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

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    © Kegel

    Editor's note: The high-tech nature of ASTRON sometimes offers special opportunities for children of employees. This is of course a particularly effective form of outreach.

    The curriculum for Dutch pre-university schools includes a thesis related to the student's future study. The subject my son selected was to check if the power of the 12 GHz signal from a geostationary ASTRA broadcast satellite is strong enough to overcome "outage" (=blocking) of the TV signal due to the Solar radiation coming from the same direction. This was tested when ASTRA was briefly in conjunction with the Sun, i.e. the satellite crossed the line-of-sight between Hoogeveen and the Sun. Information about this "eclipse" was found at http://www.satellitecalculations.com/Satellite/sunoutagestatus.php.

    From the ASTRA satellite-link budget-calculations, and the emission from the Sun at 12GHz as a "black body" radiator, it may be shown that some interference is unavoidable. The question remained whether or not it affects the quality of the television signal.

    The setup consisted of a 60cm satellite dish antenna and a satellite settopbox (thanks Albert!) tuned to the BVN channel at 12.515GHz, some RF components and a spectrum analyser borrowed from Anritsu (thanks to Patrick van der Burg!).

    When the eclipse was at its maximum on October 12th, the measurements showed indeed a rise in the noise floor, albeit not enough to block the satellite signal. The first picture shows the sunlight focused onto the front-end of the dish antenna that was pointing towards the satellite (and thus the Sun). The two spectral plots show the received signal power around 1000MHz, and the noise power around 500MHz. The top one without interference, and the bottom one with interference during the eclipse.

    The conclusion of this test is that, with a well aligned dish antenna, the power from the Sun is not strong enough to block broadcast satellite reception.


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  • 11/21/13--16:00: Visitors @ ASTRON in 2013!
  • © ASTRON

    This year, ASTRON has hosted an enormous amount of outreach activities and group visits, and the year isn't over yet! We've made a compilation of the different groups that visited the institute, ranging from primary school students to directors of regional press to ministries and this doesn't even include all the meetings, conferences, courses, individual visitors, colloquia and seminars that also took place at our facilities. ASTRON staff has seen a wide range of visitors passing through, visiting the laboratories, the control room, the newer parts of the ASTRON building such as the recently completed auditorium and the Westerbork and LOFAR telescopes.

    ASTRON highly values the visits of primary schools and high schools. Children and young adults can be inspired by astronomy and ASTRON introduces them to the fascinating world of radio astronomy and engineering. Of course we hope to encourage them to choose a technical profile in school and continue into a technological or scientific career.

    Besides this we are eager to give the tax payer insight into our activities so they can see how money is being spent. Almost every year, people can take a look behind the scenes at one of our open days, and guided tours are available at the LOFAR telescope via foundation Het Drentse Landschap. We offer many organizations and businesses the chance to visit the facilities of ASTRON.

    The photo's above show just a handful of group visits and activities:

  • The first performance of the Dutch theater company "the PeerGroup" playing "the LOFAR Expedition" at the LOFAR telescope, starring comedian Vincent Bijlo (second from the left), well-known from national television.

  • Mosaic of 4 images: The LOFAR Open Day on Saturday 5 October, organized by ASTRON and people from the Discovery Truck of the University of Groningen. ASTRON scientists gave presentations in the high-tech Discovery Truck, there were tours to the LOFAR telescope, and many children's activities: making a water rocket and shooting it into the sky, soldering together a small light or dice, and making exploded stars. The icing on the cake was a treasure hunt for kids. With a mysterious map they could find a treasure (a survival tool) hidden somewhere on the premises.

  • In the week of 7 November the annual NOVA Fall School took place at ASTRON. The group picture at ASTRON's new auditorium shows this year's group of the school, that is meant to broaden the knowledge of astronomy graduate students.

  • On 10 October, directors of the regional radio & TV stations in the Netherlands visited ASTRON for presentations and a tour of the facilities, concluded by a visit to the Westerbork Synthesis Radio Telescope. Although they were a bit overwhelmed by all the information, we hope some good articles may come of the visit!

