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

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  • 05/06/14--17:00: The Scintillating Crab
  • © Richard Fallows

    The Crab Nebula is a supernova remnant, and a strong radio source, which contains at its heart a pulsar which was amongst the first discovered, in 1968. As a compact source, it is known to scintillate ("twinkle") as the radio signal is scattered by density variations in (any of) the interstellar medium, the Sun's atmosphere (solar wind) and the Earth ionosphere. This is exactly the same effect as can be seen when stars twinkle due to density variations in the Earth's atmosphere and can be recorded as a rapid variation in the power received. The interstellar medium is also known to disperse the radio signals from pulsars making the lower frequencies of each pulse arrive later than the higher ones.

    This image is a dynamic spectrum of one minute of data from an observation of the Crab Nebula taken using the high-band antennas (HBA) of the coherently-added LOFAR core stations. The curved lines are bright pulses from the pulsar, dispersed by the interstellar medium. Two bright pulses are seen in this image, with many(*) fainter ones in between.

    Superposed are faint vertical stripes which are successive maxima in the total radio power received from the Crab, corresponding to scintillation due to the solar wind. These maxima occur simultaneously across the frequency band displayed here, indicating that the scintillation can be considered to be "weak", ie, the scintillation pattern seen is built up from interference between only the scattered waves and an unscattered component. The scintillation can be seen to increase in strength towards lower frequencies.

    (*) The Crab pulsar has a rotation period of 33 milliseconds, so there are about 30 pulses a second, i.e. about 1800 in the minute shown here. The reason that some pulses are much brighter than others is partly intrinsic to the pulsar, and partly interstellar scintillation.


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    © Tim de Zeeuw

    ESO is an intergovernmental organization for astronomy founded in 1962 by five countries. It currently has 14 Member States in Europe with Brazil poised to join as soon as the Accession Agreement has been ratified. Together these countries represent approximately 30 percent of the world’s astronomers. ESO operates optical/infrared observatories on La Silla and Paranal in Chile, partners in the sub-millimeter radio observatories APEX and ALMA on Chajnantor and has started construction of the Extremely Large Telescope on Armazones.

    La Silla hosts experiments, robotic and national telescopes as well as the NTT and the venerable 3.6m telescope. The former had a key role in the discovery of the accelerating expansion of the Universe and the latter hosts the ultra-stable spectrograph HARPS which is responsible for the discovery of nearly two-thirds of all confirmed exoplanets with masses below that of Neptune. On Paranal the four 8.2m units of the Very Large Telescope, the Interferometer and the survey telescopes VISTA and VST together constitute an integrated system which supports 16 powerful facility instruments, including adaptive-optics-assisted imagers and integral-field spectrographs, with half a dozen more on the way and the Extremely Large Telescope with its suite of instruments to be added in about ten years time. Scientific highlights include the characterisation of the supermassive black hole in the Galactic Centre, the first image of an exoplanet, studies of gamma-ray bursts enabled by the Rapid Response Mode and milliarcsec imaging of evolved stars and active galactic nuclei. The single dish APEX antenna, equipped with spectrometers and wide-field cameras, contributes strongly to the study of high-redshift galaxies and of star- and planet-formation. Early Science results obtained with the ALMA interferometer already demonstrate its tremendous potential for observations of the cold Universe.

    The talk will outline the development of ESO, summarize the current program and consider new opportunities for the coming decades.


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    © NL SKA Office

    The week of SKA meetings (mostly related to aperture arrays) in early April was concluded by a site visit to ASTRON's observatories. The group was joined by Monique Sluiman, our new management assistant (2nd from left).

    We started in Westerbork where all were impressed at the sight of the array of 25m WSRT dishes. The secrets of the EMBRACE aperture array were revealed by Andre Gunst and Ilse van Bemmel, who flung open the doors of its dome.

    After a quick cup of coffee, the trip was continued to LOFAR, where a visit to the Superterp allowed people to see the LBA and HBA antennas for real.


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    © Rob Millenaar

    My connection with the IAR goes back to 2005 when Bou Schipper and I visited the country to carry out the RFI monitoring campaign for their SKA site bid at the time.

