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

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  • 04/19/15--17:00: JIVE VLBI School 1995
  • © JIVE

    Twenty years ago, a number of enthousiastic students (including the submitter) received an invitation to participate the JIVE VLBI School, signed by the co-chairs of the organizing committee Hardip Sanghera and Leonid Gurvits. The Joint Institute for VLBI in Europe had just been established the year before, formally as a Dutch foundation, with the goal to build and operate a powerful hardware correlator for the European VLBI Network (EVN). We were all looking forward to a bright future for JIVE and the EVN.

    Today, about 100 participants gather in the Van der Hulst Auditorium in Dwingeloo for a 1.5 day Inaugural Symposium, followed by the inauguration of JIVE as a European Research Infrastructure Consortium.

    Several of these participants will still remember the VLBI School photo taken in 1995, with the JIVE founding director Richard Schilizzi (second from right), later JIVE director Mike Garrett (second from left), and many others who are still active in VLBI.

    Just like 20 years ago, our eyes are on JIVE and the EVN, and on the future of VLBI in the next twenty years.


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  • 04/20/15--17:00: An invitation
  • © JIVE

    Today, about 200 guests join the inauguration of JIVE as a European Research Infrastructure Consortium (ERIC) in Dwingeloo. The inauguration speakers will include Robert-Jan Smits, the Director-General of the DG Research and Innovation, who will hand over the ERIC plate, Louis Vertegaal, the Director of NWO Chemical and Exact Sciences, and Hans Schutte, the Director-General for higher education. On behalf of JIVE/EVN Dr. Patrick Charlot, Director of the Laboratoire d'Astrophysique de Bordeaux, chair of the JIVE Council, and Prof. Dr. J. Anton Zensus, Director at the Max-Planck-Institute for Radio Astronomy in Bonn will give speeches as well.

    During the ceremony, four prominent scientists will be introduced to the participants, who will briefly show their science results obtained with the EVN. They will be Dr. Anna Bartkiewicz from the Nicolaus Copernicus University in Torun, Poland, expert of spectral line VLBI applications, Dr. Dimitry Duev from JIVE, expert of satellite tracking and near-field VLBI, Dr. John McKean from Astron/RuG, who studies very distant galaxies that are gravitationally lensed by foreground objects, and Dr. Marcello Giroletti from INAF Istituto di Radioastronomia in Bologna, who is mainly interested in powerful radio jets from black holes, and the connection between their high energy gamma-ray and radio emissions.


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  • 04/21/15--17:00: What's in a name?
  • © JIVE

    The JIVE Council gathers in front of the new logo, just introduced to the crowd celebrating the inauguration of JIVE as a European Research Infrastructure Consortium. A little bit more than twenty years ago, JIVE was formed with the mission to build a powerful data processor for the European VLBI Network, and support the operations and the users of the EVN. It has certainly done an excellent job (as we were told). We are looking forward to the next twenty years as a new legal entity, an ERIC.

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  • 04/22/15--17:00: Girlsday 2015
  • © Harm-Jan Stiepel / ASTRON

    Today, the annual Girlsday will take place. ASTRON, JIVE, NOVA and CAMRAS will participate in the Girlsday, just like last year. The main purpose of this event is to immerse girls in their early teens in science and technology related professions.

    The girls will follow four workshops:

    - Chatting with Astronomers

    - Programming with Minecraft

    - Dwingeloo Telescope tour

    - Soldering

    The annual Girl's Day is part of a European initiative to promote girls to choose a career in Science and Engineering. In the Netherlands the Girl's Day initiatives are coordinated by VHTO. In the Netherlands 300 organisations and 9000 girls take part, while in the rest of Europe several hundred thousand girls visit over ten thousand locations.


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    © ASTRON

    Last week, the world's most important industrial fair, the Hannover Messe, took place, and of course ASTRON was attending. This year, one of the central themes is R&D. On 14 April, ASTRON and IBM presented an update on the DOME Microserver, as part of the Region of Smart Factories (RoSF). On the photo you see Gert Kruithof presenting the Microserver.