  • On 18 October, the institute AMOLF, one of the research laboratories of the Foundation for Fundamental Research on Matter (FOM,) spent the day at the facilities of ASTRON in Dwingeloo and at the Westerbork telescope. With a full programme, the PostDocs and PhD students of this fellow NWO-institute discovered all about our scientific and technological activities.

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    © Andrew Pontzen

    The cold dark matter picture can be tested by carefully measuring the kinematics of internal motions in galaxies. Especially at the scale of faint dwarf galaxies, HI rotation curves challenge the paradigm: the density inferred is smaller than that expected. A similar problem may be arising at the scale of massive clusters containing hundreds of galaxies the size of the Milky Way. Does this mean we are seeing evidence for exotic dark matter? Before drawing conclusions one should carefully include the effect of gas and stars, which were historically seen as merely a passive component during the assembly of galaxies. We now understand that these can in fact significantly alter the dark matter component, through a coupling based on rapid gravitational potential fluctuations. I will review recent observational and theoretical developments and take a critical look at just how little we understand about the dynamics of dark matter in even the simplest scenarios. Nonetheless there is hope that future measurements can determine the nature of the dark matter particle.


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  • 11/19/13--16:00: Harm-Jan Stiepel Retires
  • © astron

    On Wednesday, November 20, 2013, one day before reaching the age of 65, Harm-Jan Stiepel retires.

    Harm-Jan is the shepherd of ASTRON's flock of sixteen Multi-Frequency Front Ends, a.k.a. MFFEs. But Harm-Jan's career dates back to well before the WSRT's MFFE-era. He started at ASTRON on January 1st, 1975, as "Ontvangertechnicus" ("Receiver Technician") at the "Stichting Radiostraling van Zon en Melkweg", as ASTRON was called in those days.

    During his 38 years at the WSRT, he has seen many changes and upgrades come and go as receiver technology progressed. While involved in MFFE development and production, Harm-Jan evolved into a true MFFE-expert, reaching well beyond electronics and into the realm of the cryogenic coolers that keep the LNAs at a frigid, noise poor 15 Kelvin. And apart from being a master troubleshooter, he is also known for his improvisation talent where and when necessary. (Note the roll of (duct?) tape on the equipment box in one of the pictures.)

    But Harm-Jan has other skills too: many people will recognise him as ASTRON's in-house photographer. He could be seen during visits of dignitaries, at open days, and many receptions, quietly walking around with his camera, recording the memorable moments of the event. Making interesting pictures comes naturally to Harm-Jan as photography is one of his hobby's.

    While searching for photo's of Harm-Jan's past for todays event, we stumbled on a picture of Harm-Jan in a posture unfamiliar to us, threatening to use a tool seen seldom at the WSRT: it is a picture made during his military service. Please note the (unlit) cigarette. We included this photo to show Harm-Jan from a very different perspective.

    As the WSRT moves from the MFFE into the APERTIF era, we say goodbye to a person from the shrinking group of people who know every nook and cranny, every bolt and wire of the current WSRT.


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    © ASTRON

    This year marks the 65th birthday of Ger de Bruyn. He has been a prominent radio astronomer in the last few decades, in particular for ASTRON, and has been instrumental in the development of LOFAR. Although Ger will continue his career thanks to the ERC Advanced Grant he just received, this special birthday could not pass unnoticed!

    To celebrate his scientific career and achievements, the University of Groningen and ASTRON organized an international conference: The Radio Universe @ Ger's wavelength� in Groningen (4-7 Nov 2013) and a one-day mini-symposium Gerfest� at ASTRON (8 Nov 2013).

    The conference had a very busy programme, focusing on the many topics that have been (and still are!) the main scientific interests of Ger: the Epoch of Reionization, the Galactic and Extragalactic Foreground Emission, AGNs, giant (and double-double) radio galaxies, variability, radio surveys, as well as radio astronomy techniques like Faraday Rotation Measure Synthesis, calibration of radio interferometers, RFI mitigation and Radio Array design in general. In other words, more than enough to fill four days with a very interesting program.

