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

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    © Ger de Bruyn

    It is now a yearly tradition for 8-10 students from the University College Utrecht to visit the radio telescopes in Westerbork and Exloo. They are guided by Dr. Filipe Freire who is teaching them a course on astronomy and cosmology.

    This year, their visit came just in time (Tuesday 9 April 1600), only hours before the rain started falling. On the one hand, the rain was welcome after a month of drought. On the other hand, it made the SuperTerp soggy again.

    Besides the telescope they also got to see some of the birdlife and even a deer passing by.


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    © Copyright: ASTRON / IBM / SKA-South Africa

    DOME is the research project in which ASTRON and IBM have joined forces to create new technology for handling the huge amounts of data that will be generated by the Square Kilometre Array (SKA). The project has been up and running for about a year now. On March 19-21, ASTRON hosted the third DOME face-to-face meeting. The picture shows 30 representatives from the DOME teams at ASTRON, IBM-NL, IBM-ZRL (Zurich Research Laboratories) and SKA-South Africa.

    Progress: Team members were able to report good progress on many topics, such as:

  • retrospective analysis of LOFAR and extrapolation towards SKA;

  • data access patterns observed in LOFAR storage systems;

  • development of micro-server prototype;

  • testing of micro-pod optical data connector.

    Brainstorm: DOME research is spread across seven specific topics or work streams. One of those, compressive sampling, has recently been set in motion and was the subject of a productive brainstorm during our meeting. The main question for this work stream is: can we compact SKA's huge data rates (and therefore its processing requirements) by using clever algorithms, based on particular signal structures?

    SKA proposal: Just a week before our meeting, the SKA office issued its Request for Proposals (RfP). The RfP specifies the design work required for the SKA preconstruction phase. During the next few weeks, we will be assessing the current SKA baseline design. Our approach will be similar to the one we took on our retrospective analysis of LOFAR. The deadline for submitting our SKA proposal is June 10th. We will keep you posted.


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    © Annette de Boer

    On Friday 19 April, Annette de Boer, coordinator for education and diversity at ASTRON during 2010-2012, won the award for Physics teacher of the year at the FYSICA 2013 event at the Delft University of Technology. Every year, the Dutch Physics Society (NNV), organises the 'Physics teacher of the year'. According to the jury, Annette deserved the award because of her enthusiasm for physics that inspires students and co-workers, and the trips she organised to CERN and La Palma. She was quite overwhelmed by the positive remarks of the jury! Annette received a certificate, a money prize for herself and one for the school.

    The annual FYSICA event, this year carrying the theme 'Physics in the Year 2050', attracted teachers, industrial physicists, students and academics in physics. One of the highlights was also the lecture of Nobelprize winner Serge Haroche on individual quantum systems.


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    © ASTRON, 2013

    Over the last couple of years, APERTIF has been demonstrating the feasibility of Phased Array Feeds using a prototype system in one of the WSRT dishes. In parallel, hardware and firmware was developed for the final APERTIF system. This final system is now approaching completion. On 18 April 2013, two entire APERTIF signal paths based on the new subsystems were integrated and successfully tested for the first time.

    The left image shows the demonstrator setup: A test-tone was inserted into the Low Noise Amplifier (LNA) that amplifies and filters the signal. Next, the signal enters the Down Conversion Unit (DCU) in which the signal is converted to baseband. The baseband signal goes through the Gaincard to the ADU board where the signal is digitized. Finally, the digitized signal is sent to the UniBoard-based digital beamformer for further processing. The right image shows the resulting power spectrum, and indeed the test-tone appears at the expected position (which obviously triggered a tremendous wave of excitement across the entire lab).

    This result is a major step in the integration of APERTIF. It demonstrates that the subsystems do not bite each other, but collaborate as a real system. Also, a new phase of system integration tests can now start to further characterize and debug the system.


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    © ASTRON & SKA

    Last week, the EVN, JIVE and SKA Board of Directors met at the SKA Office Head Quarters at Jodrell Bank. It was a very busy week concluded on Friday 19th of April with the opening of the "Prof. Steve Rawlings SKA Board Room". The meeting room was formally opened by Linda Rawlings, in her late husband's honour. Many of Steve's friends and colleagues were there, and speeches were made by Profs. John Wormersley, Philip Diamond & Paul Alexander. The plaque next to the Room's main door (see image above) pays tribute to the huge contribution Steve made to the project. It is a great pity that he is no longer here to see the great strides forward the project is now making.