    The IAR is the home for the radio astronomy activities in Argentina. I recently passed through their offices on my way to Chile, and met with Marcelo Arnal, its director, and some of the engineers. I updated them on the current state of the SKA project, its schedule and future. We also discussed the developments in spectrum monitoring. In return I was updated on the projects that IAR is involved in. Examples are:

  • TIGO: The Transportable Integrated Geodesic Observatory, which aims to build modular transportable VLBI stations, integrated with satellite laser rangers, to fill in gaps in coverage in the Southern Hemisphere. The project is a joint Chilean/German affair, but the IAR is involved as well. More information here: http://www.tigo.cl/index.php?lang=en

  • LLAMA: The Long Latin American Millimeter Array, which ultimately aims to build a mm VLBI network, joining ALMA, APEX and/or ASTE and a new 12m millimeter radio telescope to be located at a high elevation site in Argentina. The first goal is to build that new telescope. Check their website, here: http://www.iar.unlp.edu.ar/llama-web/english.html

  • Aquarius: IAR was involved in the development of instrumentation for the Aquarius Earth observation satellite, which was launched by NASA in June 2011. Website here: http://aquarius.nasa.gov

    The photo shows a collage of impressions of the IAR facility in Villa Eliza, near La Plata. The upper left panel shows the twin 30 meter radio telescopes that are now retired, until funds are found to revive and rescue them, just as was done for the Dwingeloo telescope. The upper right and lower left panels show the control panels that once set the telescopes in motion. The top middle panel shows an interesting remnant of the past: the META II supercomputer, which was dedicated to SETI searches. This was a quite famous specialised beast, developed by Harvard in the late eighties. In the early nineties one of the 30 meter telescopes was used to do a southern hemisphere survey at 21 cm with a spectral resolution of 0.05Hz. The mid-bottom panel shows IAR's anechoic chamber, which is used for antenna measurements. It is quite large: about 12x6x6 meters.

    No visit to the La Plata region would be complete without a visit to the old Gautier optical telescope in the downtown observatory, see the panel lower right. A 43.3 cm telescope, with a whopping 9.7 meter focal length, the telescope was built in 1894, and is still in good working condition.


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    © ASTRON

    On several ASTRON boards, a PIC-controller is used to control the hardware. Other options would be to use a Raspberry Pi or an FPGA. The advantages of the chosen PIC microprocessor are:

  • Integrated Ethernet, hence low(er) self-generated RFI.

  • Real-time operating, (No OS interrupts).

  • Lots of I/O ports, as well as multiple integrated A/D converters.

  • Flash programmable. Also possibility to remotely program over ethernet or do a Firmware update over ethernet.

    The image shows the APERTIF LO-Generator (LOG) control board using this microcontroller. The board generates 2 independent SPI busses as well as 4 independent I2C busses. Multiple general purpose I/O pins are connected to the backplane. All connections to the backplane are made by means of isolated buffers to protect for failures and electrostatic discharges (ESD). Finally, for status signals and demonstraton purposes, the front-panel has six multi-color LEDs.

    The software to communicate with the control board makes use of a client/server model. The server software takes care of parsing through the commands to generate the I2C and SPI signals.


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    © Gemma Janssen

    The re-opening of the Dwingeloo Telescope by Nobel prize winner Joseph Taylor had an added bonus for the ASTRON pulsar group. As prof. Taylors work is inspiring to all of us, we invited him to a lunch at The Bospub(*) to get to know each other, and to discuss past, present and future pulsar work.

    The group was treated to excellent stories by prof. Taylor and our visitor Dan Stinebring about disk space data-tape restrictions, coherent dedispersion of the very first millisecond binary pulsar observation, and early Arecibo pulsar observing.

    We had nice conversations on local recent results like the new pulsar discoveries by the LOTAAS survey and the state-transitioning missing link pulsar J1023+0038. Also, the latest techniques in radio (amateur) astronomy were discussed, as well as the prospects of directly detecting gravitational waves with pulsars in the (hopefully) near future.

    (*) The Bospub (public house in the woods) is an idyllic establishment in the woods near the Dwingeloo observatory.


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    © B. Fiorelli

    The SKA Low Frequency Aperture Array will consist of large arrays of antennas. Each station, as we call them, will be populated by 256 antennas, covering an area with a diameter of 35m. Measuring and testing such an instrument is a challenging task that involves a high level of complexity. In this context, a large part of the design effort relies on simulations.

    The (irregular) LFAA array configuration is specified to be dense at the low end of the operational bandwidth. It requires a full-wave approach to be properly represented, including the effect of mutual coupling between antennas. In recent years, as a result of increasing computational capability and the development of fast algorithms, most of the available commercial codes are becoming capable of simulating very large structures. That given, controlling and understanding the EM behaviour of large irregular arrays with a high level of reliability is not straightforward. Validation of the simulation work is essential and represents a big challenge when facing the issue of characterization.