    ASTRON attended the Hannover Messe for the whole week. Our stand was visited very well. The ASTRON stand was part of the Holland High Tech House. Visitors of the ASTRON stand got inspired by Dutch technology!

    Dutch minster of Economic Affairs, Henk Kamp, visited the Hannover Messe. As part of his visit he visited the Holland High Tech House and the Region of Smart Factories. Minister Kamp was very interested in all the technologies that are being developed by the NWO institutes.

    Minister Kamp was accompanied by Amandus Lundqvist, figurehead of Hightech Systemen en Materialen(HTSM), Marc Hendrikse (HTSM), Jasper Wesseling, director of innovation and knowledge of Economic Affairs.

    HANNOVER MESSE: Get new technology first!

    The world's leading trade fair for industrial technology is staged annually in Hannover, Germany. It ran from 13 to 17 April 2015 and feature India as its official Partner Country. The central themes this year were Industrial Automation and IT, Power Transmission and Control, Energy and Environmental Technologies, Industrial Subcontracting, Production Engineering and Services and Research & Development.


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    © Madroon Community Consultants (MCC)

    Today marks the birthday of King Willem Alexander. Over the years, the House of Orange has bestowed much gracious attention on the work of ASTRON and JIVE. The Dwingeloo telescope (1965), the WSRT (1970) and LOFAR (2010) have all been opened by successive souvereigns, and various other achievements have also enjoyed royal interest.

    Since we do not have a more specific picture (no royal visit today), we offer this evocation of the golden light over the Dwingeloo heath, which could easily pass for orange.


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    © ASTRON

    In 2001 the META Group observed that increasing 'volume', 'velocity', and 'variety' of data in business was giving rise to necessary changes in data management approaches. Since then, this '3V' definition for 'Big Data' was extended with 'veracity' and 'variability'. With the Square Telescope Array (SKA) and other large-scale science infrastructures, science is also entering into the Big Data era; the SKA is posing one of the biggest data challenges ever.

    For the SKA it is clear that a substantial amount of science analysis will take place at a regional or national level. Given the size and complexity of the data at hand, regional science data centres would form a crucial supportive link between the scientists and the observed data at the telescope sites.

    The SKA is in the process of finalizing the preliminary design phase, and preparing for the detailed design phase, with a scheduled review (CDR) at the end of 2016. In this phase the role of regional science data centres needs to be further defined. Questions to be addressed include to which extend regional science data centres need to capture copies of the data, and which science communities such centres would serve.

    In this context the Shanghai Astronomical Observatory (SHAO) and ASTRON have decided to join forces to develop expertise for data centres serving our science communities. This would be aimed at SKA science, but also at other scientific fields such as VLBI, and future long wavelength radio astronomy at frequencies below the Earth's ionospheric cut-off.

    The picture shows prof Mike Garrett, director of ASTRON, signing the MOU. At his right side: prof Zhiqiang Shen, deputy director of SHAO and representing prof Xiaoyu Hong, director of SHAO. At the left and right side of the picture respectively dr Tao An, heading the SHAO-CRATIV centre, and dr ir Albert-Jan Boonstra, scientific director Dome.


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    © ASTRON

    In our efforts to improve aperture array sensitivity, we struggle with RFI to reduce its effects as much as possible. Focusing on that task, we sometimes tend to forget what has already been achieved in terms of system sensitivity and capability to detect faint astronomical signals. Our present sensitivity is such that we even should be careful not to confuse low level RFI with astronomical signals. This is illustrated with the detection of the HI-line at 1420.4 MHz with our WLNT 2x2 array of 20 cm x 20 cm.