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  • 04/28/13--17:00: Comet meets Galaxy
  • © astropix.nl

    On the night of April 2nd, comet C/2011 L4 (PANSTARRS) was very close to the Andromeda Galaxy (M31), a rare photo opportunity.

    On a visit to Rik ter Horst in Ewer in the north of the province of Groningen, I was able to take 30, 30 second images with my Canon 5D MkII. The camera was set to 800 ISO, a 200mm F/2.8 lens was used, and the camera was on a sky-tracking mount. The sky was quite dark and the comet was even visble to the naked eye. In binoculairs it was a beautiful sight.

    At home, dark-, bias- and flat-frames were made and the images were calibrated and stacked with ImagesPlus, and post processed in Photoshop. Due to the low position in the sky, the image lacks a bit of blue.

    A full size image with all details can be found at: http://www.astrobin.com/37881/


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    © Jacob Baars

    Hierbij een paar opnamen van het bezoek van

    Beatrix en Claus aan Westerbork. Het moet ergens

    in 1973/74 geweest zijn tijdens een priv�ezoek

    aan de provincie Drenthe.

    Ik herinner me het als een zeer aangename en

    ongedwongen ontmoeting, waarbij beide gasten een

    grote belangstelling aan de dag legden.


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    © Jacob Baars

    Hierbij een paar opnamen van het bezoek van

    Beatrix en Claus aan Westerbork. Het moet ergens

    in 1973/74 geweest zijn tijdens een priv�ezoek

    aan de provincie Drenthe.

    Ik herinner me het als een zeer aangename en

    ongedwongen ontmoeting, waarbij beide gasten een

    grote belangstelling aan de dag legden.


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  • 04/29/13--17:00: Royal Patronage
  • © Harm-Jan Stiepel

    Today marks the coronation of our new King Willem Alexander and his much-admired Queen Maxima. The sister institutes ASTRON and JIVE feel particularly favoured by the House of Orange, having enjoyed many a royal visit over the years. They range from the opening by Queen Juliana of the famous Dwingeloo and Westerbork telescopes in 1956 and 1970, to the opening by Queen Beatrix of our new laboratory in Dwingeloo in 1996, and the LOFAR telescope in 2010. And of course the splendorous gathering of European Monarchs to open the La Palma observatory in 1985.

    The picture shows the visit of the crown-princely couple(*) in 2001, as part of the introduction of the young bride to the "Peaks in the Polder" of her new country. The party is captured on our very own "bridge to the 21st century". Behind them is a suitably orange radio image of our Galaxy.

    In the absence of ASTRON Director Prof Harvey Butcher, the honours were done by a delighted deputy director, who can be seen on the right, busily networking with the Mayor of Dwingeloo and a possibly influential soldier. On the left, the highly placed couple are being captivated by Prof Richard Schilizzi, the founding Director of JIVE. Hovering nearby is Relus ter Beek, the Queen's Commissioner for Drenthe province, casting a beady eye at a rather pushy white-haired individual who has not been identified.

    As part of a carefully prepared program, some of our most interesting employees had been selected to give presentations: A fresh-faced role-model female ingenieur for Willem Alexander, and a philosophe with lilting accents for Maxima. They were a big success.

    We wish the Royal Couple a prosperous reign, and are keenly looking forward to the next visit. If not to anoint yet another technical marvel, then perhaps to emphasize our prodigious scientific output.

    (*) They were not the first to favour us with crown-princessly condescension. Bea and Claus visited the WSRT in 1974, just as the cream was being skimmed, and the discoveries were rolling in.


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    © CUP/IAU/JvL

    IAU Symposium 291 "Neutron Stars and Pulsars: Challenges and Opportunities after 80 years", held in Beijing 2012, featured a rich harvest of recent scientific discoveries, looking forward to the many exciting avenues for future neutron-star research. The proceedings of this symposium have now appeared, edited by Joeri van Leeuwen (ASTRON). The volume (CUP, Amazon, PDF Preprint) starts with general, lively, comprehensive introductions to three main themes that successfully communicate the excitement of current pulsar research: a general overview,probing gravitation, and magnetars. The subsequent reviews and contributions on hot topics cover: ongoing searches for pulsars, both radio and gamma-ray; neutron star formation and properties; binary pulsars; pulsar timing and tests of gravitational theories; magnetars; radio transients; radio, X-ray and gamma-ray pulse properties and emission mechanisms; and future facilities. This range of topics clearly illustrates the diverse nature and wide application of neutron-star research. No less than 5 contributions describe the latest LOFAR pulsar results: the review (Kondratiev), the pilot search (Coenen), the low-frequency pulses (Kondratiev), the real-time pulse search (Falcke), and the B0943+10 XMM/LOFAR synchronous switching (Van Leeuwen) . Through a combination of introductory reviews and practically complete coverage of current results from across the electromagnetic spectrum, IAU S291 is a great reference for neutron-star researchers while providing an excellent read for advanced undergraduate and starting graduate students.

