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 | .... | 4 | 5 | (Page 6) | 7 | 8 | .... | 71 | newer

    0 0

    © S. R. Kulkarni, Palomar Observatory

    That occasionally new sources ("Stella Nova") would pop up in the heavens was noted more than a thousand years ago. The earnest study of cosmic explosions began in earnest less than a hundred years ago. Over time astronomers have come to appreciate the central role of supernovae in synthesizing new elements (and making life as we know possible).

    The Palomar Transient Factory (PTF), an innovative 2-telescope system, was designed to explicitly to chart the transient sky with a particular focus on events which lie in the nova-supernova gap. PTF can find an extragalactic transient every 20 minutes and a Galactic (strong) variable every 10 minutes. The results so far: classification of 2000 supernovae, identification of an emerging class of ultra-luminous supernovae, the earliest discovery of a Ia supernovae, discovery of luminous red novae, the most comprehensive UV spectroscopy of Ia supernovae, discovery low energy budget supernovae, clarification of sub-classes of core collapse and thermo-nuclear explosions, mapping of the systematics of core collapse supernovae, identification of a trove of eclipsing binaries and the curious AM CVns.

    Image: An areal view of the Palomar Observatory (California). The discovery engine is the 48-inch telescope (extreme left) and the photometric classification is done at the 60-inch telescope (extreme right). Spectral classification is undertaken at the 200-inch telescope (center). The very first synoptic survey undertaken with a wide field Schmidt telescope was F. Zwicky's 18-inch and is the small

    dome to the right of the 200-inch.

    0 0

    © ASTRON/Nancay

    A few weeks ago, the chairman of our board, Prof. Karel Gaemers found himself on holiday, and in the vicinity of Nancay Observatory. We were able to arrange for our good friend and colleague at Nancay, Steve Torchinsky, to give Karel, his son-in-law and an old friend, a personal tour of the observatory. The images above show their tour of the facilities there - including the EMBRACE station. Karel and the other guests very much enjoyed the tour and were impressed by the breadth of research being conducted at Nancay.

    0 0

    © ASTRON

    During the holiday season, some of us sleep in tents and rely on tent pegs to hold up these light and nimble structures. It can be a frustrating experience to hammer down the pegs into a hard soil. For each situation, there is a specific type of peg to ensure a good night's sleep.

    Some of us also use such ground anchors to secure other types of structure. For instance the SKA Mid-Frequency Aperture Array (MFAA) environmental prototypes, which will be placed at the South African SKA site. Some of these prototypes are also light and large like tents, and need good anchoring to ensure their location over time.

    Two experienced camping enthusiasts where sent to the site to investigate which type of anchor is best for this case.

    The investigation was executed in two phases. First the maximum holding power of each type of anchor was tested by sheer muscle power, in combination with a spring balance. After that, an endurance test setup was assembled and placed near the PAPER array. This setup will be there for several years to see how aspects like corrosion, flooding and creep will influence the different anchoring methods.

    Both camping enthusiast concluded that the SKA South Africa soil (compact sand) is hard to penetrate with for instance a screw type of anchor. However, the pin anchor which is hammered into the soil will hold very well. Holding strengths exceeding 150 kg were measured, which allows the safe installation of the environmental prototypes in the near future.

    0 0

    © ASTRON

    In a paper we publish today in Science, the first clear evidence is presented that radio jets from the supermassive black hole in the centre of a galaxy clears gas away from the galaxy.

    Astronomers have been puzzled for quite a while by the fact that many galaxies in the Universe seem to be depleted of their gas and, as a consequence, are not able any more to form any new stars. One of the main results obtained with the WSRT in recent years is the discovery of the existence of very fast outflows of cold gas in a number of galaxies that have an active galactic nucleus, and it was suspected that these outflows play an important role in making galaxies gas poor. However, the mechanism driving these outflows was not understood because with the WSRT one can establish that outflows occur, but the resolution of the WSRT is not good enough to determine where in the galaxy the outflow occurs.