    Due to the size of the antenna at the bandwidth of interest (50-450 MHz) for LFAA, the most accessible and repeatable method is to perform array measurements in the near-field region. With this approach, some measurements have been performed in Cambridge on a small dense regular array (see image).

    The measurement concept is relatively simple, but the realization brings in a lot of uncertainties. It is worth noticing that, in spite of the windy and rainy weather during the measurement campaign, we achieved very good match of measurements with simulations, proving the reliability of our simulations in a dense array context.

    Detailed results have been presented at EuCAP 2014 in April.


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    © Eric Clausen-Brown (MPIfR)

    Black hole accretion disk models typically assume that the magnetic field pressure is much less than the plasma pressure. However, simulations that include an abundance of poloidal magnetic flux threading the disk find that this flux is transported inwards until the magnetic pressure reaches an equilibrium with the ram pressure of the accreting plasma. At this point a "magnetically arrested disk" is formed where the magnetic pressure is well above the plasma pressure. The resulting equilibrium magnetic flux threading the hole then remains somewhat steady, and is proportional to the product of black hole mass with the square root of the accretion rate.

    We test this magnetically arrested disk scenario in a sample of radio-loud blazars and radio galaxies, and find a good agreement between the accretion rate of these sources and the poloidal magnetic flux threading their central black holes. The accretion rate and black hole magnetic flux for a given source are determined by the inferred accretion luminosity and the VLBI coreshift effect, respectively.

    We have also conducted a similar analysis for two jetted XRBs and for the galactic center, with encouraging results. The implications of our work with regard to jet power and the radio loud/quiet dichotomy will be discussed.


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    © Adriaan Renting/Ilse van Bemmel/Harm-Jan Stiepel

    On April 24th ASTRON, JIVE, NOVA and CAMRAS organised the annual Girl's Day. The main purpose of this event is to immerse girls in their early teens in science and technology related professions. Every year girls leave with a more positive image of the work done here, and get a better idea how science and technology change the world around them. This may well stimulate them to choose a more technical career path for themselves.

    This year 24 girls visited, had lots of fun during the lectures and hands-on workshops. Split up in smaller groups they attended two 20-minute talks, and four workshops of 45 minutes each, which are organised in two blocks of 1 lecture and 2 workshops with lunch break in between. The day was concluded with a quiz for the full group, where we tested their knowledge of science and engineering.

    The two lectures cover the basic principles of radio astronomy, given by Ilse van Bemmel, and engineering, given by our own Engineer Powerwoman Gabby Aitink-Kroes. The four workshops had the following themes:

    Chatting with Astronomers: The girls use text chat to talk with a female Astronomer, and draw a picture of what they learn about her. The goal is for them to learn what the life of a scientist looks like. Roy Smits will show the results of these in a separate Daily Image.

    Programming with Minecraft: We use the mod ComputerCraft for the popular computer game Minecraft to have the girls control and program a small robot in the game. This workshop was new this year, but a whopping success once everyone got the feel for it. Some of the teams got a real taste of what it means to be a programmer and had a lot of fun.

    CAMRAS volunteers showed the girls the Dwingeloo Telescope, explained what a pulsar is, and then had the telescope track a live pulsar for the girls to listen to. Afterwards they did an experiment demonstrating the Doppler effect using a tennis ball on a rope with a small beeping speaker in it.

    Soldering: The girls are taught how to use a soldering iron and how to put different components on a circuit board. With this they then constructed a small device with blinking LEDs that would show the words LOFAR and ASTRON if you wave it around. Initially the girls usually react negatively when we tell them about the workshop, but at the end of the day for most of them it's the most enjoyed part of the event.

    As in previous years, we asked the girls and their accompanying teachers for their feedback. Overall we can conclude that this day was a big success! Everyone involved had lots of fun talking about their jobs and explaining to the girls what working here is like. But most importantly, we managed to impress 24 young girls that science and technology is tons of fun!

    The annual Girl's Day is part of a European initiative to promote girls to choose a career in Science and Engineering. In the Netherlands the Girl's Day initiatives are coordinated by VHTO. In the Netherlands 300 organisations and 9000 girls take part, while in the rest of Europe several hundred thousand girls visit over ten thousand locations.

