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Articles on this Page
- 05/16/13--17:00: _Four score years ag...
- 06/03/13--17:00: _The GBT 350 MHz dri...
- 06/02/13--17:00: _Dwingeloo-live expands
- 05/30/13--17:00: _UniBoard accelerate...
- 05/29/13--17:00: _Today's Colloquium:...
- 05/28/13--17:00: _Arnold retires, at ...
- 06/04/13--17:00: _A new frontend for ...
- 06/05/13--17:00: _Today's Colloquium:...
- 06/06/13--17:00: _Royal Visit(s) to D...
- 06/12/13--17:00: _Today's Colloquium:...
- 06/11/13--17:00: _Nederlandse Astrono...
- 06/10/13--17:00: _Proper Motion of th...
- 06/09/13--17:00: _New LOFAR guides co...
- 06/13/13--17:00: _Bert Woestenburg re...
- 06/16/13--17:00: _SKA MFFA (mechanica...
- 06/17/13--17:00: _Astronomers use pre...
- 06/18/13--17:00: _Demonstration of dy...
- 06/19/13--17:00: _Behold, the first E...
- 06/20/13--17:00: _AERAP honours Arnol...
- 07/11/13--17:00: _The LOFAR Skyline
- 05/16/13--17:00: Four score years ago...
- 06/02/13--17:00: Dwingeloo-live expands
- 05/30/13--17:00: UniBoard accelerates radio astronomy
- 05/28/13--17:00: Arnold retires, at least formally
- 06/04/13--17:00: A new frontend for APERTIF
- 06/06/13--17:00: Royal Visit(s) to Dwingeloo
- 06/11/13--17:00: Nederlandse Astronomen Conferentie 2013
- 06/10/13--17:00: Proper Motion of the Young Pulsar in the Supernova Remnant 3C58
- 06/09/13--17:00: New LOFAR guides complete training course
- 06/13/13--17:00: Bert Woestenburg retires with moderate noise
- 06/16/13--17:00: SKA MFFA (mechanical) prototypes at the WSRT
- 06/17/13--17:00: Astronomers use precision pulsar positions to break record
- 06/18/13--17:00: Demonstration of dynamic Bandwidth on Demand at TNC2013
- 06/19/13--17:00: Behold, the first EVN Uniboard Fringes!
- 06/20/13--17:00: AERAP honours Arnold van Ardenne
- 07/11/13--17:00: The LOFAR Skyline
© JIVEHappy birthday! Eighty years ago (on May 5, 1933) the first radio astronomical publication appeared on the front page of The New York Times. It was about the detection of radio waves from our own Galaxy by Karl G. Jansky.
Like Hamlet pondering the jester's scull, a newspaper page like this makes one dwell on the transience of human affairs. The other items on the page, however momentous they may have seemed at the time, mean very little to the vast majority of today's twittering punters. Incredibly, even Sir Alex Ferguson, Michael Jackson and Pim Fortuyn will be forgotten one day. And when, sooner rather than later, we leave behind a ruined and exhausted planet, it will insult our memory by regenerating very quickly, obliterating all traces of our brief stewardship.
So, when we go gently into the night, raging against the dying light(*), our only hope of a lasting monument to our species may be our cumulative scientific understanding. What else? Thanks to careful observations, combined with the truly divine gift of mathematics, we are able to rise above the stifling embrace of human measure. With any luck, and a lot of hard work, this may eventually earn us a better footnote in the Hitchhiker's Guide to the Galaxy(**). We might yet be proud of having belonged to a species that came to understand the Universe(s).
In the picture above, only the top-left article points in that direction. But at least there is one, and on the front page of the New York Times, no less. So let us continue the noblest of quests, as sensibly as we can.
(*) Dylan Thomas, of course.
