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- 11/01/15--16:00: _TV: Zapp Wetenscha...
- 11/02/15--16:00: _Neighbours
- 11/03/15--16:00: _LOFAR Holographic S...
- 11/04/15--16:00: _Today's Colloquium:...
- 11/05/15--16:00: _In memoriam Bill Er...
- 11/08/15--16:00: _LFAA AAVS1 Detailed...
- 11/09/15--16:00: _LOFAR discovers mys...
- 11/10/15--16:00: _First 2 Gbit/s e-EV...
- 11/11/15--16:00: _Today's Colloquium:...
- 11/12/15--16:00: _Dominic Dirkx, PhD ...
- 11/15/15--16:00: _First Light of the ...
- 11/16/15--16:00: _Software Architectu...
- 11/17/15--16:00: _In Memoriam: Prof. ...
- 11/18/15--16:00: _Today's Colloquium:...
- 11/19/15--16:00: _Broadband radio emi...
- 11/23/15--16:00: _First bright fireba...
- 11/22/15--16:00: _Still going strong:...
- 11/24/15--16:00: _Tonight on TV: The ...
- 11/26/15--16:00: _Three new LOFAR sta...
- 11/25/15--16:00: _Today's Colloquium:...
- 11/01/15--16:00: TV: Zapp Wetenschapsweek: "Ontdek de Ruimte"
- 11/02/15--16:00: Neighbours
- 11/03/15--16:00: LOFAR Holographic Station Calibration
- 11/05/15--16:00: In memoriam Bill Erickson 1930-2015
- 11/08/15--16:00: LFAA AAVS1 Detailed Design Review
- 11/09/15--16:00: LOFAR discovers mysterious structures in our Galaxy
- 11/10/15--16:00: First 2 Gbit/s e-EVN fringes
- 11/11/15--16:00: Today's Colloquium: Big and young SMBHs in the early Universe
- 11/12/15--16:00: Dominic Dirkx, PhD Cum Laude!
- 11/15/15--16:00: First Light of the APERTIF Correlator!
- 11/16/15--16:00: Software Architecture Course at ASTRON
- 11/17/15--16:00: In Memoriam: Prof. Rod Davies CBE, FRS (1930-2015)
- 11/18/15--16:00: Today's Colloquium: How to SPAM the 150 MHz sky
- 11/19/15--16:00: Broadband radio emission from Kardashev Type II civilisations.
- 11/23/15--16:00: First bright fireball captured by BINGO!
- 11/22/15--16:00: Still going strong: Henk (94) and Willy (89) Sieders
- 11/24/15--16:00: Tonight on TV: The last episode of Klokhuis Heelal
- We next work this out in a first script, seen top left, where (roughly) I do content; the editor does content, storyline and writing for the target audience; and the director thinks about which content has good visuals.
- Top-right you see the next step, were the director thinks through and visualizes all the shots and motions. The producer then makes these happen on location or in the studio.
- He knows all the ropes -- but just outside the shot he actually holds them too, as you can see from our zero-gravity capes (bottom left). I had to veto their flapping in space. This is the part with most people involved: presenter, sound, video, production, all in a small, hot studio; or on a freezing cold night on the heath.
- Then, after an intense period of editing, sounds and video effects, the final result appears! You can see our final fly-by of Titan bottom right.
- 11/26/15--16:00: Three new LOFAR stations will connect to the ILT on 1 January 2016
- The Rector of the hosting university and many professors
- The president of Olsztyn and other municipal authorities
- Members of the POLFAR consortium
- Companies that contributed to the realization of the stations
- Representatives from ILT/ASTRON/AstroTec
- The Polish LOFAR community is organized in POLFAR. Within this consortium of universities and research institutes, the three LOFAR station owners are collaborating in a working group, POLFARO. The legal representative of POLFARO is the University of Warmia and Mazury in Olsztyn. ILT signed the contract not with the individual station owners, as was done in Germany, but with POLFARO.