    By using global VLBI observations we have been able, in one of the galaxies where WSRT data showed a fast outflow exists, to directly map the distribution of the outflowing gas and directly witness the interaction between the plasma jet and the gas and how it is pushed out from a galaxy. Despite the strong push received from the jet, the temperature of the gas is low. But this is exactly what is needed to make theory of galaxy formation and observations to agree. Cold gas is the fundamental building block of new stars. If this gas is expelled, star formation stops. The results of this new study could not have been in better agreement with our expectations and the expectations from numerical simulations.

    The success of the observations means that VLBI is a suitable technique to study the effect of the super massive black hole on the gas in its vicinity and we hope to use this technique to study more objects where jet-driven gas outflows are suspected to exist.

    As final important note, we would like to emphasize that part of this study has been done as ASTRON/JIVE Summer Student project by Judit Fogasy (from Budapest).

    Not a bad result for a student just starting her PhD!!!!

    More can be found in Radio Jets Clearing the Way Through a Galaxy: Watching Feedback in Action, R. Morganti, J. Fogasy, Z. Paragi, T. Oosterloo, M. Orienti, Science, 6 September 2013

    0 0
  • 09/09/13--17:00: Almost 3D
  • © Rik ter Horst

    This spectacular "3D" image of the lunar surface was taken during rather good conditions in the early morning of August 27th. It is close to the terminator, so the low Sun casts impressive shadows that beautifully emphasize the rugged terrain. It makes one think of the ancient Greeks, who already suspected that the features they could see on the Moon were mountains, but could not be sure.

    The telescope was a home-made 250 mm F/15 Schmidt-Cassegrain. An ASI120MM monochrome camera (CMOS) was used to capture 3000 short-exposure (10ms) images. The 50% best ones were "stacked" with the program Autostakkert!2. This means that the selected exposures were added together after correcting them for small position shifts (and even some low-order deformations) caused by the Earth atmosphere. Some further processing (wavelets) was done with Photoshop.

    The availability of (free!) Lucky-Imaging software made it possible to achieve diffraction-limited performance without the need for expensive Adaptive Optics (AO) systems. Moreover, this was done at sea-level(!), from a location in the northern Netherlands. The smallest detail that is visible in this image is about 800m.

    0 0
  • 09/10/13--17:00: Water-skiing 2013
  • © ASTRON

    A sunny sky and a comfortable 28 degrees Celsius were the icing on the cake during the Water-ski event on September 5th, organized by the ASTRON/JIVE PV. Around 20 employees had gathered at the Ermerstrand, where a closed-course cable system tows water-skiers and wake boarders around the lake. On arrival we were treated to some inspirational wakeboard trickery by the Dutch wakeboard champion and so our goals were set: let's try to make it to the first turn.

    Water-skiing and wakeboarding are activities that require practice before you can even call yourself a beginner, because you first have to master the launch. On water-skies it is essential to carry your buttocks as low as possible and to keep your arms straight. If you manage to survive the initial jerk of the tow rope, and then remain on your skis for the first 30 or 40 meters you may call yourself a beginner.

    Only a few of the ASTRON/JIVE daredevils actually succeeded in their first attempt. The majority required several attempts to master the launch. There were many demonstrations of how NOT to do it: pulling the tow rope to the body, bending forward, getting up too early. We even witnessed a perfect "faceplant" where the tow rope was stubbornly grasped, while the water-skies were already heading for the bottom of the lake.

    After you made it through the first critical 50 meters (feeling quite euphoric) you were soon faced with the next challenge: the first turn reduces you straight back to clumsiness and panic. Again, it took most participants several attempts to master it, and then there were another three turns to negotiate. It was heart-warming to see the persistence of (most of) the participants, and in the end most of us managed to complete a lap.

    After two hours of intense water skiing and wakeboarding we called it a day. We swapped experiences over drinks, and the afternoon was concluded with a tasty barbecue and a lovely sunset. Many thanks to the PV for organizing this event. We had a great time, even though our arms will hurt for a week.

    0 0
  • 09/11/13--17:00: The class of '88
  • © -

    September 12 1988, 25 years ago, was the first day of the first European VLBI School in Castel San Pietro Terme, near Bologna. It proved an important starting point for a number of interesting astrophysical projects, collaborations and careers. But looking at the conference photo, there must have been something in the water that has "blessed"� this class also with a quality to accrete management responsibilities.