(**) The current one is "mostly harmless"
© ASTRON/ESO/AuthorsIn 2007 a global team of astronomers including ASTRON scientists Hessels, Kondratiev and van Leeuwen used the Green Bank Telescope (USA) for a 1,000-hr, 10,000-sq. degree pulsar survey (Paper I, ApJ 2013). This 350-MHz GBT 'drift-scan' pulsar search discovered 31 new pulsars, 7 of which are recycled pulsars. Notable systems, described in paper II, ApJ 2013, include PSR J2222-0137, a 32.8 ms pulsar at a very low DM of 3.27 pc/cc, which is in a 2.4 day orbit with a minimum companion mass of 1.11 M sun. It is most likely a white-dwarf-neutron-star system or an unusual low-eccentricity double neutron star system. PSR J1923+2515 is an isolated MSP with a 3.8-ms spin period (left panel). Finally, PSR J0348+0432 (middle panel) is a partially recycled pulsar with a white dwarf companion in a short orbit.
From follow-up optical observations, that latter millisecond pulsar, J0348+0432, turned out to a very massive, 2.01 solar mass neutron star in a highly relativistic orbit (artist impressions, right-most panel; Paper III). The high pulsar mass and the compact orbit make this system a sensitive laboratory of a previously untested strong-field gravity regime; a results that warranted publication in Science recently. Many physically motivated extensions to general relativity (GR) predict significant deviations in the properties of spacetime surrounding massive neutron stars. Thus far, the observed orbital decay agrees with GR, supporting its validity even for the extreme conditions present in the system. The resulting constraints on deviations support the use of GR-based templates for ground-based gravitational wave detectors. Additionally, the system strengthens recent constraints on the properties of dense matter and provides insight to binary stellar astrophysics and pulsar recycling. The press release for this paper includes a dynamic video impression of this extreme system.
© Alec Meijerink (CSG Bogerman)Despite its respectable age, the Dwingeloo Telescope still looks impressive and is still very much alive!
Several years ago, we started an outreach project named Dwingeloo-live, where high-school students could come to ASTRON and use the Dwingeloo telescope themselves to take data from a bright pulsar, similar to Pulse@Parkes (http://outreach.atnf.csiro.au/education/pulseatparkes ). We set up a website that allows the students to analyze the pulsar data and to find the period and dispersion measure (http://www.astron.nl/onderwijs ).
Now we have expanded Dingeloo-live to find out if students from a Technasium (http://www.technasium.nl ) can use Dwingeloo-live to find the pulsar's period derivative and look for time-variations in the dispersion measure.
The first group, from CSG Bogerman in Sneek, has visited ASTRON on a nice spring day for a meet and greet with the telescope. They will start working on recorded data until the recently refurbished telescope is in full operation again.
© ASTRONIn the first issue of 2013 of the NWO-magazine Hypothese, Arpad Szomoru (JIVE) and Andr� Gunst (ASTRON) gave an interview about UniBoard, a multifunctional data processing board for radio astronomy and sensor technology purposes. UniBoard was developed in the European project RadioNet FP7 and was led by JIVE.
You can read the article on http://www.nwo.nl/over-nwo/voorlichting-en-communicatie/publicaties/hypothese/hypothese---2013---1.html on page 22-24.
© Fatemeh TabatabaeiRecent studies of the correlation between the nonthermal radio continuum and thermal far-infrared (FIR) emission from galaxies shows variations of this correlation as a function of not only the star formation but also the magnetic fields, gas density, and heating sources of dust; i.e., the ISM properties. This suggests that the local radio-FIR correlation could be used as a probe to the interplay between the star formation and the ISM. The interplay between the star formation and gas, as the important ISM component in terms of mass, is partly studied through scaling relations such as the well-known Kennicutt-Schmidt law. I will address the interplay between the star formation and the magnetic fields, as the important ISM component in terms of energy density, by presenting a scaling relation between the star formation rate surface density and the magnetic field strength in galaxies. The effect of the environment of a galaxy on this empirical relation will be further discussed.
The image shows how star formation and magnetic fields control the radio-FIR correlation in the fireworks galaxy NGC6946.
© variousToday we mark the formal retirement of Arnold van Ardenne, a giant in the field of radio astronomy technology. For several decades now, he has played a leadership role in the field's development. His list of contributions is long, and underpins the recent conclusion by an international evaluation panel that ASTRON is "re-inventing" radio astronomy.