- The agreement is for five years, starting on 1 January 2016, and described details on signal data transfer, data ownership and data rights, and the annual contribution from POLFARO to ILT, which is partly an in-kind contribution in the form of a Long Term Archive of 2 petabyte of data per year.
© NTR/ASTRONEvery night this week (2-6 Nov) at prime time, 19:25, NTR will broadcast TV show "Ontdek de Ruimte" ("Discover Space"). It is presented in the studio by Netherlands/ESA astronaut Andr� Kuipers and on the road by presenter Bart Meijer. If you want, you can take a look at the trailer or the mini making of.
The show is part of ZAPP, the television block for kids and young adults on the Netherlands public broadcasting system NPO. This show is aimed at older kids and adults, and is part of the ZAPP Science Week.
Episode one of the show, airing tonight, 19:25 on NPO3, covers "Super telescopes". It thus prominently features both Westerbork and LOFAR. The report was filmed over two days last summer. As it was shot through a 3-axis steady cam it looks amazingly smooth. These must be some of the prettiest pictures ever taken of our pride telescopes.
The complete series will remain online on schooltv.nl, the free Dutch "Netflix" of kids informational programs.
© Photo: Paul BovenFollowing a long tradition, the one-day Neighbourhood Meeting between Bonn and Dwingeloo VLBI astronomers was held on 28 October 2016 at the Astron/JIVE headquarters. This was the eighth of a series of meetings organized (almost) every two years. The focus is on the exciting new VLBI science results, presented by (mostly) the young postdocs and PhD students. But all of this in a very friendly atmosphere, and followed by a fun dinner/borrel.
P.S. Please stop complaining about missing the football game. When was the last time we won a single match?
© (c) Astron 2015Over the summer development began on applying holography to improve LOFAR's station calibration. Current calibration methods require 24 hours of all-sky imaging followed by an equal period of post-processing, making station calibrations a costly ordeal. So far initial holography trials have already proven to be highly efficient, allowing one to both observe and reduce the data for the entire LOFAR array within a day, a significant improvement over current methods. At this point we are working on applying the derived solutions produced by our holographic observations to LOFAR's calibration tables.
The following animation gives a quick look at the current state of the project. Presented is the DE609 HBA-field, part of an at the time known poorly calibrated LOFAR station. (Note: The colormap of the top left and middle figures encodes complex values as red = +real, green = +imaginary, purple = -real, and cyan = -imaginary) The figure's two rows show the aperture space [top row] and the beam space [bottom row] that are mutually related through a Fourier transform. The left column shows the reduced data produced by a holographic observation. The beam visibilities [bottom left] show the station’s beam on the sky sampled by digital sub-beams, while its Fourier transform [top left] reveals the complex voltage distribution over the station. The middle column shows the least-squares fitted beam model while the right column shows the residues between the observed data and model. For most frequency sub-bands the beam model and residues show a good fit reaching a couple percent error. However, for some sub-bands both the observations and model fail, notably 220 MHz and 227 MHz that coincide with digital radio broadcasts.
© David MulcahyMagnetic fields are an essential part of the interstellar medium, both within our own Galaxy and in other external star-forming galaxies. In spiral galaxies these fields are thought to arise due to differential and helical turbulence: the so-called ''dynamo model''. They govern the propagation of relativistic cosmic rays, controlling their density and distribution, and dominate the energy budget in the extended galactic disk.
There is increasing evidence that magnetic fields can extend deep into the intergalactic space; however as it is far from regions of acceleration, the synchrotron emission is weak due to lack of cosmic rays electrons which suffer from various loss processes. Fortunately, low energy electrons which emit emission at low frequencies suffer less from energy loss processes and are expected to travel further, especially in the presence of ordered magnetic fields.
The first part of this talk will present low frequency radio observations of the face-on galaxy, M51, from the LOFAR telescope. In combination with novel theoretical models of cosmic ray propagation, I will address multiple outstanding questions in galactic astrophysics: how far do galactic magnetic disks extend and what is their structure; what is the dominant mechanism of cosmic ray propagation in these regions? Using these theoretical models, the cosmic ray confinement time within the galaxy can be accurately calculated.
