© SKA RSA / Richard Lord

On site however, things also evolved. An 20 by 20 meter area (indicated by the white arrow) has been cleared, to provide a suitable final destination for the prototypes.

The power needed to feed the electronics is provided via the Site Test Interferometer system, middle left side of the picture. This small white dish is monitoring the tropospheric stability.

During week 12 and 13, an ASTRON team will travel to the site and install the prototypes. Stay tuned for more beautiful pictures!

These environmental prototypes are part of the Array Prototypes work package of the

SKA Mid-Frequency Aperture Array consortium

This project is part-financed by the Northern Netherlands (SNN), the European Regional Development Fund, and the "Peaks in the Delta" program of the Dutch Ministry of Economic affairs, Agriculture and Innovation.

© Madroon Community Consultants (MCC)

The fact that David is a historian allows him to write a balanced history, in which for instance the role of the ingenieurs is given its proper place. He is particularly interested in the sociological processes that made astronomy so successful in the Netherlands(**).

(*) David is a historian, and is writing the book as a postdoc project for NWO. His PhD thesis about "Synthetic Thinking", written as a member of the Descartes Centre for the History and Philosophy of Science, was awarded the prestigious gold medal of the Teylers Foundation. It discusses the role of scientists and ingenieurs in the public debate in the first part of the 20th century.

(**) Apart from the manifest genius of Dutch astronomers, of course.

© ASTRON, 2014.

© Lister Staveley-Smith

© ASTRON

The other graph shows the results for the same 2x2 arrays, but now measured in the Compact Tile, a small test setup with 23 antenna elements. The picture shows the 1 m^2 tile with the Compact Tile in front. Besides the 4 center elements the Compact Tile is filled with elements of the previous design. Again the improvement of 10-15 K may be observed for the new LNT design.

The results as a function of frequency for the Compact Tile are better than for the larger 1 m^2 tile. This is caused by a lower contribution to the array noise temperature from noise coupling between the elements, in line with the better noise properties of the new design and the lower number of neighbor LNT elements. This is even more clearly visible in the Compact Tile results without surrounding elements, where these elements cannot contribute to the noise coupling. These results promise consistent array noise temperatures well below 40 K for the compact and larger arrays, when these arrays will be completely filled with the new LNT-modules.

These results promise consistent array noise temperatures well below 40 K for the compact and larger arrays, when these arrays will be completely filled with the new LNT-modules. Production of a large number of these modules is now ongoing. Results will be presented in a future daily image.

© ASTRON / A. van Duin

When the Sun had set and the darkness had set in, everyone ventured outside to be greeted by 4 operators and their optical telescopes. Through these, people connected(*) with objects like Jupiter, the Orion nebula, and Earth's lovely natural satellite the Moon. The highlight of the evening was the supernova (exploding star) in the M82 "cigar" galaxy.

All the while, operators, astronomers and other cognoscenti shared their deep knowledge of the cosmos with each other and the visitors. The pictures show the M51 "whirlpool nebula", the Pleiades open cluster and reflection nebula, and the galaxy M82 with the supernova (the bright spot towards the top left).

Since prolonged exposure to the night air chills the human body, everyone was invited to take a coffee break inside the Dwingeloo radio telescope. Here one could admire the newly restored and refurbished equipment. The CAMRAS team had set up a live audio stream of radio noise emitted by a pulsar many light-years away, received by the radio telescope itself.

The intranet site of the PV shows the activities for this year. See: https://intranet.astron.nl/commissies/pv/pv-activiteiten-lopend-jaar/pv-activiteiten-lopend-jaar

Special thanks to: Albert van Duin, Paul Boven, Roy Smits and Harm Munk for exerting themselves for this event.

(*) It is a curious but well-established fact that actually seeing an astronomical object through a telescope gives a (much) more acute sensation than seeing it as a picture in a book or on a screen.

© Leith Godfrey - ASTRON. Image Credits: M83 - NASA, ESA and the Hubble Heritage Team (WFC3/UVIS, STScI-PRC14-04a). MQ1 inset - W. P. Blair (Johns Hopkins University) & R. Soria (ICRAR-Curtin).

The powerful microquasar, called MQ1, was discovered in the inner disk of the spiral galaxy M83 (the "Southern Pinwheel"), as part of a multi-wavelength study of the X-ray source populations in this galaxy. The multi-wavelength campaign involves data from the Chandra X-ray observatory, Hubble Space Telescope, the Australia Telescope Compact Array, and the Australian Long Baseline Array.