For example, in the early 1980s Arnold used NASA's new Tracking and Data Relay Satellite System to demonstrate for the first time how satellites in low Earth orbit can be used to do VLBI. And he played an important role in the instrumentation for the JCMT submm telescope on Hawaii. In the early 1990s, after returning from industry to lead ASTRON R&D, he embraced the refurbishment of the Westerbork Synthesis Radio Telescope and oversaw its return to a front-line facility.
Perhaps most importantly, he was among the first to understand, amid much skepticism from astronomical and technical colleagues, that radio astronomy would need the Square Kilometre Array (SKA) project, and that the design and development required would yield important spin-off and scientific results along the way. He realized that new design tools and innovative technologies would be required, and in the mid-1990s he hired world-class antenna and IC teams to take up the challenge.
He made certain that ASTRON's new (1996) building in Dwingeloo included the engineering infrastructure for testing the new designs, both in radio and optical astronomy. By the early 2000s, Arnold's engineering laboratory would be known the world over for its consistently innovative R&D in support of astronomy. In the ensuing decade, ASTRON engineers produced state-of-the-art instruments for ESO and for NASA, designed and built LOFAR, and took a leading role in R&D for the SKA. His European SKADS programme generated intense continent-wide activity, while forging many valuable contacts between SKA contributors.
One secret of this success may be found in the engineering culture he brought to ASTRON, following his years as R&D executive at the giant Ericsson technology company. Arnold worked tirelessly to achieve the right balance between the rather disparate cultures of academia and of industry best-practice engineering. That he generally managed the resulting tensions well, realizing the intended synergy, is demonstrated by the many successful forefront instruments that are operational on telescopes both European and foreign.
Enjoy your retirement, Arnold, although it is unlikely that this marks the end of your contributions. You have set a high standard for future generations of radio astronomy ingenieurs. Moreover, there are only a handful of labs that can build SKA, and you have built one of them.
© ASTRONThis image presents the completely redesigned APERTIF element assembly. Each Phased Array Feed that will be installed in the WSRT will consist of 121 of these active antenna elements.
The element combines several functions, such as the antenna, low noise amplifier, limiters to protect gain stages for nearby GSM, an equalizer to correct gain slopes, filtering and a lot of gain. This gain is required to compensate for losses and hide the noise contribution of the A/D converter.
The hostile RFI environment at the WSRT posed the largest design challenge. A very strong suppression of out-of-band signals is required, especially of the digital television transmitters (DVB-T) from Smilde. The OFDM modulation scheme of only one such transmitter produces more than 2000 carriers in an 8 MHz band. If not sufficiently suppressed, these pseudo noise like modulations will mix with other transmitters and cause wide-band interference over almost the entire APERTIF band. The presented design realizes more than 100 dB of suppression and successfully mitigates the DVB-T issue. The board has a gain of 50 dB and a noise temperature of 45 K for a single active element. The design is built using modular blocks. By measuring and simulating these blocks, a good control of the overall complex design is maintained. It also gives possibility to reuse the blocks in another design or project.
For APERTIF, around 1,500 of these elements will be needed. This makes that the board must be mass producible. So all manufacturing details must be correct. For example, the component pad shapes must be designed according the IPC standard. The design itself is evaluated using statistical simulations and a number of boards are going to be thoroughly tested to see how they perform under (eg. thermal) stress.
© Dan HarrisWe argue that most observations of extragalactic jets do not directly inform us of basic jet physics. Rather, the radiation we see comes from plasmas which are produced by the conversion of jet power to relativistic electrons and B fields. What we want is a determination of the underlying electron spectrum, N(E), over as wide a range as possible for the emitting regions and thereby, gain insights into the conversion process (shocks and magnetic reconnection). For powerful quasar jets, the primary X-ray problem is our uncertainty as to the emission process: if the X-rays are from synchrotron emission we learn about extremely high energy electrons (gamma ~ 10^7), whereas IC/CMB models require large numbers of low energy electrons (gamma ~ 100). LOFAR, with arcsec resolution at low frequencies, should permit us to track N(E) to energies low enough so as to decide if the extrapolation from higher energies (a necessary ingredient of IC/CMB calculations) is correct or not.