In the second part of this talk, I shall present new JVLA observations of the face-on spiral galaxy, NGC 628, at 2-4 GHz. The observations aim to increase our understanding of the disk-halo interaction which is vital to explain the evolution of spiral galaxies. Studying a face-on spiral galaxy like NGC 628 helps the separation of magnetic field components in 3D. Thus through the technique of Rotation Measure Synthesis, any Faraday rotation observed is due solely to the vertical magnetic field. This would help find turbulent magnetic fields being carried out from the disk and would provide an important mechanism for the dynamo to amplify the ordered magnetic field without quenching.
© NNEarlier this fall, Bill Erickson died at his home in Tasmania. Astron has known him for more than half a century since he worked in Leiden in 1963-1964, heading the exploratory phase in the development of a Benelux Cross Antenna whose concept was later abandoned in favour of the WSRT. He visited Dwingeloo and Leiden many times since and spent a three-month sabbatical in Dwingeloo in 1983.
Bill was a quiet, soft-spoken man whose influence was nonetheless considerable, owing to creative ideas and his enthusiasm to participate hands-on in the labour of putting them to practice. He was also an outdoors man who greatly enjoyed the remote natural environments where these endeavours took him. All of this made him a very effective teacher for many generations of students at the University of Maryland.
He was the architect of the Clark Lake array in California where the first-ever synthesis observations at the low end (6-60 MHz) of the radio window were made. The instrument did not make it through its early commissioning, though: In the fierce competition with other developments, funding was prematurelly cut off. Bill recovered from this disappointment by inspiring and actively participating in the development of the VLA 74 MHz system, the first instrument to undertake systematic synthesis observations below 150 MHz. Experience with this system was gratefully used in the eventual design of LOFAR.
In the 1980s he moved from Maryland to Australia, his wife Hilary's home country, settling on a small island off Tasmania. From there they commuted annually for a few months to a mobile home on the property of one of his former students (Bob Hanish and Susan Neff, who have also been postdocs at Dwingeloo: it's a small world). There they worked at Maryland and the Goddard Space Flight Center, where Hilary was employed as a solar-particle physicist.
They regularly traveled to Europe where Hilary collaborated with a group at Kiel, Germany, visiting us at Dwingeloo on the way. We had the pleasure of hosting them on most of these occasions. In 1999 we traveled together to Northern France to (90 percent unsuccessfully) watch the Solar eclipse.
In the early 2000s he took part in the conceptual development of an international synthesis array for frequencies down to tens of MHz. The international cooperation broke down, but demonstrators were built independently in New Mexico and South-West Australia, while Astron obtained funding for the bold step of constructing a fully-fledged instrument (LOFAR) in the Netherlands.
Bill finally retired from the international scene, but kept observing the Sun from his backyard with a home-built 26 MHz array. It was a privilege to have known him.
© ASTRONDuring a two day meeting on week 42, we enjoyed the Detailed Design Review (DDR) for the ApertureArray Verification System 1 (AAVS1) for the Low Frequency Aperture Array (LFAA) Element Phase 1 of the Square Kilometre Array (SKA) project.
The purpose of this DDR is to review the AAVS1 design to ensure that the planned approach will produce an AAVS1 system that is representative of the performance of LFAA in SKA1 and be able to verify an identified list of LFAA requirements.
The main items to be reviewed by the international panel are:
- Proposed design of AAVS1
- Capability of the AAVS1 design to be compliant with the applicable specifications
- Development work and results to date
- Costing overview for AAVS1
- Risk register, top level
After a very fruitful meeting, the panel concluded that: AAVS1 is a good platform to test maturity for the LFAA CDR.
Obviously the panel also provided us with useful recommendations, such as prioritizing outcomes and focus on the schedule. Besides this the panel encouraged us to use nearby (Europe) test-facilities, as we currently do.