    The friday event was dedicated to the more technical part of Ger's work done in collaboration with people at ASTRON. A lot of memories went by but also a lot of plans for the future!

    Ger closed the conference and the mini-symposium by summarizing the scientific questions addressed throughout the meeting and by giving his view on the future prospects. Slides of talks are available on the conference website: http://www.astron.nl/gerfeest


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  • 11/23/13--16:00: Mercury, ISON and Spica
  • © Ramon Navarro

    In the morning of November 20th 2013 the skies cleared up over The Netherlands (at least for Dutch Standards). Finally this gave an opportunity to picture planet Mercury and comet ISON together with the star Spica.

    This image was taken from Meppel in The Netherlands in South Eastern direction at 7.52AM, which is 1 hour and 15 minutes before sunrise using a Canon 1100D with a 55mm lens. Exposure settings were 5 seconds at f/5.6 and ISO 1000. Mercury, ISON and Spica are respectively 5°, 8° and 13.5° above the horizon.

    Because ISON is only 8 degrees above the horizon it appears about 10 times dimmer than if it would have been high in the sky. This is due to the increased airmass close to the horizon. In this picture ISON is observed through airmass 7, thus observed through 7 times the amount of air relative to a star that is directly overhead (at zenith). Unfortunately the comets tail is not visible due to twilight and moonlight.

    This is one of the last times that comet ISON is visible before its approach of perihelion on November 28; the point of closest approach of the Sun. If the comet survives the intense baking of the sun it is expected to return to the night sky glorious and with a bright tail early December. By the time of the holiday season ISON will be visible the entire night. Let's hope for some spectacular fireworks!


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    © @Anne Archibald 2013

    PSR J1023+0038 is an unusual binary pulsar: in 2000-2001 it had an accretion disc, which disappeared in 2002. It is again showing signs of activity - we're still trying to understand what has happened - but in the mean time it ticked along steadily almost like a normal pulsar. We say "almost" because its radio emission did show some very unusual features.

    The left diagram shows the pulse phase (vertical) at three frequencies, for three five-hour orbits (horizontal) each. A normal pulsar would just look like smooth horizontal strips. This system shows eclipses and delays, where the signal either disappears completely or arrives late. Even though there's no accretion, there's still some plasma passing between us and the pulsar.

    The right diagram shows the system geometry. The top panel shows an edge-on view of the system. The companion is to scale and distorted into that teardrop shape by gravity and centrifugal force. Our viewing angle towards the pulsar during the full orbit varies between the dashed lines, meaning that the companion never actually blocks our view. The bottom panel shows a face-on view of the system. The wedges show the angles that are eclipsed at 1400 (blue) and 350 (red) MHz. Even though the pulsar produces a powerful wind, the plasma from the companion reaches most of the orbit.

    In Archibald et al. 2013, we try to understand what is going on. We think the companion may have a magnetic field like that of our Sun, and that the plasma flows along these field lines just like the solar wind. This would also slow the companion's rotation and make it draw closer to the pulsar, so accretion should continue. It's a mystery, though, why the accretion was so weak. Our planned multi-wavelength future observations will help answer that question.


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  • 12/01/13--16:00: Optics Galore
  • © Ramon Navarro

    Exciting times at NOVA-ASTRON these days. We are at the final stages of integration of the Cold Optical Bench for MATISSE; the mid-infrared interferometric spectrograph and imager for ESO's VLT interferometer (VLTI) at Paranal, Chile. Matisse can combine the light from all 4 eight-meter VLT telescopes.

    In this picture you can see a detail of the reimager box; one of the main modules in the Cold Optical Bench. The reimager box conditions the signals from all 4 telescopes before they are interferometrically combined. For each telescope 9 optical components are needed to condition the light (excluding slits and pinholes). In this image alone you can distinguish 20 optical components. On the right you can see the cold stops; an undersized pupil limiting unwanted thermal radiation in the system. The gold colored parts are diamond turned, powered aluminum mirrors with a gold coating. The other elements are glass optics fixtured with a mirror clip. The glass mirrors are flat or have a very long curvature radius and are also gold coated for high reflectivity in the infrared.