    The animation above shows an impression of the events during the day. For a full list of all the pictures taken during the day, visit: All Girl's Day Pictures


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  • 05/18/14--17:00: Girlsday Drawings
  • © ASTRON + Girlsday-Girls 2014

    As every year, ASTRON has participated in the yearly Girlsday. Today we present the wonderful artwork that the Girlsday-Girls have produced at ASTRON during live chat-session with females astronomers.

    The chat session involved chatting (via Skype) with a professional female astronomer. All questions were allowed; from work to hobbies to even more personal details. Part of the assignment was to draw their findings onto an A3-paper. Working in pairs, they produced some magnificent artwork showing the astronomer, her work and many aspects of her personal life. This exercise connects the image of a female astronomer to the personal world of the students.

    Many thanks to all the Girlsday-Girls, and the female astronomers who volunteered to answer all the girl's questions, to make this event so very successful! All drawings have been sent to the relevant astronomer as a reminder of this event.

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


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  • 06/01/14--17:00: A-MKID warm mirrors for SRON
  • © Johan Pragt

    The NOVA-ASTRON team recently produced 2 mirrors for the A-MKID test setup of SRON. These mirrors are called warm as they are applied at the room temperature part of the test setup, in contrast with the cold mirrors produced in 2013 (by the same team) that are applied at about zero Kelvin.

    Within two weeks from the request for production, two large accurate off-axis mirrors were delivered. Such a feat is only feasible with highly skilled personnel (Menno Schuil and Niels Tromp) and with the help of good equipment (Hermle 5-axis CNC milling machine) and short management lines.

    A-MKID (APEX-Microwave Kinetic Inductance Detectors) is a development at our sister institute SRON and others. The A-MKID is a dual-band camera, simultaneously covering two atmospheric windows centered on 350 GHz and 850 GHz. A-MKID is for APEX (situated in Chile) what is Apertif for the WSRT: it offers (many) more pixels to the telescope. With in total about 25000 pixels, the A-MKID instrument will be the largest submillimeter-wave camera on any telescope ever.

    http://www.sron.nl/kinetic-inductance-detectors-research-and-technology-2506


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    © MSSS / ASTRON

    The Multifrequency Snapshot Sky Survey (MSSS) is LOFAR's first large-scale imaging survey, and has played a large role in focusing LOFAR development efforts. Since early 2013, the emphasis has been on the HBA portion of MSSS (spanning the 120-160 MHz range). This has led to manyniceimages, and is also being used for a broad range of early science projects (such as those presented in the MSSS portion of the LOFAR Science Workshops). As expected, the HBA portion of MSSS has allowed rapid output from the observations!

    We are happy to announce that the final MSSS-HBA observations have recently been completed!! The 3616th field was observed during the weekend of 9-10 May 2014, meaning that images have now been made of the entire Northern sky using LOFAR. This massive achievement puts the cap on a huge effort undertaken by the LOFAR Science Support group, and in particular Michiel Brentjens and Emanuela Orrù, who have both spent a great deal of time in setting up the observations and the corresponding pipeline processing. Particularly in the early days of the survey timeline, these were by no means trivial tasks, and their work has paved the way for making normal LOFAR imaging observations possible. It is also important to acknowledge the essential contributions of the rest of the Science Support team (Carmen, Richard, Wilfred, and their fearless leader Roberto!) and Antonis. Finally, none of this would have been possible without the hard work of the Software Group, whose contribution often goes quietly unremarked but is absolutely essential for us lucky astronomers to have a good time studying LOFAR images.

    To celebrate this milestone achievement, we'll celebrate today at ASTRON with some tasty cake during our coffee break. I wonder who will have to light the 3616 candles...


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    © NASA/GSFC

    Gamma-ray bursts are a broadband phenomenon, with emission detected across the electromagnetic spectrum from low-frequency radio waves to high-energy gamma-rays. Besides this extremely broad spectral range, they are also observed over a very large range of timescales, from millisecond variability in gamma-rays to the afterglows at radio frequencies that can sometimes be observed for years after the initial gamma-ray trigger. Our current understanding of gamma-ray bursts is based on these multi-frequency and multi-timescale observations.

    In this talk I will show how information from the various spectral regimes has led to a broadband picture of the physics behind the observed emission, the progenitors, and their environment. I will highlight recent developments, both observationally and in modeling work, for instance the discovery of optical circular polarization, the detection of the brightest gamma-ray burst of the last three decades, the searches for early radio emission, and modeling observed light curves directly with state-of-the-art jet simulations.