© V. JelicRecent observations with LOFAR revealed a bewildering variety of structures in polarization in several fields at high Galactic latitudes. The most interesting features are seen in the 3C196 field, a primary window of the LOFAR-Epoch of Reionization project.
A colour composite image of polarized radio emission observed in 3C196 field is shown in figure. Different colours represent emission detected at different Faraday depths. Straight and long filamentary structures are visible parallel to the Galactic plane. They are located somewhere within the Local Bubble. A system of linear depolarization canals (black stripes) is also conspicuous in the image.
A follow up analysis of this data showed a surprising, yet clear, correlation between the filamentary structures detected with LOFAR and the magnetic field orientation, probed by the Planck dust polarization maps (Zaroubi et al. 2015). This finding points to a common, yet unclear, physical origin in this specific area in the sky. A filamentary structure is aligned with the magnetic field of our Galaxy and probably consists of both gas and dust. This calls for further multi-frequency analysis and observations of a much larger area around this field.
© JIVEFor the last few years, the standard observation bandwidth of the European VLBI Network has been 1 Gbit/s. Work has been ongoing to upgrade this bandwidth to improve the sensitivity of the array. Recently the first 2 Gbit/s user experiment has been observed. This experiment was recorded on disk for later correlation here at JIVE, but we're also working hard on making this bandwidth available for e-VLBI.
As part of this effort we did our first "live" e-VLBI test at this doubled data-rate with participation of telescopes from Sweden (Onsala), Germany (Effelsberg), Italy (Medicina), Spain (Yebes) and South-Africa (Hartebeesthoek).
In order to achieve this the DBBC digital backend is connected to a piece of equipment called FILA10G developed by Gino Tuccari and his groups at MPIfR (Germany) and INAF (Italy). This FILA10G hardware reformats and packetizes the data and sends it out over its 10GbE network interface directly onto the Internet to JIVE. There the data is fed into the SFXC software correlator, which runs on a 400-core computer cluster which processes the data in real-time. Results are available immediately as shown by the "fringes" in today's image that indicate that we indeed detected the observed source.
JIVE would like to thank everybody involved in this test.
© Tullia SbarratoNote that the Colloquium starts at 16:00 in the auditorium today!
The existence of extremely massive black holes at very high redshift is a true challenge to the commonly accepted black hole formation and evolution models. The quasars found at z>4 host extremely massive black holes, up to the extreme case of a quasar found at z>6 with 11 billion solar masses.
These objects are particularly problematic: there is not enough time to accrete such large masses in a standard scenario. The presence of a jet could speed up the accretion process enough to build up 10^9Msun black holes before z~6 from a reasonable black hole seed. Studying the population of jetted quasars is hence necessary.
The peculiar orientation of blazars (that have jets directed along our line of sight) makes them the most effective tracers of the whole population of jetted quasars. Do relativistic jets really have a role in the early formation of extremely massive black holes? Does the high-z quasar population have a different fraction of jetted sources? It seems so, and this can help us drawing strong conclusions about the most urgent question: how could the first, most massive black holes form so fast in the early Universe?
© Photos: The Dirkx family and L. GurvitsOn 22 October 2015, the Delft University of Technology offered the stage of its Aula to Dominic Dirkx of the Space Science and Innovative Applications Group of JIVE. The reason was both charged and pleasant: the defence of his PhD thesis Interplanetary Laser Ranging. Dominic worked on this challenging topic for the past four years, under the auspices of the EC FP7 project ESPaCE.
Laser ranging is a promising technique which addresses the need for ever more precise determination of the spacecraft state vector, i.e. its position and velocity etc within the Solar system. In order to meet the requirements of prospective planetary science missions, Dominic has developed novel relativistic approaches for describing the laser light propagation over interplanetary distances, and its handling at an Earth-based station and on-board a spacecraft. The methods developed in the thesis are directly applicable to planetary missions like the ESA's Jupiter Icy Satellite Explorer (JUICE), scheduled for launch in 2022.