    In the MATISSE Cold Optics Bench the light from the telescopes is added coherently. Tolerances are extremely tight in order to achieve sufficient interferometric contrast. Despite the relatively long IR wavelengths (with respect to optical) the combined wave front error of all optical components in the reimager box is spectacular:

    MATISSE is capable of imaging at spatial resolutions of ~6 milli-arcsec in the 2.8-5 and 8-13 micrometer wavelength range. This enables the study of wavelength-dependent characteristics of gas and dust grains. This includes the formation and evolution of planetary systems, Active Galactic Nuclei and high-contrast environment of evolved stars.


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    © SKA Organisation

    On Thursday 7th November 2013 the Aperture Array Design and Construction Consortium (AADC) conducted it's kick-off. This marked the start of a three year pre-construction phase leading up to the Critical Design Review for SKA1 in 2016.

    AADC deals with the specification, design and verification of the Low Frequency Aperture Array (LFAA) component of the SKA1-low telescope. And is one of the 10 consortia working on SKA design. AADC concentrates on the antenna array, receivers and the station beam forming.

    Main partners in the consortium are: ASTRON (lead), University of Cambridge, ICRAR, INAF, University of Oxford and KLAASA (China). Further contributions are expected from Jive, GLOW and University of Malta.

    The AADC consortium will follow an "AA tradition", the all-hands in December: this year in Dwingeloo, 3-5th December. For information visit the meeting website: www.astron.nl/aadc2013.


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    © Carley et al. / Nature Publishing Group

    Cosmic rays and solar energetic particles may be accelerated to relativistic energies by shock waves in astrophysical plasmas. On the Sun, shocks and particle acceleration are often associated with the eruption of magnetized plasmoids, called coronal mass ejections (CMEs). However, the physical relationship between CMEs and shock particle acceleration is not well understood. In this talk, I will show how extreme ultraviolet, radio and white-light images can be used to study CME-induced shocks and associated phenomena such as large-scale coronal waves. I will also show how LOFAR is giving a new insight into our understanding of electron acceleration in the solar corona.

    The figure shows a solar radio burst driven by a coronal mass ejection from the Sun. The rapidly varying "herringbones" are thought to result from electrons accelerated by a super-Alfven shock that is driven by a rapidly expanding coronal mass ejection. The dynamic spectra were observed by STEREO/WAVES, the Nancay Decametric Array and TCD's Rosse Observatory at Birr Castle. See Carley et al., Nature Physics, 2013 for further details.


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    © Patrice OKOUMA [[Image courtesy of Jay Pasachoff]]

    I am a cosmologist from Gabon, presently based in Cape Town (South Africa). My research interests are increasingly gravitating towards the field of HI-cosmology. From September 22 to October 8, I was at ASTRON, working with Maaijke Mevius on how to extract ionospheric information from radio interferometric data. Our collaboration started during the 3GC-III workshop in Feb. 10-22 in South Africa. Such exchanges are bound to mature.

    On Nov. 3, a total solar eclipse swept across Africa, with a focal point in Gabon. As head of NOMMO ASTRONOMIA (http://ama09gabon.weebly.com/), the society for astronomy and space science in Gabon, I led a team of close collaborators to:

  • organize the first week-long workshop on astronomy and space science (http://eclipse2013.weebly.com/) in Libreville, capital city of Gabon from October 28 to November 3;

  • facilitate a key workshop of the OAD, a Bureau of the IAU (http://www.astro4dev.org/activities/pan-african-eclipse/oad-workshop-french/draft-agenda/). The aim was to discuss the feasibility of a French language node of resource sharing. It was held from Nov. 4 to 5 in the headquarters of the Gabonese Space Agency;

  • facilitate two scientific expeditions. The first one led by Prof. Jay Pasachoff (USA), chair of the IAU's Working Group on Eclipses. The second one led by Prof. Zhongquan Qu, solar physicist with the Yunnan Astronomical Observatory (China) who came to test the prototype of a second generation polarimeter called FASOT.