    With the sensitivity of the present system (Tsys 35-40 K), even with its almost 60 degrees beam, we are able to detect the HI-line with a total-power measurement on the sky in the direction of the center of the Milky Way. For this measurement we use our small low-noise aperture array, in combination with a spectrum analyzer as frequency sensitive power detector. The array is placed inside THACO, lowering RFI-levels and effectively reducing the broadside beam such that it is largely filled by the center of the Milky Way. Its output spectrum shows a 1.5 dB increase in total power at the location of the HI-line, corresponding with a noise temperature peak of 55 K.

    At other frequencies, at similar power levels, RFI and intermodulation products may be seen as well (see AJDI of April 13). The measurements during a day between 10 o'clock and 17.13 hrs, showing a changing line profile (see the animated picture), confirm that we measured the HI-line.

    It is interesting to compare our "detection" of the HI-line with the original measurement by Muller in 1951 (published in Tijdschrift NERG, 17, no.1, 1952, pp. 3-15). Muller used a 7.5 m diameter Wurzburg dish, and a receiver having a system noise temperature of 7000 K. The 1.6 degree beam was directed at the galactic center of our Milky Way, integrating for 12 seconds per frequency point and a total measurement time of 20 minutes. Our system has a 35 K noise temperature, a factor of 200 (23 dB) better, with a beam that almost fully covers the galactic center. This means that the effective areas (gains) of the antennas only play a marginal role in the comparison. Instead, system noise is the dominant factor. Muller's signal was buried in the noise at almost 23 dB, while our system shows a 1.5 dB peak above the noise, in an almost instant picture (0.4 seconds per frequency point).

    As a result it is much easier to detect small signals, including low-level RFI. This illustrates the progress in receiver sensitivity since the first detection of the HI-line. The latter was a significant achievement in its own right and puts our "struggle" with RFI in a different perspective .


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  • 04/29/15--17:00: You gotta love you job!
  • © Pieter Benthem

    Being asked to join the ASTRON work-force is quite flattering.

    Being asked to shine in a professional photo shoot, surrounded by all the good that ASTRON has to offer, takes it to the next level.

    This photo shows our telegenic(*) Boudewijn Hut, acting busy with APERTIF hardware. The whole situation is carefully managed by HR & PR, in the persons of Bastiaan Spijk and Roy van der Werp.

    What can the matter be? All will be revealed soon.

    (*) The last telegenic young person that was asked to shine like this is now Managing Director of the national Space Research Organisation (SRON)


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    © ASTRON

    Friday April 10, Femke Akkermans was our guest here in Dwingeloo at ASTRON. Femke has won the National Science contest junior in 2014, and as first prize she was offered a weekend in Drenthe for four people, including a visit to ASTRON. She visited together with her father Rob, brother Joep and friend Stefanie.

    After a slice of cake and some refreshments, Roy Smits kicked off with an exclusive presentation about pulsars in the Van de Hulst Auditorium, just for Femke and her guests. Roy explained how pulsars start and what "sound" they make. In between Roy tested the guests' knowledge by asking a couple of questions.

    After the presentation, they went to the Dwingeloo telescope and had lunch at this unique location. Then Paul Boven explained about the telescope and operated it (manually) so that real live pulsars could be heard.

    As final part of the visit, Raymond van den Brink and Sjouke Kuindersma took Femke and the others on a tour around the R&D labs. Highlight was the 3D printer which was used for name tag key chains and puzzles.

    With a gift bag of ASTRON goodies including "Het Logboek" written by Anke den Duyn, the visit came to an end. Everyone was very enthusiastic and Femke and the others promised they would go to Westerbork and walk the Milky Way path that same weekend.

    As you can see in the photo collage, it was a fun visit.


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  • 05/03/15--17:00: House Preservation
  • © Hans van Someren Greve

    Regular visitors to the WSRT will recognize this house, located outside the entrance of the observatory grounds. It used to be the house of the Kommandant of the former Camp Westerbork, where jews and others were held by the Germans during WWII, prior to being transported "elsewhere".