One might wonder about the communality between the topic of Dominic's thesis and VLBI, the core business of JIVE. The thesis has proved the intuitive feeling that there is a substantial overlap in the interpretation of measurements by laser ranging and by VLBI tracking of deep-space probes. Moreover, both techniques are highly synergistic in addressing a broad variety of science areas. Planetary science missions of the coming decades will exploit both laser ranging and VLBI tracking, implemented as Planetary Radio Interferometry and Doppler Experiment (PRIDE).
The committee was impressed by Dominic's work, and duly awarded a Doctoral degree with the distinction cum laude. Well done Dominic, congratulations!
© ASTRON, 2015The hard work on the APERTIF correlator is paying off - on 8 October 2015, the first real-life fringe was measured on a celestial radio source, using two WSRT dishes! This is not only a great success from a technical perspective, but it also showed that such a complex system can be delivered on time.
In the weeks before reaching this milestone, the firmware (DESP) and commissioning teams cooperated seamlessly. The new correlator module was installed on a UniBoard FPGA, and step by step the optical fibers, new DDR3 memory, beamformer modules and receiver chains were included. This systematic approach allowed us to find (and squash) any bugs in an early stage.
The inset on the top right shows the installation of new DDR3 memory at a beamformer. This memory is used for the transpose operation (see daily image 19-05-2015). The data stream is then transmitted to the correlator by means of optical fibers. The bottom right inset shows the optical fiber interface on a correlator UniBoard.
The actual fringe is shown in the bottom left graph. It is measured using a single 12.207 kHz channel at 1.498 GHz. Two WSRT dishes on a 288 m East-West baseline were pointed at 3C147 for a period of 300 seconds, without any delay tracking. Also shown is a measurement towards the zenith, away from any strong source, where the correlation should be negligible, or rather noise-like. The measured variance of the correlation coefficient is indeed as expected.
© ASTRONArchitecture is the art of translating ideas in the heads of people into a detailed model of a structure, which can then be realized in the real world. As in building and in electronic hardware, also in software architecture is a necessary step, especially when large complicated systems need to be set up in a consistent and well-defined manner. Without a decent architecture, our software ''buildings'' will not be robust, scalable, extensible or whatever other property is necessary for the system. Still, software architecture is a relatively young art, starting to be properly formulated only in the 1990's, and therefore it has much less historical knowledge and practices to build upon.
To learn the process of creating a decent architecture, a four-day course was organized at ASTRON between 21 and 24 September 2015. The course, given by Dana Bredemeyer of Bredemeyer Consulting, was attended by a small group of ASTRON people from the R&D and RO departments, and by people from external parties such as ASML, TomTom, Elekta, NXP and the eScience Centre. This made an interesting mix of knowledge, experiences, and backgrounds that became clearly visible during the many exercises that were thrown at us during the course. The growing amount of paper hanging on the wall is a clear demonstration of the enthusiasm with which these exercises were conducted.
In the breaks, the opportunity was taken to show some of ASTRON's highlights to our visitors and make nice walks through the woods and along the moor. Our visitors were highly impressed by ASTRONs technical skills and our unique location.
© ASTRONLast weekend we received the sad news of the death of Prof. Rod Davies CBE, FRS. Rod was emeritus Professor of Radio Astronomy at the University of Manchester. He was previously the Director of Jodrell Bank (1988-1997), and chaired the European VLBI Network (EVN) Consortium Board of Directors (CBD) in the early 1990's. He was also one of the original board members that established the JIVE foundation in 1992.
I first met Rod Davies when, as a graduate student, I attended his course on radio astronomy receiver systems. I got to know him better when I was occasionally drafted in to support him during his reign as chair of the EVN CBD. I also had the opportunity of working alongside him in the Manchester physics labs in the mid-1990s. The first thing that struck me about Rod was he was a real gentleman - lightly spoken but very clear and precise in what he said. I remember being very impressed how easily he could shift between his role as director of a major observatory with all the pressures that went along with that, and his role as university teacher and student mentor. It was in the labs that I learned most from Rod - his understanding of basic physics was profound, and he saved my bacon on many occassions as I and the students struggled to get some vintage equipment to produce the "right" results - I think he was the only person that really understood what the notorious micro-strip experiment was supposed to achieve! While Rod was always polite and measured, he could also make his point strongly when he wanted to - I remember well being gently rebuked in his polite understated way for spending just a bit too long at lunch with the students one day.