    The week-long workshop was funded by the OAD/ICTP, with also a generous sponsorship from the Lycee International Berthe & Jean in Libreville. Following these successes, plans are under way for the first School of Astronomy and Space Science for Central Africa (SASSCA) in 2014, with the goal to set it up as a biennial school. Follow-up initiatives to both workshops will constitute milestones in integrating Afrique Francophone� into growing pan-African science and technology initiatives such as the SKA and the AVLBI, while widening the pool of future users for MeerKAT, SALT and HESS.


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    © Screenshots from Maps.app (copyright Apple Inc)

    Pick a random astronomer, and they're likely to be carrying a Mac laptop. With the newly released upgrade (called Mavericks) to the operating system, there is now a map-browsing application built in. Of course the first thing a LOFAR aficionado might do is zoom in to the Exloo area! As in bing, the core area looks great. Now you don't have to remember how to get there in your web browser ...

    Also check out WSRT, where you can easily tell which of the antennas has been used for the Digestif system.


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    © ALMA (ESO/NAOJ/NRAO), APEX (MPIfR/ESO/OSO), J. Hodge et al., A. Weiss et al., NASA Spitzer Science Center

    Ever since their discovery, submillimetre galaxies (SMGs) have been regarded as some of the most fascinating, but also controversial objects in the early Universe. Their potentially fundamental role in cosmic evolution - as prominent contributors to the global stellar mass growth - has been widely debated while a number of important aspects of their nature remained speculative. The lack of high-resolution imaging of large samples of SMGs at their discovery wavelength made multi-wavelength associations difficult, generally unreliable and often even impossible, with unpredictable consequences to the inferred number statistics and redshift distribution of this galaxy population. Already in Cycle 0 ALMA's capabilities paved the way for a detailed 870um (band 7) continuum view of the flux-limited sample of 126 SMGs in the Extended Chandra Deep Field South. I will discuss how only 10 hours of ALMA integration time boost our understanding of SMGs with respect to their source number counts and counterpart association but also to (serendipitously) reveal starbursts and insights into cooling processes in the interstellar medium in the very early Universe. During this talk, I will also briefly refer to ongoing and upcoming efforts in ALMA's Cycle 1 to investigate the SMG population, particularly its most distant constituents at redshifts of z>4.

    This image shows a selection of the galaxies as seen in the sharp new observations by ALMA (in red). The ALMA observations, at submillimetre wavelengths, are overlaid on an infrared view of the region as seen by the IRAC camera on the Spitzer Space Telescope (coloured blue).


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    © JvL

    In ERC Consolidator project ALERT, we will survey the radio sky to catch extreme astrophysical explosions. Up to recently our view of that radio sky was largely static, based on a Universe that is unvarying on million-year timescales. But if you take build a high speed radio camera with frames every millisecond, as illustrated in the figure, then you suddenly find flashes of bright, brief radio emission.

    These snapshots are monochromatic but if one takes that bright pixel and looks at its behaviour of color versus time, an important effect shows up: dispersion. At lower observed frequencies, the radio waves traverse the medium more slowly, and arrive later. This slope immediately indicates how many electrons the burst encountered.

    Some bursts travel through less than the maximum electron depth expected in our Galaxy, and are thus produced a few kpc away. These bright bursts are produced by intermittent pulsars, sometimes just one pulse every hour.

    But some other bursts encountered 30 times more electrons than expected from our Milky Way. That suggests a distance of over 2 Gpc. Several of these extragalactic, or "Lorimer" bursts are now known. They must be extremely luminous. Their nature is a complete mystery.

    By finding both kinds of fast radio transient sources, using Apertif and LOFAR, ALERT aims to determine what powers these populations of extragalactic bursts and intermittent pulsars.


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  • 12/08/13--16:00: Sliding Optics
  • © Ramon Navarro

    Exciting times at NOVA-ASTRON these days. We are at the final stages of integration of the Cold Optical Bench for MATISSE; the mid-infrared interferometric spectrograph and imager for ESO's VLT interferometer (VLTI) at Paranal, Chile. Matisse can combine the light from all 4 eight-meter VLT telescopes.