The River Analogy for Relativistic Jets: Imagine a jet is like a river; smoothly transporting energy. When there is a rock near the surface or a waterfall, white water occurs: a fraction of the river's energy is converted to random motion. When we 'see' a jet, we are viewing only the white water, not 'the jet' itself.
Editor's note: Dan was one of our first six post-docs, back in the late 70s. In those days, SRZM (ASTRON) was not supposed to do any science. We finally persuaded the universities that a few astronomers would help us build better instruments. The first batch all went on to greatness.
© ASTRONOn May 28th 2013, King Willem Alexander and Queen Maxima visited the northern provinces Groningen (in the morning) and Drenthe (in the afternoon). During a lunch with some 100 local and regional dignitaries, ASTRON Director Prof Mike Garrett managed to secure a brief audience with the Queen, inviting her to open the made-over ASTRON headquarters on the edge of Dwingeloo Heath.
In the afternoon, ASTRON presented itself on the Brink of sunny Dwingeloo, together with about 20 other stands and music groups. On display were pictures of (some of) the many Royal Visits that mark the prominent Dutch role in radio astronomy: Queen Juliana opening the 25m Dwingeloo telescope in 1956 (left), and the 3km Westerbork telescope in 1970 (right), and Queen Beatrix opening the 1000km LOFAR telescope in 2010 in Exloo (middle).
These photographs served as backdrop for a technical project carried out by four primary school pupils. The children made small scale-models of LOFAR antenna fields (see picture), demonstrating that using a larger number of antennas increases the sensitivity, and thus our ability to unlock the secrets of the Universe.
After the demonstration, the Royal Couple graciously paused near the 1956 picture, which was taken as prof Oort spoke the immortal words: "Zoudt U op deze knop willen drukken, Majesteit" (Wouldst Thou press this button, Your Majesty?). A worshipful but alert ASTRON operative took this opportunity to invite the King to visit ASTRON in the near future, to close the historical cycle by pushing the same button again, starting the second life of the completely refurbished Dwingeloo telescope.
No dates were fixed, of course, but the seeds have been sown.
© The Dark Energy Survey collaborationIn this talk I will show the aspirations that we have in probing the Dark Universe with optical imaging surveys, including the hurdles and the statistical advantages of such surveys. Specially I will focus on the results that we have in the path to the Dark Energy Survey, including the science verification data from DES. The survey proper will start in Oct 2013 and span 5 years. I will give an update on the plans and prospects.
This image focuses on the Fornax cluster, some 60 million light years from Earth. The galaxies in the image seem to cluster together in the upper-right portion of the image, where the centre of the cluster is located. The particularly prominent spiral structure in the lower section is NGC 1365.
© ASTRONAn enthusiastic ASTRON and JIVE delegation has attended the Dutch Astronomy Conference (NAC). This year it was held on May 15-17 in Belgium (Lommel, actually just a few hundred meters from the border) and was organised jointly by the astronomy institutes of KU Leuven and Ghent University. The location, Center Parcs "De Vossemeren", would have been perfect if the weather would have helped a bit more. It was a very wet NAC.
The ASTRON-crew was quite prominent in the program with talks and a number of posters. Results from LOFAR were also presented in a number of talks.
The rain and some particularly challenging talks created a few tough moments, but apart from this, the meeting was very "gezellig", as a NAC should be!
As per tradition, a few prizes were awarded: the ''Willem de Graaffprijs'', for outreach activities, was awarded this year by Stichting De Koepel to Peter Barthel (Groningen); the poster price was awarded to Mina Koleva (U.Ghent) and the ''Pastoor Schmeitsprijs'', for outstanding contributions by a young astronomer, to Rychard Bouwens (Leiden) for his work on high-redshift galaxy evolution.
Next year the NAC will be organised by Leiden (but the year after it could be our turn!)