Rod was the driving force behind Manchester's first steps towards being a major force in the study of the Cosmic Microwave Background (CMB). Many were openly scpetical of this effort when the first high-frequency Dicke-switched horns appeared outside the Jodrell Bank Dev(elopment) Labs in the mid-1980s, and there were plenty of jokes about what these systems might (or might not) be detecting. However, once these experiments were transferred to the much dryer and sunnier climes of mount Teide in Tenerife, the performance of the system was transformed. Rod and his team (now including the IAC as local collaborators in Tenerife) were first able to set new limits on the isotropy of the CMB and later detected the tiny fluctuations of temperature on angular scales of 5-8 degrees. Later measurements, together with other ground and space based observations, formed the foundation of a new era of precision cosmology. With this fantastic track-record established, it was natural for Manchester, under Rod's leadership, to make major scientific and technical contributions to the ESA Planck CMB mission, in particular developing the space-qualified 30 and 44 GHz receiver systems. Rod was active in the analysis and interpretation of Planck data right up until his death.
In recent times, I was lucky enough to bump into Rod in the Alan Turing building in Manchester occasionally, and I could quiz him on the latest Planck results and in particular what the latest idea was about the anomalous radio emission that had been discovered as a new and unexpected component of the radio (galactic) foreground. Rod was also very interested to hear what was happening here in Dwingeloo at both ASTRON and JIVE.
Rod's death represents a major loss to our field but his contribution, and the graceful style in which it was delivered, lives on in the many students and colleagues that Rod inspired across the world. He will be sorely missed.
© Huib IntemaOne of the relatively unexplored areas of astronomy is the sub-GHz radio sky at sub-arcminute resolution. The wide fields-of-view of current and future low-frequency radio interferometers (LOFAR, MWA, JVLA, GMRT, SKA-low) make them potentially powerful survey instruments, yet it comes at the cost of significantly increased complexity in the data processing.
One major hurdle is to properly account for the direction-dependent distortions in the presence of large numbers of detectable cosmic sources within the field-of-view and beyond. One essential ingredient is having an accurate reference model of the sky at a similar frequency and resolution.
In this talk I will present methods and results of the fully automated processing of the 37,000 deg^2 archival 150 MHz GMRT sky survey (TGSS) data using the SPAM package. Covering about 90 percent of the radio sky, this ~25'' survey provides an excellent reference catalog for LOFAR and MWA, as well as a unique view on the relatively unexplored southern hemisphere sky, opening up many options to search for interesting objects.
© ASTRONKIC8462852 (Boyajian et al. 2015 - http://arxiv.org/abs/1509.03622 ) has created quite some excitement as perhaps the first example of an alien megastructure eclipsing what appears to be a fairly normal, main sequence star. In particular, Wright et al. (see: http://arxiv.org/pdf/1510.04606.pdf) have suggested that the light curve is consistent with a Dyson swarm (see image above left for my poor attempt at how that might look "op afstand" (at a distance) and also https://en.wikipedia.org/wiki/Dyson_sphere). Other more conventional but also somewhat contrived explanations have their roots in disrupted cometary/planetary systems.
For the Dyson swarm scenario, the remarkable depth of the obscuration in the light curves of KIC8462852 (dips in stellar luminosity exceeding 20% are observed) suggests a scale of astro-engineering that is best associated with something approaching a Kardashev Type II civilisation (see https://en.wikipedia.org/wiki/Kardashev_scale ) - in other words, a civilisation with energy requirements of order 400E24 Watts or 400 YW (yottawatt) - i.e. around 14 orders of magnitude greater than the current total energy consumption of our own species on planet Earth).