    In this picture you can see a detail of the photometric slider. This component either sends all the light towards the interferometric channel or splits of part of the light of each telescope for photometric detection. The first mode is for maximum sensitivity and uses gold coated mirrors (seen grey seen from behind in this picture). The second mode is for maximum accuracy and uses Zink-Selenide with a beam splitter coating on the entrance side and an anti-reflection coating on the exit side. The Zink Selenide must be relatively thick in order to spatially remove unwanted double reflections.

    Alignment must be maintained while switching between modes and therefore the aluminum mounting surface for the optical components is lapped to optical tolerances (the shiny silver surface at the bottom of the image). This surface is also used for the bearings in order to minimize the tolerance train. On top of all optical components you see spring systems that keep the optics aligned under all circumstances; the operating temperature is 38 Kelvin and the VLTI is located in an earth quake zone.

    MATISSE is capable of imaging at spatial resolutions of ~6 milli-arcsec in the 2.8-5 and 8-13 micrometer wavelength range. This enables the study of wavelength-dependent characteristics of gas and dust grains. This includes the formation and evolution of planetary systems, Active Galactic Nuclei and high-contrast environment of evolved stars.


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    © Tom Muxlow, e-MERLIN

    e-MERGE is an ambitious Legacy survey to exploit e-MERLIN's unique combination of sensitivity and spatial resolution to study the formation and evolution of star-forming galaxies and AGN out to redshifts of z > 5. These observations will provide a powerful, obscuration-independent tool for measuring the massive star formation and AGN activity in high-redshift galaxies, hence tracing the development of the stellar populations and the black hole growth in the first massive galaxies. With a resolution of 50-200 mas in C- and L-Bands, corresponding to 1, e-MERLIN gives us our first truly reliable view of the distribution of star-formation within typical galaxies at the epoch where the bulk of the stars in the present-day Universe were being formed.

    e-MERGE will disentangle the relative contributions of AGN and star-formation, an essential step given the apparently simultaneous growth of the black holes and stellar populations in galaxies. e-MERGE will also statistically characterize the nature of the sub-uJy radio population which are the target objects for the SKA.

    I will also be presenting updated reworking and imaging from the original MERLIN+VLA L-Band study of HDF-N, together with results from recent e-MERLIN commissioning observations for e-MERGE which have been used for both initial e-MERGE science and to verify the observational parameter space of the instrument.


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    © ASTRON, 2013.

    APERTIF with the new UniBoard beam former detected its first pulsar. And even better, this is the first-ever pulsar detection with a UniBoard backend!!!

    APERTIF has been operating a PAF prototype in a WSRT dish since 2007. First, the former LOFAR-ITS data-recording backend with a bandwidth of 40 MHz was used. In 2010 a LOFAR RSP-based real-time beamformer was installed. This system demonstrated a dual-beam pulsar observation over a limited frequency band. Recently, all the prototyping hardware has been replaced with (nearly) final APERTIF hardware, which includes the new LNA, down conversion unit (DCU), AD unit (ADU) and a UniBoard beamformer. The entire system is running at the required 300 MHz bandwidth. The above plots were generated by observing the pulsar (B0329+54) for 1 hour in two ~10 MHz bands at the two extremes of the 300 MHz frequency band simultaneously. In both frequency bands the pulsar is successfully detected.


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    © Bassa/Stappers

    Pulsar J1023+0038 is a special case. First detected in 2001 as a low-mass X-ray binary in an active phase, the source switched to an X-ray quiet state shortly after that and was detected as a bright radio millisecond pulsar in 2007; it was received as the "missing link" object in pulsar evolutionary scenarios (Archibald et al. 2009; Archibald PhD Thesis 2013).