    The house now forms part of the exhibits presented at the nearby Memorial Centre. Obviously, it is deemed important enough to be preserved in this somewhat unusual fashion.


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    © Astron

    One of the goals of low-frequency radio observations (and, therefore, of LOFAR) was to unveil low surface brightness, relic radio emission from old electrons. The relevance of this is that it allows to reconstruct the life and the age of a radio source. This is key information if we want to understand what switches on and what switches off this kind of object.

    4C 35.06 is an intriguing radio source hosted by one of the cores in the cD galaxy UGC 2489 at the heart of the galaxy cluster Abell 407. It has a complicated history of nuclear activity, reflected in its radio morphology on different spatial scales. We observe twin radio lobes surrounding the optical cores, seen in high-resolution archival VLA images (yellow contours, upper left inset, blue contours, center). A ridge of emission to the north-east of the inner lobes extends out to larger distances from the active nucleus.

    We have observed the source using LOFAR (60 MHz, LBA), with the highest resolution achieved to date at these low frequencies and have detected the steeper spectrum large-scale emission. The presence of faint radio emission at more than 200 kpc from the nucleus is now clearly seen for the first time (upper right).

    Complementary observations using the WSRT have shonw that the source has a helical morphology extending outwards, probably a remnant from past activity. Again using the WSRT, we have also observed the presence of HI at the location of the active core (the spectral profile is shown in the lower right inset). Spectral index maps highlight the distinction between the extended steep spectrum emission and the inner, more recent AGN outburst.

    The integrated radio spectral properties of such restarted sources hold clues about the activity history of the AGN. By studying objects like these which are nearby, we can calibrate our methods for studying higher redshift, unresolved radio galaxies and ascertain their life cycles as well.

    This work represents one of the chapters of the PhD thesis of Aleksandar Shulevski and is now accepted for publication in A&A. Shulevski, Morganti, Barthel et al. (including the LOFAR builders list). Preprint: http://arxiv.org/abs/1504.06642


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    © Astron

    One of the goals of low-frequency radio observations (and, therefore, of LOFAR) was to unveil low surface brightness, relic radio emission from old electrons. The relevance of this is that it allows to reconstruct the life and the age of a radio source. This is key information if we want to understand what switches on and what switches off this kind of object.

    4C 35.06 is an intriguing radio source hosted by one of the cores in the cD galaxy UGC 2489 at the heart of the galaxy cluster Abell 407. It has a complicated history of nuclear activity, reflected in its radio morphology on different spatial scales. We observe twin radio lobes surrounding the optical cores, seen in high-resolution archival VLA images (yellow contours, upper left inset, blue contours, center). A ridge of emission to the north-east of the inner lobes extends out to larger distances from the active nucleus.

    We have observed the source using LOFAR (60 MHz, LBA), with the highest resolution achieved to date at these low frequencies and have detected the steeper spectrum large-scale emission. The presence of faint radio emission at more than 200 kpc from the nucleus is now clearly seen for the first time (upper right).

    Complementary observations using the WSRT have shonw that the source has a helical morphology extending outwards, probably a remnant from past activity. Again using the WSRT, we have also observed the presence of HI at the location of the active core (the spectral profile is shown in the lower right inset). Spectral index maps highlight the distinction between the extended steep spectrum emission and the inner, more recent AGN outburst.

    The integrated radio spectral properties of such restarted sources hold clues about the activity history of the AGN. By studying objects like these which are nearby, we can calibrate our methods for studying higher redshift, unresolved radio galaxies and ascertain their life cycles as well.