If one assumes that advanced Type II civilisations use radio waves to communicate across their planetary system (and why wouldn't they...) one can ask the question about what level of broadband radio emission we might expect from such a civilisation. My best estimate of the global (waste/leakage) radio emission from our own Kardashev Type 0.7 civilisation (note it's a logarithmic scale...) is of order 50 MW (EIRP) at frequencies
In this back-of-an-envelope analysis, I make a key assumption that the waste radio emission generated by a communicating civilisation scales linearly with its total energy budget, and this then predicts a total isotropic waste radio emission output from a Type II civilisation associated with KIC8462852 of ~ 50E20 Watts or 2.5E12 Watts/Hz (10-2000 MHz). Since KIC8462852 is located at a distance of ~450 pc or ~1.4E19 metres, this output translates to a flux density of 0.1 Jansky, a level of output that is readily detectable by most radio telescopes today with integration times of only a few seconds. Note that as a main-sequence star, any natural emission from KIC8462852 is essentially undetectable at these sensitivity levels.
Somewhat disappointingly, radio surveys (e.g. NVSS and WENSS) detect no radio emission at the position of KIC8462852 although admittedly these represent very shallow observations (see images above - the WSRT WENNS 326 MHz image [centre], and the VLA NVSS 1400 MHz image [right] - the green cross hairs indicate the position of the KIC8462852. NVSS reaches 1-sigma r.m.s. noise levels better than 0.0025 Jy i.e. about 40 times better than the 0.1 Jy emission that we might predict from KIC8462852. With a resolution of 45 arcseconds, NVSS is unlikely to resolve any braodband radio emission associated with KIC8462852, even if this is distributed on scales associated with a highly capable space-faring civilisation active within an extended, colonised planetary system. Naturally, any conclusions based on this analysis depend crucially on the validity of these somewhat arbitrary assumptions - much deeper integrations by the JVLA and LOFAR are highly desirable in order to place even better limits (x1000) on any broadband radio emission associated with this system. A relatively shallow but very broadband observation by the Allen Telescope Array (see http://arxiv.org/abs/1511.01606, appearing after this AJDI was submitted) arrives at a similar conclusion suggested by the existing shallow radio surveys described here.
Finally, it should be noted that the full SKA and other next generation telescopes such as the NG VLA will go 50-100x deeper than current facilities, permitting interesting limits to be placed on nearby stellar systems within a few hundred light years from the Sun.
© NOVAThis period of the year, every now and then a fairly bright meteor can be seen. The chance is big that these belong to the Taurid complex, a meteor shower peaking early November and active for over 2 months. Taurids originate from comet 2P/Encke.
Since summer this year, on the roof of the ASTRON building, a dedicated All-sky fireball patrol camera is operational, monitoring the sky in high resolution every night. It was bingo the 11th of October, when the first bright fireball was registered, rather surprisingly being a very early Taurid. The fireball was also seen by other stations, from which could be deduced that the meteor appeared west of Denmark above the North Sea.
Although of cometary origin, Taurid meteoroids can be of pretty large size, and can penetrate deep into earth's atmosphere. They are slow, have higher tensile strength than other cometary meteors, and if cometary meteor showers are able to drop meteorites, the Taurids are the biggest candidate. In 2005, a telescopic lunar impact was observed, and traced back to the Taurid complex.
This year, several extremely bright Taurids were witnessed around the world, including Poland and Bangkok. This picture shows the 11th October fireball, amid the beautiful dark Dwingeloo sky. The breaks in the trail are the result of an alternating chopper, used for precise measurement of the velocity.
© Madroon Community Consultants (MCC)Henk (1921) en Willy (1926) Sieders took care of the Dwingeloo observatory for 15 years, between 1969 and 1984. During that time, the institute expanded from a single 25m dish to a row of 14, and staff quintupled to more than a hundred.
Henk looked after the buildings and the grounds, and drove people and things around as far as Leiden and Bonn. If necessary, he also built buildings and furniture.
Willy looked after the guest-house and mothered the guests, ranging from thin student-observers to the Great and the Good (some of them very). On one occasion in 1980, she cooked for the entire Foreign Advisors Committee plus an attentive Management Team.