The fortuitous state of the newly discovered microquasar provided a unique opportunity to robustly determine both the black hole mass and the time-averaged mechanical power (mechanical power refers to energy released in the form of jets and winds). Analysis of the X-ray emission properties of the accretion disk indicated that the compact object is a typical stellar mass black hole of order 10 solar masses (although possibly as high as 100 solar masses). Optical emission lines from shocked gas surrounding MQ1 enabled a measurement of the time-averaged mechanical power, which was found to be as much as 20 times the Eddington luminosity of the black hole.

Whilst it is well known that the radiative luminosity of the accretion flow onto a compact object cannot substantially exceed the Eddington limit, that is, the limit at which the outgoing radiation pressure impedes the inflow of matter, it remained unclear whether the mechanical power is bounded by this same limit. The discovery of MQ1 has demonstrated that mechanical power exceeding the Eddington limit is indeed possible over a sustained period. This result has strong implications for understanding accretion physics, and the physics of mechanical power output from black holes, at very high mass accretion rates.

The above image shows the Hubble Space Telescope view of the spiral galaxy M83, and the microquasar MQ1 (inset). The blue circle marks the position of the microquasar MQ1 in the inner disk of the galaxy. You can read the full article here http://www.sciencemag.org/content/343/6177/1330.full and a perspective piece "Testing the Limits of Accretion" here http://www.sciencemag.org/content/343/6177/1318.full.

© Sodankylä Geophysical Observatory

KAIRA uses LOFAR technology by ASTRON and has tile and aerial antennas like other LOFAR stations (although mounted differently to cope with Arctic conditions).

At around the moment of the peak of the storm, the westernmost tile antenna (H75) broke free from its anchor lines and was blasted across the high-band array. Debris from the tile then landed between the high- and low-band arrays, with fragments scattering through the low-band field causing additional damage.

The image above shows a map of the arrays, marking the location of the damage and has a plot in the top-right to show the wind speed and the moment of failure. The inset photographs from the top-left, going down then across are: a) using a snowmobile to gain access to the site, b) shoring timbers to protect the tiles adjacent to the missing tile, c) servicing tile anchors in bitter conditions, d) the remains of tile H75, and e) damaged aerials on the low-band field.

Makeshift repairs have now been carried out and KAIRA will run slightly impaired until summer when full access to the site can be achieved. Although the damage looks serious, it could have been a lot worse. We were saved further grief by heavy ice cover on the other tiles and packed snow around the aerials.

And during the storm and repair work, we continued observing!

More information and photographs can be found on the KAIRA web log.

© Martha Haynes (Cornell University)

© SpaSIA group of JIVE, V. Tudose (Space Science Institute, Romania), W. Wang (Shanghai Astronomical Observatory, China), Y. Yonekura and K. Fujisawa (National Astronomical Observatory of Japan), M. Kharinov (KVAZAR, Russia)

But on the way to that challenging experiment, the JIVE team conducted several trial observations involving new antennas as potential participants of the MEX-Phobos flyby observations. Among these new antennas were the new 65 m Tianma radio telescope of the Shanghai Astronomical Observatory, China (the upper left panel), and the 32 m Hitachi radio telescope of the National Astronomical Observatory of Japan in Ibaraki, Japan (the upper right panel). In the test observation of J1232-0224 at 8.4 GHz conducted on 18 Dec 2013, they were joined by the 32 m antennas in Zelenchukskaja and Badary (Russia), members of the KVAZAR network, a collective member of the EVN, Yamaguchi (Japan), operated by the Yamaguchi University and 25m Urumqui (China).

Textbook fringes were detected on all baselines (the lower left panel). A decent uv-coverage (the bottom centre panel) of this test allowed us to produce an image of the source (the bottom right panel) with the dynamic range of 1000 in less than 1 hour.

The test marked a very welcome potential addition of ~5000 m2 of collecting area to the Eastern extension of EVN and very valuable new baselines. And it paved the way for the successful MEX-Phobos flyby experiment. Stay tuned for more news on the latter!

© SKAO

AAMID deals with the specification, design and verification of the Mid Frequency Aperture Array (MFAA) component of the SKA. AAMID is part of the Advanced Instrumentation Program aimed at SKA2 and is one of the 10 consortia working on SKA design. AAMID concentrates on the antenna array and receivers.

Main partners in the consortium are: ASTRON (lead), Nancy Observatory, Bordeaux University, University of Manchester, University of Cambridge and KLAASA (China). Further contributions are expected from SKA-South Africa, Stellenbosch University, IT (Portugal) and University of Malta.

This week the AAMID consortium will have it's first All-Hands meeting, in Dwingeloo, 1-3 April. For information visit the meeting website: http://www.astron.nl/midaa2014 .