    This work represents one of the chapters of the PhD thesis of Aleksandar Shulevski and is now accepted for publication in A&A. Shulevski, Morganti, Barthel et al. (including the LOFAR builders list). Preprint: http://arxiv.org/abs/1504.06642


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    © NASA/CXC/Michigan State/A.Steiner et al

    I will review the searches for black holes (BHs, both stellar and intermediate-mass) in globular clusters. Searches for intermediate-mass BHs in globular clusters have not provided convincing evidence, despite heroic efforts. Bright LMXBs in extragalactic globular clusters do provide evidence for the existence of BHs in globular clusters. Recently, new discoveries of radio-bright X-ray sources in Galactic globular clusters are providing evidence for a population of low-accretion-rate black holes with surprising properties.

    The globular cluster 47 Tucanae, which we now believe to possess an accreting black hole, is shown in X-rays in the above image. (Observation from the Chandra X-ray Observatory: lower-energy X-rays are red, medium-energy X-rays are green, highest-energy X-rays are blue.)


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    © ASTRON

    In the last week of March, a meeting was organized in Cape Town to bring together the Dutch and South African communities working on radio continuum and calibration issues connected with that. The meeting was organized as part of the activities supported by the NWO-NRF agreement (with PIs of the radio continuum group Huub Rottgering for the Dutch side and Kurt van der Heyden for South Africa, and PIs of the group on calibration techniques Jan Geralt Bij de Vaate and Oleg Smirnov). The goal was to help the two communities to expand their collaborations and exchanges of students and visitors.

    The meeting was held at the University of Cape Town and the logistics was in the hands of Kurt van der Heyden and Nicky Walker. They did a great job in taking care of all the needs of about 50 participants. The workshop has been a great success, with a full three-day program which covered a very broad range of topics, from calibration and imaging techniques, to galaxy clusters and active galactic nuclei, deep fields, magnetism and VLBI. This gave to the two communities, but in particular to the many young postDocs and PhD students, a very good overview of the many ongoing projects, including those involving new telescopes like KAT7 and LOFAR.

    The next meeting is planned to be next year in the Netherlands, but hopefully some of the new collaborations will not wait until then to deliver results and to expand further the exchange of students and visitors.


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    © ASTRON

    In the last week of March, a meeting was organized in Cape Town to bring together the Dutch and South African communities working on radio continuum and calibration issues connected with that. The meeting was organized as part of the activities supported by the NWO-NRF agreement (with PIs of the radio continuum group Huub Rottgering for the Dutch side and Kurt van der Heyden for South Africa, and PIs of the group on calibration techniques Jan Geralt Bij de Vaate and Oleg Smirnov). The goal was to help the two communities to expand their collaborations and exchanges of students and visitors.

    The meeting was held at the University of Cape Town and the logistics was in the hands of Kurt van der Heyden and Nicky Walker. They did a great job in taking care of all the needs of about 50 participants. The workshop has been a great success, with a full three-day program which covered a very broad range of topics, from calibration and imaging techniques, to galaxy clusters and active galactic nuclei, deep fields, magnetism and VLBI. This gave to the two communities, but in particular to the many young postDocs and PhD students, a very good overview of the many ongoing projects, including those involving new telescopes like KAT7 and LOFAR.

    The next meeting is planned to be next year in the Netherlands, but hopefully some of the new collaborations will not wait until then to deliver results and to expand further the exchange of students and visitors.


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    © NL SKA Office

    Extensive harmonizing and optimization discussions led to an excellent event at the second MIDPREP workshop, in conjunction with two SKA consortia meetings. The event, held in Aveiro, Portugal on 20-22 April, was felt to be optimal and timely. It was held under the aegis of the new Portuguese SKA membership, represented by the hosting Institute of Technology (http://engageska-portugal.pt/events/maad/). As at ASTRON last year, the meeting started with a MIDPREP workshop and continued with the Mid-Frequency Aperture Array Consortium (MFAA) and (this time) also with the Single Pixel Feeds SKA Dish Consortium.

    The EC-FP7 program MIDPREP facilitates the collaboration between two leading European research institutes (in Sweden and the Netherlands) and three South African university partners. It does this through the exchange of both experienced and early-stage radio scientists and engineers. In this fashion, MIDPREP supports the consortia activities on radio-optics, calibration, ICT, processing. And of course technology views and designs of MID-SKA itself, which will be sited in the Karoo.