    Indeed you can make out about half of the ASTRON and JIVE management team in the picture: Mike Garrett, Leonid Gurvits, Huib van Langevelde, Raffaella Morganti and Ren� Vermeulen. Additionally a number of very well-known (European) radio astronomers can be identified in the photo too. Certainly not all the management potential emerging from this miraculous resort accumulated in Dwingeloo!

    Although the '88 event (two-weeks!) focused entirely on VLBI, it is noteworthy that its 25th anniversary coincides with the current European Radio Interferometry School (ERIS) in Dwingeloo this week. In a much more modern (i.e. condensed) programme a wide range of radio facilities are covered, including hands-on tutorials. There was no such thing in 1988; in fact AIPS could only just be used for imaging at that point.

    However, many important traditions started in Castel San Pietro, most importantly the football match, in which we lost to a local team in 1988. Looking back at this picture with some melancholy, the current management can only hope that similar friendships and collaborations are stemming from this year's school.

    0 0

    © ESO

    ESO has made a great movie about the new SPHERE instrument for the VLT, and specifically the working principle of the polarimetric planetfinder ZIMPOL.

    SPHERE is the "Planet Finder" instrument for the ESO Very Large Telescope (VLT) in Chile. It is presently in its Preliminary Acceptance Europe (PAE) phase.

    SPHERE-ZIMPOL is a high-precision imaging polarimeter, working in the visual range. It is one of the three focal instruments of SPHERE, and is developed by a consortium of ASTRON/NOVA, University of Amsterdam, ETH Zurich and University Utrecht.

    The shipment of SPHERE to Chile will take place in December 2013, followed by commissioning in 2014. For more detailed information, see

    0 0
  • 09/15/13--17:00: WSRT, spotlight on!
  • ©

    Telescope 6 presents(*) her slender frame to the 106 participants of the ERIS 2013 interferometry school, who are enjoying a magical barbecue at the famous Westerbork Synthesis Radio Telescope (WSRT).

    (*) RT6 was illuminated by 3 halogen lights of 1500W each.

    0 0

    © European VLBI Network

    Yesterday, as part of the final review of the EC-sponsored NEXPReS programme, five telescopes of the European VLBI Network, equipped with the next generation of European built VLBI digital receiver system (DBBC), succesfully demonstrated 4 Gigabits per second e-VLBI.

    This observing mode quadruples the sampled sky bandwidth and with that doubles the sensitivy of the array compared to the current maximum observing data rate of 1Gbps.

    Radio telescopes located in Metsahovi (Finland), Effelsberg (Germany), Yebes (Spain), Onsala (Sweden) and Hartebeesthoek (South-Africa) observed the source J1800+3848, a distant quasar at z=2, in the X-band experiment TE110. 512MHz of sky bandwidth was observed in both polarizations. After correcting for the clock offsets at the participating stations a strong fringe was observed, as shown in the plots.

    Using the FiLa10G card, part of the DBBC system, each 4Gbps data stream was duplicated onto its two 10GE ports. One copy of the data was recorded locally. The other copy was split into four 1Gbps streams on-the-fly. Each stream was sent off to one of four SFXC instances (running at JIVE) for immediate correlation, showcasing the possibility of distributed correlation. Due to insufficient network bandwidth (only 20Gbps of incoming bandwidth is available to JIVE), and cluster capacity, only four out of the five stations could be correlated simultaneously.

    This demonstration could not have been done without the financial support of the EC and a enormous amount of coordinated effort by a lot of individuals at the various institutes across Europe and Africa. Its succes demonstrates the strength of the international collaboration that forms the basis of the EVN. A big thank you goes out to everyone who participated.

    0 0

    © HST / ALMA / Jon Marcaide

    Supernova 1987A is the nearest supernova seen in over 400 years and the only one with an identified progenitor star. Besides the debris, a triple ring system is visible. The geometry of the inner ring has been determined and the interaction of the external debris with the inner ring has been monitored in the radio, IR, visible and X-rays. A couple of years ago, Herschel observations provided evidence of massive dust formation in the inner debris. Very recently, the new sub-millimeter array ALMA has imaged the supernova in 4 frequency bands filling the gap between radio and IR. The images have permitted to reliably dissect the SED in its components. Dust and synchrotron emissions are now well characterized. Unexpectedly, strong emission by rotational transitions of CO and SiO in the inner debris has been detected and characterized. This way, SN1987A offers a splendid occasion to study dust and molecule formation in supernova explosions. Further study of the molecular emission at higher transitions and with higher and higher angular resolution provided by the yet to be completed ALMA yields high promise for a tomography of the inner debris. All available recent results will be presented and compared to state-of-the-art VLBI studies of the expansion of SN1993J in M81.