© Michael Bietenholz (HRO/York University)Though the supernova remnant 3C58 had long been known as a pulsar wind nebula, the pulsar was not discovered until 2002 in both X-ray and radio. PSR J0205+6449 is at a distance of about 3.2 kpc, has a period of 66 ms and quite low pulse-averaged flux density of only 45 �Jy at 1.4 GHz, and is one of the most energetic, and almost certainly of the youngest known pulsars. Pulsar wind nebulae provide important diagnostics for young pulsars, giving insight into the winds which carry away the pulsar spindown energies. Knowing PSR J0205+6449's proper motion is important for determining the nature of its interaction with its surrounding nebula. It is also particularly interesting because of the unsettled question of 3C58's age: its traditional association with the supernova of 1181 A.D. has recently been repeatedly questioned. In particular, the pulsar is offset from the center of the thermal X-ray shell. If the pulsar was at the center of the X-ray shell in 1181 A.D., its proper motion should be ~30 mas/yr, easily measureable with VLBI observations.
We employed a novel observing technique in our two-epoch VLBI observations of this young pulsar. We used Green Bank Telescope (USA) simultaneously in the VLBI array and for single-dish pulsar timing using the Spigot or GUPPI backends. The high timing noise of this young pulsar and its glitching nature precludes the determination of the proper motion from the pulsar timing and makes necessary to measure pulsar's period at the epochs of VLBI observations. We derived the position of the pulsar accurate at the milliarcsecond level and determined its proper motion, corresponding to a projected velocity of only 35 km/s for a distance of 3.2 kpc, that is quite low compared to the velocity dispersion of known pulsars of ~200 km/s. We estimated pulsar position at birth, and it seems more likely that age of PSR J0205+6449 and 3C58 is several thousand years, rather than associated with SN 1181 A.D.
These results are published in the paper by M. Bietenholz, V. Kondratiev,
S. Ransom, P. Slane, N. Bartel, and S. Buchner in MNRAS.
The main figure represents a 1.4-GHz VLA radio image of 3C58 from Bietenholz (2006). The cross sign shows the present location of PSR J0205+6449, while the two plus signs mark two possible birth locations: at 1181 A.D. and at 5000 BC. Plots on the right show the average pulsar profile at two epochs of observations.
© ASTRONOn Saturday 20 April near the LOFAR telescope in Exloo, after two months of training, seventeen volunteers became official tour guides to the LOFAR core area. The mayor of Exloo, Marco Out, handed the LOFAR guides their certificates after they gave their first official tour through the LOFAR core and the associated nature preserve.
The training was set up by a group called the LofarTafel (a group of entrepreneurs in Exloo promoting LOFAR in the region), and by the foundation Het Drentse Landschap (the organisation for nature and landscape preservation in Drenthe), and is supported by ASTRON.
These organisations, but also local entrepreneurs, regularly receive questions from tourists and visitors in the area whether tours at the LOFAR telescope are possible. This gave rise to the idea for a course in which volunteers can be trained to do presentations and tours about the LOFAR telescope and the surrounding nature area.
The LofarTafel started the course in the beginning of this year. ASTRON supports the initiative by informing the guides about the LOFAR telescope and all its facets, and helping them with questions and materials such as photos and presentations.
The volunteers are trained to serve a broad audience consisting mainly of tourists and passersby in the area. The LofarTafel ( http://www.lofarzone.nl ) is coordinator of the project and organizes the visits to the telescope, together with ASTRON.
© ASTRONToday, 14 June 2013, ASTRON's most respected low-noise specialist retires. The picture shows Bert (right) together with another low-noise receiver colleague Bou Schipper (rtd) and our former colleague Andre Kokkeler (now teaching at Twente University).
Bert was educated as a microwave ingenieur in Leiden and Twente University. He embodies the temperament and knowledge that are needed to create microwave amplifiers for Radio Astronomy with the highest reliability and lowest noise. Initially, he built cooled and uncooled receivers for the cutting-edge Dwingeloo and Westerbork cm radio telescopes. Along the way he also ventured into the field of (sub)millimeter receivers. The somewhat grainy inset on the right depicts Bert in 1985 in Granada (Spain), working for the JCMT in Hawaii together with his then boss Jean Casse and Arnold van Ardenne.
Since low noise is in his character, it is perhaps surprising to hear that the same Bert used to play the guitar and was the lead singer in a rock band, where low noise is less of a priority.