    The cover figure combines the 1932 detection of the neutron with the state of modern neutron-star and pulsar research, in 2012. In the left-hand side photograph, neutrons have collided with the atoms in a layer of paraffin wax, ejecting a proton. The proton path is visible in the ionization chamber. The right-hand panel shows an HST/Chandra false-color image of supernova remnant 1E 0102-7219. Overlaid for illustration is Westerbork radio data of the Crab pulsar.


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    © JEN

    Last week (25 april), the ASTRON/JIVE personnel club (PV) organized another karting event, this time on the outdoor track in Pottendijk, near Emmen. In the end, Roelof Boesenkool prevailed over the other two experienced drivers, Marco Drost and Merijn Martens. But 10 ambitious amateurs were not too far behind, and a great time was had by all.

    The participants were distributed over gender (12-1), over age (a range of 40 years) and over weight (a range of 40 kg). Most of these parameters did not turn out to be strong predictors of performance. The final result would only have been significantly different if the scores had been corrected for weight (which would have been entirely reasonable, IMHO).

    Actually, it is a pity that so few people participated this time. In earlier events, on the indoor track in Hoogeveen, we used to have up to 50 participants, who competed in teams of four. There would even be cheering fans. The excitement, noise and the warm glow of adrenalin makes brothers (and sisters) out of mere colleagues. The pecking order is radically different, and people who would normally not speak to each other have profound discussions about the intermediate scores on the screens. And, last but not least, it is an opportunity for those in the far pavillions to be a little more visible. After all, Paris vaut bien une messe, and you might even enjoy it.


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    © Trinity College Dublin

    The I-LOFAR test array of four Low Band Antennas (LBAs) hooked up to two e-Callisto receivers was installed at Birr Castle Demesne on April 18 and 19, 2013. As luck (of the Irish?) would have it, the test array picked up a number of Type III radio bursts on April 22, which were associated with a very impulsive M-class flare in sunspot group NOAA 11726. These are shown in the figure above, together with X-ray data from NOAA's GOES satellite.

    Solar radio bursts come in lots of different forms, ranging from long-duration broadband Type IV storms from electrons in large post-eruption coronal loops, to highly impulsive Type III bursts from near-relativistic electrons streaming along open magnetic field lines. The latter are associated with periods of elevated solar activate, when solar flares and coronal mass ejections are being produced by the Sun.

    Unfortunately the Sun has been very quiet in recent times, so you can imagine how happy we were when only three days after installing the Birr test array, a solar flare occurred. And what's more, a nice clear set of slightly polarised Type III bursts were picked up by the array - proof that the array is working and that Birr Castle is a great site for an International LOFAR Station!


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    © Oranje Bevrijdings Comit�ekela

    One day after the coronation of our new King, Willem Alexander of the House of Orange, one of the antennas of the giant LOFAR radio telescope received a special message from a young girl from a small village in the northern part of the Netherlands.

    On April 30th at 19:00, a balloon with a hand-written card attached to it was released in the village of Nieuwe Pekela. High up in the air it travelled south, accompanied by lots of other balloons.

    After a few hours, the balloon started its descent. Slowly it approached the crowded center of LOFAR, close to the village of Exloo in Drenthe, the Netherlands. On the 1st of May, one of the thousands of radio antennas snared the balloon, waiting for it to be found by an engineer.

    http://www.obcp.nl/nieuws.htm


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    © ASTRON/UvA

    Given the importance of training future astronomers in both the science and techniques involved in radio astronomy, three ASTRON staff astronomers (Hessels, van Leeuwen and Wise) are teaching the Masters course "Radio Astronomy" at the University of Amsterdam this year.