    Finally, I will discuss how the possibilities that several new and upgraded radio observatories offer will lead to a better understanding of the macro- and microphysics behind these enigmatic phenomena.


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    © ASTRON

    In our series of daily images (18-12-2013 ,21-02-2014 and 21-03-2014) on the progress of the Low Noise Tile (LNT) project, today's image shows the measurement results for the Medium Size Tile (MST) inside THACO.

    The plot, top left, shows 2 lines, whereas the upper is the measurement result of the 2010 design, which uses discrete transistors including several lumped components.

    The lower line shows the measurement result of the MST, using an low noise amplifier module with integrated active bias, as the first amplifier stage.

    As one can see, we are able to get the noise temperature down by ~20%, which is very promising, as such an array noise temperature is in line with SKA sensitivity requirement!

    The MST is currently being shipped to Australia, where it will be used for comparative testing, next to the Australian ASKAP checkerboard array and the Canadian AFAD thick vivaldi array, during the Phased Array Feed Element Test Protocol by the SKA Dish Consortium at the Parkes telescope site, May - June 2014. Goal of this measurement campaign is to benchmark the candidate Feed Array/LNA technologies for use in the SKA1-survey PAF systems.

    The front end module design shown, is limited in frequency range down to 1000 MHz, as it holds GSM band filtering. Future work will continue investigating the design possibilities down to 500 MHz, the lower frequency limit of the MFAA system.


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  • 05/22/14--17:00: Tribute to Wubbo Ockels
  • © Nico Vermaas

    As a 14 year old boy I had to make a choice about the direction of my education. I dreamt of the stars and wanted to become an astronaut. So I decided to write a letter to Wubbo Ockels, our first Dutch astronaut, who was training for his shuttle mission at NASA in Huntsville, Alabama.

    To my utter surprise he not only received and read my letter, but he wrote back. A personal handwritten letter, encouraging me to choose an education in computer science, math, physics, biology. I took his advice and chose exactly that direction.

    I did not become an astronaut, but my dreams about the stars came true. Because I now work at the same Radio Observatory where I came to stare at the telescopes when I was that 14 year old boy. And Wubbo was one of the people who inspired and encouraged me at exactly the right moment.

    Wubbo passed away this week after a long illness, during which he showed and inspired us all how to make the best of a terrible situation.

    Thank you Wubbo Ockels, rest in peace.


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    © ASTRON

    At a ceremony held yesterday at the residence of the Italian Ambassador, the Head of the Astronomy Group of ASTRON, Prof. Raffaella Morganti, received a Presidential Decoration awarded to her by President Giorgio Napolitano, and presented to her by the Italian Ambassador Dr. Francesco Azzarello. Prof. Morganti was appointed Commendatore dell' Ordine della Stella d'Italia which translates to 'Commander in the Order of the Star of Italy', or 'Commandeur in de Orde van de Ster van Italie'. Knighthoods in the Ordine della Stella d'Italia are given to expatriates who have made an outstanding contribution to Italian prestige abroad. The Star of Italy is an old Italian identity symbol, it plays a similar role as 'de Nederlandse Leeuw'. It is the second Italian recognition Raffaella Morganti receives, after the Mondo Italia Award of last year.

    Raffaella Morganti has been Head of the Astronomy Group of ASTRON since 2007. In this period, the Astronomy Group has grown considerably and has become a very successful research group which plays a leading role in international radio astronomy. Thanks to the stimulating environment at ASTRON, Raffaella Morganti has been able, despite her duties as Head of the Astronomy Group, to remain successful in doing her own research, demonstrated by the fact she received a prestigious Advanced Research Grant from the European Research Council in 2012.


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    © UBC

    In the modern era of big data, many fields of astronomy are generating huge volumes, the analysis of which can sometimes be the limiting factor in research. Fortunately, powerful data-mining techniques have been developed by computer scientists, ready to be applied to various fields. In a recent paper, Wei Wei Zhu and Aaron Berndsen from the University of British Columbia plus collaborators present a novel artificial intelligence (AI) program that identifies pulsars from recent surveys using image pattern recognition with deep neural nets the PICS (Pulsar Image- based Classification System) AI.