    0 0

    © David Starkey, Maaijke Mevius, Vibor Jelic, Ger de Bruyn

    Polarized radio signals that propagate through the ionosphere are subject to Faraday rotation of the plane of polarization. For polarization studies it is important to correct the data for this (time-varying) effect. One way to estimate the effect is using a model for the earth magnetic field combined with absolute TEC models that are obtained from fits on GPS data and can be found online (eg. ). The time and spatial resolutions of these external measurements are limited. Therefore, it would be a great benefit if one could obtain the ionospheric Faraday rotation directly from polarized sources in the field of view.

    Above we see the analysis of two polarised sources in an Rotation Measure (RM) cube centred on 3C196. The upper right plot shows a 3 arc minute resolution image of a point polarised source at Faraday depth -4 rad/m^2. Upon re-examining this source at higher 6 arc second resolution it appears that it is in fact a double radio source (shown top left where the colour axis is now total intensity).

    The lower left plot shows a Gaussian fit (green dashed line) to the peak in the Faraday spectrum for this source (green solid line), and another at a Faraday depth -16 rad/m^2 (blue lines). This fit was performed on 7 RM cubes, each averaged over 1 hour of observation time. We see a hint of a double peak in the Faraday spectra of the source at Faraday depth -4. rad/m^2, a result of the two radio sources in the double having slightly different Faraday depths.

    Performing the same analysis on each subsequent hour shows a slight variation in Faraday depth caused by ionospheric Faraday rotation. In the lower right figure one can observe that these variations are in agreement with GPS predictions.

    0 0
  • 09/24/13--17:00: Flying over the Moon
  • © Rik ter Horst

    Another "amateur" image of an interesting part of the Moon, taken from sea-level on the 27th of August with a homemade 250 mm F/15 Schmidt-Cassegrain telescope and an ASI120MM camera.

    A long, long time ago (billions of years, in fact), when our Solar System was a dangerous place, one side of the Moon was flooded with oceans of molten lava. These subsequently hardened to a smooth surface, hiding all but the highest mountains. Since then, a greatly diminished meteorite bombardment has only dented the new surface with a few small craterlets.

    Staring at this wonderful image is like flying high over the Sahara desert in an aeroplane. Only the view is better, despite the vastly greater distance. The eye is constantly drawn to a miriad mysterious features that tell an ancient tale to those who know how to look.

    0 0

    © R. Pizzo

    The Fifth European Radio Interferometry School (ERIS) was hosted by Astron and JIVE in Dwingeloo, the Netherlands, between 9-13 September 2013. The event was sponsored by RadioNet, the host institutes, the DAGAL Network and the University of Groningen, as well as by the Leids Kerkhoven-Bosscha Fonds (LKBF) in the Netherlands.

    ERIS has provided a week of lectures and tutorials on how to achieve scientific results with radio interferometry. 84 regular participants attended the event, together with tutors and helpers. In total we have accommodated about 100 people. The lectures and tutorials took place in the brand new Auditorium in the new building of Astron/JIVE. The topics ranged from low-frequency to mm radio astronomy, from connected element interferometers to very long baseline interferometry. The social events included a conference dinner at Westerbork, a visit to the LOFAR core, and a football match.

    Here you see the school picture, taken on the first day of the school at Westerbork. For the participants, the LOC, and SOC, it has been an intense, fruitful, and successful week. The ERIS LOC thanks all the people that contributed to the school.

