGO, the Apertif Radio - Gravitational wave Observatory is among the selected proposals. Today we will celebrate this occasion with cake!

    In ARGO, we will search for radio-afterglow and prompt emission accompanying gravitational-wave events. Have a look at the movie in the ASTRON press release for an impression of the science goals and method. Shown there is how the lights of the night sky have formed our view of the cosmos. Together with matter, these electromagnetic waves fill the Universe. Yet the metric of space and time are equally substantial and real - we feel their curvature as gravity. We can now even fathom our Universe through the swell of this very fabric of space-time: gravitational waves. Mergers of black holes and neutron stars whip up these waves. From recent direct gravitational-wave detections of merging black holes, we know their masses well, and the merger distance roughly; but we have basically no idea where in the sky they took place. Black hole mergers are electromagnetically dark. That great observational challenge meant the impact of these cosmic explosions remained an mystery - we had no clue in which direction to look. Yet, we now know mergers involving neutron stars do produce emission, especially in radio.

    Our overall aim in ARGO is to understand the physics governing the interior and the leviathan magnetic fields of these stars, and their spiral-in. We next want to see the powerful explosion of gravitational, electromagnetic and pressure waves collide, in the blast region. For this we aim to discover and interpret the accompanying afterglows and electromagnetic bursts. We will localise the events 100,000 times more accurately than gravitational-wave detectors can, to understand their origin through deep, targeted studies and follow-up.

    0 0

    © Colloquium

    The observed clustering (i.e. two-point correlation function) of galaxies is a powerful tool that can help us connect them to their host dark matter haloes. It can thus constrain potential evolutionary scenarios for galaxy populations and give insight into the physical processes that govern their evolution.

    In this varied talk, I will present some recent observational and theoretical developments relating to the interpretation of the galaxy two-point correlation function.

    First, I will present new results from the Spitzer Matching survey of the UltraVISTA ultra-deep Stripes (SMUVS). SMUVS provides unparalleled depth at 3.6 and 4.5um over in the COSMOS field. This, combined with the latest ultra-deep UltraVISTA data, allows precise photometric determinations of redshift and stellar mass. From this unique dataset, we connect galaxies selected by stellar mass to their host haloes from z~1.5-5. To interpret the observed galaxy clustering we use a phenomenological halo model combined with a novel method to account for uncertainties arising from the use of photometric redshifts. We infer that the halo mass at which the ratio of stellar mass to halo mass is maximized is 10^12.5 Msol at z~2.5, representing the first time this peak mass has been identified using clustering measurements at z>2.

    In the second half of the talk, I will discuss the clustering of bright galaxies selected at far-infrared wavelengths and will show that confusion noise in the imaging of single-dish telescopes used for surveys at these wavelengths can significantly boost the observed clustering of detected sources compared to that of the underlying galaxies (see figure). This recently discovered `blending bias' can lead to the inferred halo masses of these objects being overestimated by up to an order of magnitude. I will discuss ways in which this effect can be mitigated.

    0 0

    © Peter Maat (ASTRON) & Mark van Helvoort (Philips)

    The MRI, microphone array and radio telescope systems of Philips Healthcare, Sorama and ASTRON all work with distributed sensors in combination with a central signal processor. Although the scale of the systems is different, the approach in the technology development of their receiver systems is equal. In the DISPERSE project (, which is funded via PENTA (, Philips, Sorama, ASTRON and nine other companies/institutes collaborate on improving the performance of the three systems via e.g. the application of novel photonic/electronic technology.

    A first major event in DISPERSE was the first year review on March 2, by reviewers of PENTA. For the PENTA organization this was a special event as well since this review was the first project review in the PENTA framework. For celebrating this special occasion the PENTA director Peter Connock and the PENTA Programme Manager Sheherazade Azizi were also present at the meeting.

    The PENTA reviewers were very satisfied about the progress in our DISPERSE project and even the term "stellar" was coined (see also: and Twitter: @AENEAS_EU).

    0 0

    © ASTRON Mechanical Group

    Some time ago a multi-pad cooling solution for the Xilinx FPGA (Field Programmable Gate Array) for the Gemini LRU board for the SKA-LOW correlator was designed by Hiddo Hanenburg.

    While Hiddo is enjoying his retirement, I had to take over his role and create a follow-up design. What you see in the picture is a mono-cool block design resting on the Gemini LRU board which has to cool all the major components and the substantial part of the PCB. The mono-block design started at the end of January and now (the end of February) it has already been 1.5 weeks in production at ASTRON's Research Instrument-Workshop, in the good hands of Sjouke Kuindersma.

    As mono & cool as the screenshot seems, the more exciting it is for me because it is my very first cool-baby. First time right, right? :)), first bigger aluminum milled part (oh well, I do not count the RFoF in-house production tool . because it was only a tool, and it was tiny, this is a substantially bigger babe (yay!)).

    The block will be prepared for fitting and testing, and made ready for the CDR in Manchester in March.

    High Performance Computing, here we come! Let's cool! :D

    0 0
  • 03/12/18--17:00: Close-up of the Moon
  • © Rik ter Horst

    On the cold and windy evening of the 24th of February I had the chance to make some test-images with the 40 cm F/13 I recently finished (well, almost). Luckily, the seeing was quite reasonable so I took advantage to make some high-resolution images of the Moon.

    This image shows the area of the craters Clavius (below) and Tycho (on top). Using 'Lucky Imaging' techniques, the resolution of this image comes very close to the theoretical limits for a 40 cm telescope. The smallest details visible are well under one kilometer (around 600 meters).

    The telescope's primary mirror is a 18 mm thin-meniscus mirror, and because it's so thin it cools down very fast, reducing the internal air currents WITHIN the telescope considerably. This was the main reason to start making a thin-meniscus mirror, despite all the challenge involved in grinding and polishing such a thin mirror.

    For full resolution, please click on the image.

older | 1 | .... | 59 | 60 | (Page 61) | 62 | 63 | .... | 71 | newer