Despite the usual ailments they are still going strong, happily living together in Hoogeveen. As the picture shows, they remain keenly interested in the ASTRON family, and a discussion with them quickly becomes an enjoyable jaunt down memory lane. Henk is a wizard with computers, while Willy makes highly intricate figurines from impossibly tiny beads.
They do not leave home very much nowadays, but if you would like to visit them (De Maaier 71) to talk about this, that and the other, you are very welcome. But you should call first (0528-230090), and not too early in the day.
© NTRTonight (wednesday 25 nov) airs the last episode of the Klokhuis Heelal series that was recorded in part at the Westerbork Synthesis Radio Telescope (WSRT). The size of the audience has been excellent; e.g. episode 2, on the outer planets (image above) drew 380.000 viewers -- the Klokhuis team is very excited about this success.
How were these series realized? Above you can see the various stages for a single scene of episode 2, our fly-by of Saturn's moon Titan. It all starts with an idea from the director, Yvonne Smits. She and her producers and editors pitch it to the TV network.
So the next time you watch a SuperHero movie, you know how it is done.
© Rob van der Meer, Ronald HalfwerkOn Saturday 3 October 2015 the station contract between the International LOFAR Telescope Foundation (ILT) and the three new Polish stations was signed in a special(dedicated) ceremony at the University of Warmia and Mazury in Olsztyn, Poland (UWM). During the two hour meeting, which was followed by a tasty light lunch buffet, there were several presentations on the reason for this meeting and about the road towards this meeting. Prof. Katarzyna Otmianowska-Mazur and Prof. Andrzej Krankowski opened the meeting by introducing all the guests, including:
The last presentation before the actual signing was necessary because of the legal construction around POLFAR, POLFARO, UWM and ILT. Most people in the audience would never see the contract, so the agreement was shortly explained:
Following the explanation, the Rector Magnificus of the University of Warmia and Mazury in Olsztyn, Prof. Ryszard Gorecki (right) and the director of the International LOFAR Telescop (ILT), Dr Rene Vermeulen (left), signed the contract and showed the signed contracts to the guests and the press.
More information on the three LOFAR stations in Poland and ILT is in the press release sent out when the contract for construction of the three Polish stations was signed in June 2014.
This video from the Olsztyn TV shows the signing event and background information.
© Lorant Sjouwerman (NRAO)The "Bulge Asymmetries and Dynamic Evolution" (BAaDE) project aims to significantly improve our knowledge about the dynamical content and evolution of the Galactic Bulge. The project is designed to detect thousands of line-of-sight velocities of evolved stars, which are likely to show SiO maser emission when selected on infrared color. Statistically, this sample will complement optical and near-infrared surveys that are performed at higher Galactic latitudes to reduce bias due to extinction, and outweigh the available data at the low latitudes in the Galactic Plane where dynamical and evolutionary features are most prominent and not blurred by off-plane effects. Follow-up observations in the infrared and with connected and very long baseline interferometers of individual sources will yield stellar and circumstellar shell properties, parallax distances and proper motions, and provide consistency checks with the BeSSeL and GAIA surveys.
Here I will briefly describe the motivation for the project, the preparations performed in the last few years, the current status, and the work to be performed in the next few years. Topics to be included are previous work on maser stars, an infrared color selection to maximize the SiO maser detection rate, Carbon-rich star pollution of the sample, a particular calibration method which had to be adopted due to the lack of calibrators and to reduce calibration overhead, as well as the special data reduction tricks to go with this calibration. I will show some of the data samples that we are obtaining, and touch on remaining challenges.
The IRAS color-color diagram (upper right; Van der Veen & Habing, 1988) plays an important role in the selection of SiO maser targets but unfortunately cannot be used in the Galactic Bulge to benefit the BAaDE project. Using a judicious selection in MSX colors instead (shown by the diagram) we manage to obtain a detection rate of over 70%, which provides the key to the success of this project.