    The plot shows the monitoring of the radio pulsar since 2009 by the WSRT and the Lovell telescope at Jodrell Bank, UK. The horizontal axis shows time, with a zoom-in of 2013 at the right, and the phase of the 4.75-h orbit is shown on the vertical axis. The size of the circles correspond to the signal-to-noise of the observation (black: 1.4GHz WSRT and Lovell; red: 0.35GHz WSRT). The horizontal lines show the part of the orbit where the pulsar is normally eclipsed by its binary companion and surrounding material (a larger range is affected at lower radio frequencies).

    At the end of June 2013 (vertical dashed lines) we realized something interesting was happening with the source again, as it was suddenly not detected anymore at radio frequencies. An intense monitoring campaign followed, with additional frequencies observed at GBT (blue; 2GHz) and Arecibo (green; 4.5GHz). However, no pulsations have been detected in any of our efforts since June 15th, 2013 (Stappers et al. 2013).

    Concurrent with the radio disappearing, the gamma-rays originating from this system have shown a five-fold increase. Recent X-ray observations have shown a dramatic increase in count rates as well as rapid fluctuations on timescales of only 10 to 100 seconds (Patruno et al. 2013). Optical spectra have shown double-peaked emission lines confirming that a new accretion disk has formed around the pulsar.

    To find out what exactly is happening in this special system, we are currently following up this source with a dedicated, simultaneous, multi-wavelength campaign.

    http://arxiv.org/abs/1311.7506


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    © MSSS / ASTRON

    As you can see from the official status page, the observational part of the MSSS-HBA survey (120-160 MHz) is now almost complete. Because we are utilizing a fast and reliable pipeline for post-processing, the hardworking MSSS Team have consistently kept up with the observing schedule during 2013. This means that we can already take a sneak peek at the LOFAR sky as seen by MSSS at around 150 MHz!

    The image shown today was generated with the Aladin Sky Atlas. Using Aladin's new "HEALPix All-sky Builder" utility, it was a simple matter of providing the program with a directory full of FITS files (approximately 3000 of them!), each containing a single MSSS-HBA image created using LOFAR's awimager. For the experts, the images were not beam-corrected, and represent the median over all 8 HBA bands in the survey.

    This MSSS-HBA all-sky image is presented on a zenith projection, with a Galactic coordinate grid. The Galactic equator is the horizontal line cutting through the circle marked "Cas A" (that and the other similar grey circles mask areas surrounding the brightest sources on the sky, where the image quality is not as high as everywhere else). Along the Galactic equator several supernova remnants are visible. There are still a few blank areas where images were not yet available, but actually many of those areas have since been filled in! The HBA survey is expected to be complete by the end of 2013.

    If you haven't clicked to view the image at full resolution, you really should - the relatively small preview might hide some of the details. Even then, it should be noted that the full-resolution image shown here is still strongly undersampled. To view the whole image at its true full pixel resolution, you probably would need a screen that is approximately 50 times larger -- in both width and height!


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    © BoDwin

    Old traditions die hard. On 2 December 2013, one of them has been revived. Back in 1998, the directors of the Max Planck Institute for Radio Astronomy andJIVE, Anton Zensus and Richard Schilizzi, agreed to hold regular "neighbourhood" joint science colloquia on VLBI-related topics. The goal of these BoDwin events was to build closer ties between the Bonn and Dwingeloo astronomer groups in thefield of VLBI science. Seven of these meetings were held in the period 1998-2007 in either Bonn or Dwingeloo. For not so clear reasons (but strangely overlapping in time with the global economic crisis of 2007-2009), these meetings stopped for a few years. The great atmosphere of these events and, especially, the ever exciting football matches have been very well remembered by many of us. After some nostalgic thoughts, we have decided to give the BoDwin meetings tradition a second chance of life.

    This year a joint team of ASTRON and JIVE VLBI enthusiasts enjoyed the hospitality of the MPIfR staff in Bonn. The closeness of ties between the several institutes based in Bonn and Dwingeloo have been demonstrated by the fact that since the last meeting, some of our staff have actually changed sides! There were 24 excellent presentations (12 from each geographical side), a lovely lunch and dinner. Something was missing though: the football match. Alright, the next time we meet in Dwingeloo, there will be one. Let's stat training!


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