    The intensive course (worth 6 EC) started a few weeks ago and runs through April and May. The 12 lectures first describe the various science topics in which progress is made through radio. The various emission, absorption and propagation processes are treated -- as these can be quite different from those encountered at infrared, optical and higher frequencies. The full range of astronomical objects producing observable radio emission are next discussed: the Sun, planets, exoplanets and SETI; stars and pulsars; HI clouds, HII regions, supernova remnants; neutral hydrogen and spiral galaxies; active galactic nuclei, radio galaxies, quasars; and the CMB.

    In the labs, the students are currently each writing an observing proposal for a topic and radio telescope of choice -- potentially resulting in actual telescope time (e.g., this paper in MNRAS was the result from a similar course by JvL at UBC). After a series of hands-on labs on LOFAR, Parkes and WSRT data, including "cookbook" imaging of LOFAR MSSS data on CEP1, and solving pulsar timing solutions for a relativistic binary, the students finalize their proposals with a full Technical Justification. They next present their project, and are graded. A written exam completes the final mark.

    On May 2 this class of about a dozen young astronomers will visit WSRT and LOFAR; hopefully on their way toward becoming our future radio telescope users.


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  • 05/07/13--17:00: Orange webs
  • © Ger de Bruyn

    The WSRT, an East-West array, requires 12 hours to fill the uv-plane, using Earth rotation Synthesis, and make high qulity images. That is of course great if you want sensitivity as well. However, if you want to image a large field of view you have to resort to a technique called mozaicing, where the telescope scans a large number of positions in a short time. This produces nice (raw) images as shown above, where 2 out of 32 pointings are shown. The bright source is 3C295, about 65 Jy. The frequency is 324 MHz (but all frequencies from 310-381 MHz are recorded).

    Each of the 32 grid positions, 1.3 degrees apart in RA and Dec, was visited for only 70 seconds with 10s to move on. The total area thus imaged is about 8 x 8 degrees. By combining up to 6 12 hour observations, where the starttimes are appropriately phased to yield a slghtly rotated 'spiderweb' this will produce a full uv-coverage.

    The data will be used by the LOFAR EoR group to study diffuse Galactic foreground polarization towards 'EoR windows'. Similar data have been acquired on the fields surrounding 3C196, Elais-N1 and the NCP. Especially the latter mozaic required some creative scheduling by Hans van Someren Greve, due to limitations in the hour angle coverage of the WSRT. The data were taken on 27/28 April 2013 and will be reduced in NEWSTAR.


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    © Lars Venema

    METIS, the future mid-infrared instrument for the European-Extremely Large Telescope (E-ELT), has to observe the IR radiation from celestial objects through a "hot" atmosphere via a "hot" telescope. In order to prevent further heat contributio, the instrument (and detectors) itself will be cooled to 30-80K (10-40K). For obtaining images with good contrast, METIS relies critically on its capability to subtract the highly variable (thermal) background from the image to a high level of accuracy.

    The Cold Chopper is one of the components to make that possible. It allows the instrument to look at a source, and then quickly at a location close to the science object to measure the background. The efficiency of the observation depends on the time the system is locked (very stable) on its designated position. The transition time between the two positions should be as short as possible.

    The chopper's stability and reproducibility is better than 1.7 micro-radians, with a maximum chop throw of 13.6 milli-radians. The transition time should be less than 5 ms!

    The hardware of a demonstrator (see photo) consists of the opto-mechanical system, cryogenic voice coils (specially designed) and a laser interferometer metrology system to measure the position of the mirror. At SRON in Groningen, the chopper is now being tested cryogenically and integrated with its control system, which should provide the required accuracy and speed. The photo shows the chopper unit itself. The mirror in the centre is a fixed reference mirror. In the animation, the 2D character of this chopper is clearly illustrated.

    The project is a collaboration between Janssen Precision Engineering B.V. in Maastricht, SRON in Groningen, the NOVA-ASTRON group, together with TNO acting as consultant. See also http://esfri.strw.leidenuniv.nl/index.php?option=com_content&view=article&id=56&Itemid=62


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  • 05/09/13--17:00: Girlsday 2013
  • © Harm-Jan Stiepel

    Last thursday (25th of April) ASTRON, JIVE and the NOVA Optical/ Infrared group at ASTRON organised the Girlsday for high school girls. Girlsday is a European initiative to make young girls enthusiastic about technology and ICT, and takes place annually on the fourth Thursday in April. On Girlsday, girls can see that working in science and technology is fun and exciting. It can also help them in their choice of profiles in high school or in their choice for further studies and a career in science and technology.