© astropix.nl

So far, only one supernova has been detected in Messier 81. This supernova, named SN 1993J, was discovered on March 28, 1993 by F. Garcia in Spain. It was the second brightest supernova seen in the 20th century. The brightest one was SN 1987A in the Large Magellanic Cloud. SN 1993J was also used to determine our distance to M81, it was estimated at 8.5 million light years (2.6 megaparsec)

M81 is interacting with two other galaxies, M82 and NGC3077, this process has stripped away gas from all three galaxies. Also due to this interaction, interstellar gas is falling into the centers of M82 and NGC3077, leading to vigorous star formation there.

M81 is also important in the history of the WSRT: the observations of the neutral hydrogen of M81 by Rots and Shane (1975) and the following analysis of the spiral arms by Rots and by Visser are one of the success stories of the WSRT of the seventies.

56 integrations of 10 minutes, 10 of 5 minutes and another 10 of 30 seconds were made on five separate nights in December 2013 and January 2014 with a 400mm telescope from Beilen. This High Dynamic Range (HDR) view is a combination of all integrations, the shorter ones fill in the usually overexposed center of this galaxy. Its colors show the different star populations, red/yellow for old stars, and blue for young stars. The pink patches visible in the spiral arms are star forming regions.

© Vereese van Tonder

A monotonic plane wave was synthesized by using the wave generators in the 4 back node fpga's on the UniBoard. Altogether 16 signals were generated, each with a progressive phase shift in order to approximate a plane wave arriving at 16 antenna's. The signals were then channelized by a polyphase filter bank after which the subband of interest was mapped to all 4 of the front node fpga's. The conjugate field matching weights for 16 signals in 180 (-90 deg to 90 deg) different directions were calculated and applied. After the complex weight multiplication the 16 signals were summed and integrated for 1 second.

Various experiments were conducted of which two are illustrated in the image above. One experiment entailed synthesizing a source with a DOA of 45 deg. It was expected and verified that the signals should add up constructively in this direction and destructively in the other directions, please see figure 1 in the above image. Further, the spacing between the elements were varied in terms of wavelength. This was done in order to verify that the main beam of the array becomes narrower for an overall length increase, please see figure 2 in the above image.

Vareese is from the group of David Davidson at Stellenbosch University in South Africa. She has spent the last 4 weeks at ASTRON as part of the MIDPREP program.

© Photowise / Sarel van Standen

Thanks to Sarel van Staden (Photowise), we got some tremendous pictures. Sarel was around at the site, as he also took some outstanding pictures of the first MeerKAT reflector being assembled and lifted into the final destination.

Additional information on the prototypes can be found on the previous daily images (17-06-2013 , 09-09-2013 and 10-03-2014, 17-03-2014 ). The images show the four environmental prototypes inside the WSRT bouwhal, the anchor test performed at the South Afrika Karoo SKA site, the shipment of the prototypes and the site where the prototypes will be realized.

These environmental prototypes are part of the Array Prototypes work package of the

SKA Mid-Frequency Aperture Array consortium

This project is part-financed by the Northern Netherlands (SNN), the European Regional Development Fund, and the "Peaks in the Delta" program of the Dutch Ministry of Economic affairs, Agriculture and Innovation.

© Ruud Visser

I will present analysis of HIFI water line profiles from the large WISH and WILL surveys of ~75 young lowmass YSOs. These will be placed within the context of ground based (J=5) CO observations, showing that both the HIFI water observations allow us to probe new components of the gas not previously observed from the ground.

The combination of the new and previously observed kinematic features probe all of the major components of protostellar systems, allowing a holistic study of infall, outflows and shocks as a function of source properties and evolutionary stage.

© Harm Jan Stiepel

The picture was taken at the time, and shows some very youthful looking giants. From the right: Ger de Bruyn, Joe Taylor, Robert Braun, Harvey Butcher, Richard Strom and (just) Helen Johnson. They are studying radio maps of the galactic foreground polarisation, which had then just been discovered with the WSRT.

Now Joe is back, to re-open the newly refurbished Dwingeloo telescope. The latter is now a National Monument, run by CAMRAS. Joe is a very hands-on scientist, who takes a great interest in amateur astronomy. He firmly believes that his deep understanding of observing instruments is an important part of his success.

As a radio amateur (call-sign K1JT), he is well-known for a number of programs and communication protocols. For instance, he wrote the widely used software(***) that makes it possible to bounce radio signals off the Moon with small telescopes. This was recently used to exchange the marriage vows of the CAMRAS chairman and his lovely wife.

This afternoon, there will be a mini-symposium in Joe's honor. Some of our new batch of youthful giants (and an occasional one from the old batch) will proudly show him what we have been up to since his last visit. The symposium will end with a discussion about possible amateur science cases for the venerable Dwingeloo Telescope.