    0 0

    © ASTRON

    Dr. Claudio Maccone, Technical Director of the International Academy of Astronautics (IAA) and a frequent visitor to ASTRON, was recently elected Chair of the IAA SETI (Search for Extraterrestrial Intelligence ) Permanent Committee. The primary goal of the IAA Permanent SETI Committee is to examine all aspects of possible future contact with extraterrestrial civilizations, with special reference to international issues and activities. These aspects include technical efforts to find evidence for extraterrestrial intelligence, as well as the social consequences of such a discovery. In addition, the Committee promotes the interest and eventual involvement of students in its work, primarily through education initiatives, the Internet, and the mass-media. In support of the Academy's advisory role to the United Nations, the Permanent Committee has developed international protocols for activities to be undertaken in the event of verified extra-terrestrial contact.

    Claudio (pictured above) succeeds Dr. Seth Shostak (SETI Institute) who faithfully chaired the SETI PC for many years. Dr. Paul Shuch was elected as the new vice-chair. Prof. Michael Garrett (ASTRON) was also elected as a new member of the SETI PC.

    The next meeting of the PC is scheduled to take place this week at the the 64th International Astronautical Congress, to be held in September in Beijing. One of Claudio's first challenges will be to promote adoption by the IAA, and eventually the UN, of the Committee's most recent update to these post-detection protocols.

    For more information, consult the SETI PC's public website at:

    0 0

    © UNAWE

    The newest addition to UNAWE's extensive astronomy education repository is "The Invisible Universe", a compilation of activity guides created in collaboration with ASTRON to introduce primary school students to the invisible world of radio and inspire them to develop a curiosity about the vast and wonderful Universe they live in.

    Since ancient times, people have been fascinated by the night sky, but only since the invention of the telescope in 1608 have we been able to study astronomical objects in detail. It has been an even shorter time that we've been able to look at the Universe in other types of light than visible. Radio, infra-red, gamma, UV and X-rays give astronomers a peek into a completely new world: the 'invisible' Universe. This means that radio astronomy is a relatively young science, and there is still much to be discovered. Unraveling all the hidden secrets of the Universe will still take many generations of astronomers. Therefore inspiring young children is essential to the future of space science. Luckily for us, the Universe sells the subject of astronomy all on its own!

    The activities in this guide are designed for students aged 8-12 years, and no prior knowledge of astronomy or the electromagnetic spectrum is required. Age range, duration, materials, step-by-step instructions and all necessary background information are included for each activity, in addition to the learning objectives so that teachers can match the activities to their national curriculum. Each lesson includes a selection of interactive activities along with the more traditional textbook questions to keep them engaging and fun.

    Download the activity guide in full from the UNAWE website ( and introduce your students to the Invisible Universe.

    0 0

    © Hiddo Hanenburg

    The mechanical design group of the ASTRON R&D department is designing housings for the AA antennas of the SKA MID frequency range. Since SKA will be located in a desert, the harsh environment has to be taken into account. Computational Fluid Dynamics analysis is performed to determine the influence of the Solar radiation on the temperature of the housing surfaces, and on the electronics inside. The maximum temperature affects the lifetime of these components. At night there is a strong radiative loss of heat to the clear sky. The large diurnal temperature variations have their influence on the electronics. For optimal signal stability and long calibration intervals, the temperature changes over time should be small.

    The picture shows a model of a "naked" tile in the Sun, i.e. without any cover, and at the hottest time of the day. The model consists of a ground-plane and simplified vivaldi antennas. The tile is placed on legs on the desert soil. In the analysis, the temperatures and air velocities are calculated over several days and nights in time steps of 6 minutes.

    The colors represent the temperatures of the surfaces of the antenna and the ground. The temperature of the legs is not shown, so these are gray. The temperature of the air is 34 degrees C. This is not shown in the picture. The direction and velocity of the air flow is shown as small arrows.

    Clearly visible are the hot surface of the soil and the cool shadow below the tile. The cooling effect of the air results in cool antennas, and cools the ground-plane with electronics to 40 C.

    The calculation time is about 22 hours and generates a data file of 183 GB.

    0 0

    © Roberto Pizzo

    LOFAR has just completed Cycle 0, its first operational observing cycle. A total of 2850 successful observing hours were delivered, including 94% (2250 hours) of the total time awarded to the 38 approved Cycle 0 user projects. Together with Cycle 0 observations, during its first operational Cycle LOFAR has also successfully observed 600 hours of non-Cycle 0 observations. Specifically, it has started and almost completed the HBA part of the MSSS survey. Moreover, it has observed several commissioning, as well as DDT (Director's Discretionary Time) projects.