    This year, we welcomed 32 high school girls from four high schools in the North of the Netherlands. The girls learned about how antennas and other instruments for telescopes work, and how a telescope as big as Europe can be simulated. They also had the opportunity to chat with astronomers and telescope operators in other European countries such as Germany, France and South-Africa. Besides this they also had the chance to build their own radio receiver.


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    © Lars Venema

    METIS, the future mid-infrared instrument for the European-Extremely Large Telescope (E-ELT), has to observe the IR radiation from celestial objects through a "hot" atmosphere via a "hot" telescope. In order to prevent further heat contributions, the instrument (and detectors) itself will be cooled to 30-80K (10-40K). For obtaining images with good contrast, METIS relies critically on its capability to subtract the highly variable (thermal) background from the image to a high level of accuracy.

    The Cold Chopper is one of the components to make that possible. It allows the instrument to look at a source, and then quickly at a location close to the science object to measure the background. The efficiency of the observation depends on the time the system is locked (very stable) on its designated position. The transition time between the two positions should be as short as possible.

    The chopper's stability and reproducibility is better than 1.7 micro-radians, with a maximum chop throw of 13.6 milli-radians. The transition time should be less than 5 ms!

    The hardware of a demonstrator (see photo) consists of the opto-mechanical system, cryogenic voice coils (specially designed) and a laser interferometer metrology system to measure the position of the mirror. At SRON in Groningen, the chopper is now being tested cryogenically and integrated with its control system, which should provide the required accuracy and speed. The photo shows the chopper unit itself. The mirror in the centre is a fixed reference mirror. In the animation, the 2D character of this chopper is clearly illustrated.

    The project is a collaboration between Janssen Precision Engineering B.V. in Maastricht, SRON in Groningen, the NOVA-ASTRON group, together with TNO acting as consultant. See also http://esfri.strw.leidenuniv.nl/index.php?option=com_content&view=article&id=56&Itemid=62


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  • 05/10/13--17:00: Girlsday Drawings
  • © ASTRON + Girlsday-Girls 2013

    Following up on a recent daily image, today we present the wonderful artwork that the Girlsday-Girls have produced at ASTRON as part of the Girlsday 2013.

    One of the activities was live chatting (via Skype) with a professional female astronomer. All questions were allowed; from work to hobbies to even more personal details. Part of the assignment was to draw their findings onto an A3-paper. To accomplish this, the girls worked in pairs and produced some magnificent artwork as can be seen in the collage.

    As the drawings reveal, the girls were very creative and productive.

    Many thanks to all the Girlsday-Girls and the female astronomers who volunteered to answer all the girl's questions to make this event so very successful! All drawings will be send to the corresponding astronomer as a reminder of this event.

    More information about Girlsday in the Netherlands can be found at http://www.girlsday.nl


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    © JIVE/ASTRON

    This week, Zsolt Paragi (JIVE) and Joeri van Leeuwen (ASTRON) are organizing a workshop about fast detection and localization of astrophysical transient sources in the radio regime. The workshop runs for 5 days, in the Lorentz Center, Leiden, and is attended by 60 participants, selected after a initial oversubscription of about ~3.

    New generation wide-field instruments, especially SKA pathfinders in the radio regime, will detect a huge number of transient sources that can be followed-up by very long baseline interferometry (VLBI) at the highest possible angular resolution. Finding and localization of these, as well as discussing the science case and realization of high resolution observations in multi-wavelength transient projects, is the main focus of the workshop. A scientific program of excellent speakers will cover Galactic neutron stars (pulsars) and black holes, gamma-ray binaries, unidentified TeV sources, novae, supernovae, GRB, tidal disruption events and astrophysical sources of gravitational waves. The instruments and techniques to be introduced are the European VLBI Network (EVN), real-time e-VLBI, WSRT Apertif, SKA pathfinders (e-Merlin/LOFAR/ASKAP/MeerkAT/MWA/LWA) as well as transient facilities and programmes in the other parts of the electromagnetic spectrum.

    The main aims of the work shop (Poster PDF) are to have both students and experienced researchers, from both the wide-field and the VLBI communities: 1) form the new collaborations needed to make this new connection of fields a success 2) learn practical hands-on methods from each other's fields in 'school' fashion.


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