But that is a long time ago and we now recognize his qualities in all the (close to a hundred) low-noise amplifiers in the WSRT Multifrequency frontends! On the whole one can say that Bert was invisibly essential(*) for many excellent observational results!
As Bert also works on future systems like APERTIF and the SKA (see inset on the left), it is wonderful that he will continue to contribute for a while to the lowest noise Aperture Array tile.
All the best Bert!
(*) Invisibly essential, the usual fate of hardware ingenieurs
© ASTRONOne may (mechanically) design an instrument with great care and still there are many aspects that are difficult to predict. Things like dust, dirt, vegetation, water, bugs, rodents and soil variations. The success or even failure of the design may depend on them. Field prototypes are the answer. They will experience all these aspects and probably even some unexpected ones. This approach allows the environment to play its part in the development of the instrument. After a few iterations, it should be fit to be operated successfully over its life-span.
Taking this development approach one step further, we are placing several conceptually different prototypes in the field, letting the environment "decide" which one is most suitable. The idea is to incorporate as many different design features as possible in a few carefully defined prototypes. In this case there are four, with varying levels of protection. Two of them have only a rain and solar cover, while the delicate electronics are protected locally by special coatings. Another prototype resembles the LOFAR HBA with its insulated housing, made of packaging material. The fourth is fully closed and made of low cost plastics.
Three out of four of these prototypes are now built. They are subjected to the first series of tests in the WSRT "bouwhal"�, before being placed in the open air. The closed prototype will follow in a few weeks time.
© Astron & Bill Saxton, NRAO/AUI/NSFAn international team of scientists led by astronomer Adam Deller (ASTRON) have used the Very Long Baseline Array (VLBA) to set a new distance accuracy record, pegging a pulsar called PSR J2222-0137 at 871.4 light-years from Earth. They did this by observing the object over a two-year period to detect its parallax, the slight shift in apparent position against background objects when viewed from opposite ends of Earth's orbit around the Sun. With an uncertainty less than four light-years, this distance measurement is 30 percent more accurate than that of the previous-best pulsar distance. The VLBA observations were even able to discern the orbital motion of the pulsar around its as-yet undetected companion object, despite this motion being no larger than a small coin observed at a tenth of the distance to the Moon. The results of the research have been published in The Astrophysical Journal.
By showing that PSR J2222-0137 is 15% closer than previous estimates, this impressive achievement can advance our understanding of the system. With the distance to the pulsar pinned down, proposed highly sensitive visible-light observations should determine the nature of the undetected companion. If no source can be found, the companion must be a neutron-star, while a white-dwarf companion will show up as a faint optical source.
The accuracy of the new measurement promises to help in the quest to detect the elusive gravitational waves predicted by General Relativity. By monitoring an array of pulsars across the Milky Way galaxy, scientists hope to measure the distortions of space-time caused by the passage of gravitational waves. Knowing the distances to these pulsars extremely precisely can improve the sensitivity of the technique to detect individual sources of gravitational waves. The VLBA is operated by the National Radio Astronomy Observatory (NRAO).
Caption to the image: Illustrating trigonometric parallax: the VLBA can measure the slight apparent shift in the position of an object as seen from opposite sides of the Earth's orbit. The size of this position shift is dependent on the distance of the object from Earth. Credit: Bill Saxton, NRAO/AUI/NSF.
© JIVE / NEXPReSLast week at the TERENA Networking Conference 2013 in Maastricht, Paul Boven (JIVE), Radek Krzywania (Poznan Supercomputing and Networking Centre) and Tangui Coulouarn (Technical University of Denmark) gave several demonstrations of practical use of dynamic, on-demand circuit creation across European NRENs for the purpose of transferring radioastronomy observation data. These demos showed the creation of multiple international cross-domain paths from the radio-telescopes at Torun and Jordell Bank.
The high bandwidth generated by e-VLBI observations is best transported over dedicated connections. Currently, static (always-on) lightpaths are in use for e-VLBI, even when no observation is running. The Bandwidth-on-Demand service over international distances would allow for a more efficient and flexible network usage for e-VLBI.