    Cycle 0 has been an important learning experience for the Radio Observatory of ASTRON. The distribution of successful production observing with time is shown in the diagram. In this diagram, 100% would correspond to an absolutely perfect system running observations full-time without any gaps, maintenance, or development. The diagram illustrates that since the beginning of the Cycle, LOFAR operations have improved significantly in quality and efficiency. Several issues have been faced and, in most cases, they have been quickly resolved while the instrument continued to deliver scientific data to the users. During routine production weeks, the efficiency of LOFAR has attained that of many more mature observatories. Recently, the installation of COBALT - the new LOFAR correlator under development - into the observing system has caused some delays in the observing schedule. Therefore, the remaining 6% (120 hours) of Cycle 0 will be completed during Cycle 1, which has started already on November 15th 2013.

    From now on, there will be a regular half-yearly (semester) pattern of proposal and observing cycles, while work continues to expand the observing capabilities and make them more robust.

    0 0
  • 11/16/13--16:00: Ghost Nebula
  • © Albert van Duin

    This reflection nebula in Cepheus is named the Ghost Nebula, a very appropriately named object for the Halloween season.

    Its official names are Sharpless3-136 or VandenBergh-141. It is an isolated reflection nebula, about 2 light years across, located around 1200 light years from Earth. It got its unofficial name due to its spooky appearance, and the two waving ghostly figures left of the bright part in the image above.

    The dark dust cloud on the right is a Bok-globule designated CB230, it is collapsing and a binary star sytem is in the early stages of formation over there, just visible through the dust as a ruddy glow.

    The "amateur" image above totals 7 hours and 40 minutes of integration time. 4 x 10 minute integrations were made through each of the RGB filters, and 34 x 10 minute integrations were made through the luminance filter. All this was done on two separate nights in October, with a 40cm telescope, from Beilen, the Netherlands.

    0 0
  • 11/14/13--16:00: Nature pulls a fast one!
  • © Jayanne English (U. of Manitoba), Judith Irwin (Queen's U.), Richard Rand (U. of New Mexico) and collaborators in the CHANG-ES consortium, NRAO VLA, NASA WISE & Spitzer missions, SDSS, and NOAO.

    Sometimes initial impressions are deceiving! In the case of UGC 10288, what was once thought to be one galaxy is now known to be two very different superimposed galaxies. This new information has been obtained as part of an ambitious survey recently performed with the Karl G. Jansky Very Large Array (VLA), the "Continuum Halos in Nearby Galaxies: An EVLA Survey" (CHANG-ES) led by Judith Irwin (from Queen's University in Canada).

    Today's image reveals the actual situation. UGC 10288, the edge-on disk galaxy that dominates the field, is the nearer galaxy and was the target of the VLA observations. The background radio galaxy, seen in cyan colors, is a distant background radio galaxy that is totally disconnected from UGC 10288 (it is some 7 billion light-years more distant). In earlier observations these two galaxies blended into one, such that all of the light was thought to be coming from UGC 10288 alone.

    What may seem at first blush to be a mere curiosity is actually providing unique information about the nearer of the two galaxies. First of all, the previously determined physical properties are now known to be different (for example, the inferred star formation rate is now considerably lower). More intriguing is the rare opportunity to study weak magnetic fields in the foreground object based on the observed properties of the background object. In fact, the angular sizes and orientations of the two galaxies are highly fortuitous, possibly allowing a detailed study of the vertical structure of the magnetic field in UGC 10288. An early analysis, presented in an Astronomical Journal paper (here) that is now being published on this system, shows that the magnetic field of UGC 10288 probably reverses direction between vertical heights of 1.5 and 3.5 kpc above the disk. We are now working on a more sophisticated study of the system, using the Rotation Measure Synthesis technique that was developed here at ASTRON.

    Color codings: NASA's WISE (far-infrared; orange) and Spitzer (near-infrared; yellow) space observatories, the Kitt Peak National Observatory's 0.9m telescope (ionized hydrogen; rose), the Sloan Digital Sky Survey (optical; purplish-blue), and NRAO's VLA (radio; cyan).

older | 1 | .... | 4 | 5 | (Page 6) | 7 | 8 | .... | 71 | newer