    Traditionally, new pulsars are identified from diagnostic images by humans (such as the new pulsars found in the LOFAR pilot surveys). The AI mimics these human experts and distinguishes pulsars from noise and interference by looking for patterns from candidate plots. Different from other pulsar selection programs which searched for expected patterns, the PICS AI is taught the salient features of different pulsars from a set of human-labeled candidates through machine learning.

    The training candidates are collected from the Pulsar Arecibo L-band Feed Array Survey, which is carried out by a team including ASTRON's Jason Hessels and Joeri van Leeuwen. The information from each pulsar candidate is synthesized in four diagnostic plots, which consist of image data with up to thousands of pixels. The AI takes these data from each candidate as its input and uses thousands of such candidates to train its 9000 neurons. The deep neural networks in this AI system grant it superior ability in recognizing various types of pulsars as well as their harmonic signals.

    The performance of this system can be improved over time as more training data are accumulated. This AI system has been integrated into the PALFA survey pipeline and has discovered six new pulsars to date!


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    © NOVA Optical Infrared Instrumentation group

    After delivery of the first Cold Optics Bench (COB) of MATISSE in October last year, this spring also the second COB has been shipped to consortium partner MPIA (Max Planck Institute fuer Astronomie), where it currently undergoes the first tests. Both COBs are the Dutch contributions to MATISSE and have been designed and built by the NOVA Optical and Infrared Instrumentation Division at ASTRON.

    The delivery was celebrated at the Hannover Messe, held in April in Germany, and attended by both the Dutch secretary of state OC&W Sander Dekker, OCW Directeur Onderzoek en Wetenschap beleid Nora van der Wenden, NOVA director Wilfried Boland and NOVA chairman Paul Groot. A dozen industrial companies that contributed to MATISSE as well as a hundred visitors attended the ceremony. As part of the hand-over event, Felix Bettonvil (NOVA) and Frans Snik (U Leiden) highlighted two NOVA instrumental achievements, the first being the MATISSE work, the second iSPEX, a citizen science project aiming at measurements of aerosols with smartphones.

    On the upper picture, Dutch MATISSE project manager Felix Bettonvil on behalf of NOVA and Dr. Klaus Jaeger on behalf of MPIA sign the delivery document, with in the background also MATISSE lead engineer Gabby Kroes. The lower image shows the LM COB at MPIA on top of the cryostat base, shortly before closing the cryostat.

    MATISSE is an instrument designed for coherently combining the light of up to four telescopes of ESO's Very Large Telescope Interferometer (VLTI). By doing so, the VLTI and MATISSE emulate the aperture of a telescope with diameter of up to 200 m, resulting in a spatial resolution of up to 5 milli-arcsec in the L, M and N bands. Combined with a spectral resolution between 30 and 5000, it makes that MATISSE is well suited for the study of Young Stellar Objects, extra-solar planets and Active galactic nuclei, asymptotic giant branch stars and planetary nebulae.


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  • 06/05/14--17:00: Close-up of the Moon
  • © R. ter Horst

    Under a beautiful and quiet sky I took this image of the Moon in the evening of April 5 with a homemade 250 mm Schmidt Cassegrain telescope and an ASI120MM camera. About 2000 frames were stacked and processed with Autostakkert!2 and Photoshop to reveal all the details hidden in the video.

    The most prominent crater is Theophilus at the top, with the more flattened Mare Nectaris at the right of it. I wish we had more of these nights......


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  • 06/12/14--17:00: Dutch Camelopardalids
  • © Felix Bettonvil

    It has been predicted that, during the night of May 23/24 2014, a new meteor shower should appear. It would originate from the comet 209P/LINEAR, which was discovered in 2004.

    The new shower, named Camelopardalids, could, according to recent models, generate moderate activity of up to a few hundred meteors per hour. The latter did unfortunately not happen: not more than 10-15 meteors per hour were detected by observers in the favourably located US.

    For the Netherlands, maximum activity occurred during daytime, but the early morning of May 24 was clear enough to monitor any Camelopardalid activity. This resulted in this picture of one of the only three Dutch Camelopardalids detected. The picture was taken from Utrecht by Felix Bettonvil, with one of the CAMS network video camera's, and confirmed well before maximum that the stream exists.

    Every clear night, thirty sensitive CAMS cameras monitor the sky above the BeNeLux for meteor activity, resulting in 500+ orbits each month. The captured dust particle of 209P/LINEAR is visible as a trail in the upper left corner of the image, in the constellation of Cepheus. The inset shows the worldwide hourly counts, as derived from visual observers, peaking at 15/hour at maximum.


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