    Excellent presentations were given (see http://www.astron.nl/midprep2015/programme.php). It was good to note that the important work on sky- and data-simulations originating from SKADS times in Oxford was carried on to S.A. by Ed Elson's work. Similarly, for the ongoing work with the EMBRACE AA Pulsar machine in Nancay by Steve Torchinsky's group. Other MFAA presentations reporting on news and progress on AA's are available in the AAMID consortium database.

    After a typical Portuguese tapas reception, the participants enjoyed wonderful Portuguese spring weather, as this picture taken at IT's entry shows. At the end of the first day, the group enjoyed a very nice cultural event where Africa and wine met the participants at the Alianca Underground Museum near Aveiro.


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    © (c) MCV, J. Morawietz

    On April 11th, the ASTRON/JIVE PV organized a percussion workshop in led by Michiel Gerringa of "Muziekcentrum Westerveld" in Dieverbrug.

    Such a percussion workshop is a nice team-building activity. Starting with no, or only rudimentary skills, you will discover new capabilities (and limitations) and you end up playing real music together with your colleagues.

    In this case, in only a few hours, we learned the basics of reading musical notation for drums, djembe playing technique, and how to play some bars of music on a mallet instrument like the marimba or vibraphone. We ended up playing a complete pop song ("The Bongo Song" from Safri Duo ) together with the award-winning Dutch percussion ensemble 'Sla je Slag'.

    It was a quite extensive and instructive but fun afternoon, with as highlight playing together with the "Sla je Slag" people on a professional stage.


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    © Arnold van Ardenne

    Old soldiers never die,

    They just fade away

    It might seem from this picture that the fading has begun, but that is of course just a trick of the light(*). Assembled here, around a beaming Richard Schilizzi, is a lively subset of the hardy pioneers that built JIVE with him, in the days that he was the first Director. The picture was taken at the recent elevation of JIVE to the lofty status of European Research Infrastructure Consortium (ERIC). Obviously this is a source of considerable pride for the Old Gang.

    From left to right: Bouke Kramer, Hans Tenkink, Jean Casse, Friso Olnon, Richard Schilizzi, Steve Parsley, Jan Buiter, Sjouke Zwier, Nico Schonewille and Martin Leeuwinga.

    (*) Even though it just happens to be Ascension Thursday today...


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    © Binil Aryal

    As you are undoubtably aware, on April 25 Nepal was struck by a strong earthquake which killed more than 8000 people and which destroyed thousands of houses across most of the country, with many entire villages completely flattened.

    Unfortunately, also the building of the Departement of Physics of the Tribhuvan University in Kathmandu, which also houses the Astrophysics Group, did not come through the earthquake unscathed (see picture). Prof. Dr. Binil Aryal, Head of the Physics Deprartment and organiser of the Kathmandu Black Holes, Jets and Outflows Conference in October 2013 (which some people from Dwingeloo attended), reports that the Institute is severely damaged and that in particular the Computation Facility of the Astrophysics Group is almost completely gone. Almost all CPUs have literally crashed, while also most other infrastructure, such as power storage, solar panels, projectors and monitors is basically gone.

    The situation in Nepal is still very bad and it will be some time before the government will able to give much support to science and science infrastructure. Therefore a number of astronomers outside Nepal (including some at Astron/Jive) are trying to organise, coordinated by Prof. Dr. Walter Saurer, the former PhD supervisor of Binil Aryal in Innsbruck, support for their Nepalese colleagues in the form of sending used laptops and other useful hardware to Nepal, as well as financial contributions. Astron and Jive have identified some used hardware that will be sent to Nepal, but if you think you can contribute something as well (hardware or money), contact Zsolt Paragi (zparagiATjive.nl) or Tom Oosterloo (oosterlooATastron.nl)


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