(*) His research with Hulse on the Hulse-Taylor binary system offered the first indirect evidence for gravitational waves.

(**) Your humble servant, of course.

(***) The Weak Signal/Joe Taylor (WSJT) package.

© ASTRON, 2014.

The upgrade of a WSRT dish to APERTIF requires a significant amount of mechanical modifications: The MFFE system has to be removed, including coaxial cables, helium pipes and the heavy frame at the front of the feed cabin to which the MFFE was bolted. The entire chassis of the telescope is blasted and painted. A total of 129 coaxial RF cables is installed to bring the output signals of the PAF to the cabin on the ground. New cable trays and chains are mounted to smoothly support the cables. The rails in the feed cabin is lowered, new mounting points are created and the radome is replaced. Finally, the cabin on the ground is powered via a new distribution panel in the brick telescope house.

The work on RT4 was recently completed. The photos above show the end result of the operation and the heroes that performed the work. Thanks to their effort, RT4 can be equipped with a PAF in the very near future and used for APERTIF commissioning measurements.

© Harm Jan Stiepel

In 1956, when it was the largest radio telescope in the world, Prof Oort invited Queen Juliana to open it for the first time with the words: "Please push this button, if it pleases your Majesty". This time, Prof Joe Taylor was invited to push the same button(*) with almost the same phrase(**).

The picture shows the moment when the telescope dish showered(***) a large number of Earth balloons into the hands of an enthousiastic crowd of children. This was meant to symbolise the outreach that CAMRAS is planning, in addition to scientific experiments.

(*) The famous button is the blue-and-gold contraption in the right foreground. It was lovingly preserved by an unusually prescient employee, and was also used by Her to open the WSRT in 1970, and by Queen Beatrix to open the LOFAR telescope in 2010.

(**) The only difference was the honorific "your Nobility", referring to his 1993 Nobel Prize. The only other Nobel laureate present was Prof Martin Veltman (1999).

(***) The release of the balloons was not without problems, as behooves a ceremony about high science and technology. But, being amateurs, the CAMRAS people quickly solved the problem.

© DESP / ASTRON

The subrack consists of two UniBoards, four ADUs (Analog to Digital conversion Unit) and a PAC (Power And Clock distribution) board. The system will be used for AAVS (Aperture Array Verification System) in the LFAA (Low Frequency Aperture Array) SKA consortium.

For this application, the WSRT/APERTIF beamforming firmware was re-used and modified to a beamformer for 16 antennas, with a bandwidth of 300MHz, on a single UniBoard.

© ASTRON

On Wednesday 9 April at the Hannover Messe (the world's most important industrial fair), ASTRON, the University of Hamburg and Bielefeld University signed a contract for construction of a new German station close to Hamburg for the International LOFAR Telescope (ILT). The German LOng Wavelength consortium (GLOW) already has five operational LOFAR radio astronomy antenna stations, making it ASTRON's largest international partner in the ILT.

In the image from left to right: Ronald Halfwerk (ASTRON), Dominik Schwarz (Bielefeld University, Germany), Marco de Vos (ASTRON), Dutch state secretary Sander Dekker (department of Education, Culture and Science) and Marcus Brüggen (University of Hamburg, Germany).

More sensitivity in observations

The overall sensitivity and the ability of the ILT to image fine details in celestial objects are increased by adding more LOFAR stations at greater distances from the core (located in the northeast of the Netherlands).

Production of hardware for a LOFAR antenna station, which consists of hundreds of antennas and advanced electronics, is contracted out to industry to a value of more than 1 million euros.

LOFAR & Science

With LOFAR, astronomers can look back billions of years to a time before the first stars and galaxies were formed (the so-called ‘Dark Ages'), they can survey vast areas of the low-frequency radio sky, and they can be constantly on the lookout for some of the most energetic and burst-like events in the Universe. Researchers at the University of Hamburg, led by Prof. M. Brüggen, specialize in studying the formation and evolution of clusters of galaxies from the early Universe to the present era. The group at Bielefeld University, led by Prof. D. Schwarz, studies the distribution of galaxies on the largest observable distances in the Universe, which carry imprints from the era of cosmological inflation.

LOFAR is a SKA pathfinder

LOFAR is also a recognized science and technology pathfinder facility for the next-generation radio telescope, the Square Kilometre Array (SKA), which is being prepared by a global collaboration of countries and institutes, including the Netherlands and Germany. ASTRON has been an initiator and principal player in the SKA throughout. ASTRON is now taking many concepts of LOFAR, in particular the (real-time and off-line) handling of huge data streams, to the next level in preparation for the SKA.