The NSI protocol is a new standard developed in the OGF, that allows the creation of such international paths, regardless of heterogeneous environment constraints (e.g. different transport technologies, incompatible provisioning tools). NSI has been adopted by the GÉANT BoD service and multiple European NRENs. Network domains involved in the demonstration are using different network provisioning tools (e.g. OpenDRAC, AutoBAHN) with NSI interfaces attached, enabling inter-domain communication and the automated creation of international lightpaths upon request from the end-user.
The demos not only presented the creation of circuit, but gave a background on how NRENs and end-users are able to collaborate and integrate various services (e.g. provisioning, monitoring, topology information exchange) in automated manner, delivering resources for scientific community in a fast, yet reliable way. During the demos, we presented the advantage of dynamic provisioning over statically configured circuits.
© JIVE UniBoard teamLast Friday, scan 11 of the L-band NME N11L4 was correlated on the UniBoard EVN correlator.
A single 8 MHz subband from three stations was processed, with an integration time of 0.25 s and a frequency resolution of 1024 spectral channels across the band.
The plot, amplitude versus lags, shows two cross- and two auto correlations. The cross correlation fringes are not centered because of uncorrected clock offsets, however, they appear at exactly the predicted positions, as determined by running the JIVE SFXC software correlator as reference.
Fringes were stable throughout the ~10 minutes worth of data, proving the functionality of the delay correction and phase model.
This is a very important milestone in the development of the UniBoard next generation EVN correlator. Although some bug fixing will undoubtebly still be needed, we are now moving towards the actual commissioning phase.
The photo shows the happy JIVE UniBoard team, in front of the (new) correlator. Note that the two UniBoards currently installed will have four times more processing power than the entire MarkIV hardware correlator, at 20 times lower power consumption.
The team, from left to right: Harro Verkouter, Sergei Pogrebenko, Jonathan Hargreaves, Salvatore Pirruccio, Arpad Szomoru and Des Small.
© NL SKA OfficeThe African-European Radio Astronomy Platform (AERAP) has awarded Arnold van Ardenne (left) a certificate in recognition of his outstanding engagement and lasting contribution to AERAP. The certificate was presented at the one-day symposium, "Reinventing Radio-Astronomy: Technologies that made a Difference" on May 29th, 2013 at ASTRON. This was organized to mark Arnold's 65th birthday.
The overall goals of AERAP are to leverage radio astronomy, advance scientific discovery, improve knowledge transfer and stimulate competitiveness across both continents. Thus it aims to enable effective dialogue to build a shared vision for international cooperation in radio astronomy.
Prof van Ardenne is coordinating the thematic priority Instrumentation, Research and Development� of the AERAP Framework Programme for Cooperation and has also been a key participant in nearly all AERAP events.
The certificate was presented by Declan Kirrane (right), Managing Director of ISC Intelligence in Science, a specialised science, technology and R&D public affairs firm based in Brussels. ISC Intelligence in Science does the coordination of AERAP as one of its initiators, together with the South African Mission to the EU.
© MCCIf the grass were just a little shorter, you would be able to see the dense collection of LBA and HBA antennas on the LOFAR "Superterp", the heart of the largest telescope in the world. As it is, you just have to trust us that it's really there, quietly unlocking the secrets of the Universe.
This is the way the Dutch like to do things: Serving humanity with as little fuss as possible, while preserving our iconic skyline. That is why we use aperture arrays, which are less ostentatious than large, clumsy dish antennas, and easy to hide(*). Moreover, aperture arrays offer a broader, clearer, more versatile vision of the sky, and avoid tiresome diffraction effects. Best of all, they do not have any moving parts, which only cause more fuss, and are less green.
We are serenely confident that LOFAR will make many important discoveries. The latest images are already close to the thermal noise limit (which is like the grass that hides the telescope). This feat took us many years with earlier telescopes, and is still rare in the world. But we fervently hope that all the noisy acclaim, the hoopla, and the inevitable prizes, will be absorbed by our foreign users, who seem to crave that sort of thing.
(*) For this reason, the 25m dishes of the Dwingeloo and Westerbork telescopes were hidden in the woods, and painted in camouflage colors.