ASTRON/JIVE Daily Image

CAMRAS 5 years old

Andre' van Es — Fri, 03 Feb 2012 00:00:00 GMT

On January 29th 2007, five years ago, the C.A.Muller Radio Astronomical Station (CAMRAS, http://www.camras.nl/ ) was founded. The organisation is named after Prof Ir Muller, the first Director of the 25m Dwingeloo Telescope, and one of the great pioneers of Dutch radio astronomy. The picture shows Maria van der Hoeven (Dutch Minister of Education at that time) handing over the key to the telescope to Remco den Besten (first chairman of CAMRAS).

When it was built in 1956, it was the largest fully steerable radio telescope in the world. Thanks to Prof Muller, its receivers were stable, sensitive, and unusually well-shielded against interference. During its four decades at the forefront of scientific inquiry, the telescope investigated the dynamics of our Galaxy and made several important scientific discoveries. It also paved the way for its even more famous successors, the WSRT and LOFAR.

The CAMRAS volunteers now maintain and operate it. They have achieved a lot in these five years: they put the instrument back in operation, and there are advanced plans to renovate it. All this has resulted in getting the Dwingeloo Telescope designated as a monument ("rijksmonument"). The refurbished telescope is now used for several activities such as:

- educational excursion os astronomy and technology, for instance CAMRAS participates in the "Sterrenkijkdagen", "Open Monumentendag", "Nacht van de Nacht" and intents to join the Global Star Party at April 28th this year

- the telescope is used by radio amateurs moon bouncing (for communication via the moon)

- experiments by amateur astronomers

- cultural events such as OPTICKS ( http://www.opticks.info/blog/ )and the Soundlab project part of "Oerol spoelt aan" in Drenthe

To celebrate the 5th anniversary a symposium is organised today that will address the scientific importance of the instrument, the achievements of CAMRAS in the past five years and the possibilities of the renovated Dwingeloo Telescope in the coming decades.

The work in the past five years would not have been possible without donations and sponsors, and of course volunteers. The symposium is our way of thanking everyone for helping CAMRAS achieve all this in the first five years. And to encourage everyone to keep supporting CAMRAS, so we can continue to share our enthusiasm for science and technology in using this wonderful instrument.

Icy Report

Jan Noordam — Sun, 05 Feb 2012 00:00:00 GMT

This picture was taken last thursday (2 Feb 2012) on the little pond close to the Dwingeloo observatory. When it is freezing, people go there during lunch to test the thickness and quality of the ice, and to dream of the skating ahead. As you can see, the ice was of an unusual quality, and the wheather reports promised a week of effortless gliding from village to village along the ubiquitous Dutch waterways. There was even talk about the possibility of an "Elfstedentocht", the gruelling 220 km around the eleven cities of Friesland.

Unfortunately, amidst great groaning and gnashing of teeth (especially by the grizzled variety of Dutchmen), a single morning of snow on Friday seemed to ruin it all. The pristine mirror of ice was covered by 5-15 cm of useless prettiness, which made it difficult to see the weak spots, or the rough bits that can turn the graceful flight on an eagle into the undignified landing of a Gooney bird. Moreover, the insulating snow slowed the further thickening of the ice.

But fortunately, there was no thawing, so the snow did not spoil the ice itself. And, since skating is big business in the Netherlands, a huge army of chaps with sweeping devices of all kinds and sizes started to clean trails all over the place. You can even buy a map of Friesland that shows the routes that are guaranteed to be swept.

So, if you have dealings with ASTRON or JIVE, do not be surprised if your interlocutor is difficult to find in the coming week. While the greybeards are away, trying to impress each other (and themselves) on the frozen lakes and canals, there will be a skating party for the rest on tuesday, on this same pond, complete with "koek en zopie".

Today's colloquium: LSST: a digital color movie of the Universe

Colloquium — Mon, 06 Feb 2012 00:00:00 GMT

The Large Synoptic Survey Telescope (LSST), the top ground-based priority in the US Astro2010 Decadal Survey report, will carry out an imaging survey covering the sky that is visible from Cerro Pachon in Northern Chile. With about 1000 observations of half the sky in six optical bands over a 10-year period, the LSST data will enable faint time-domain astronomy and a deep stack across half the sky reaching hundred times fainter flux limit than the SDSS survey.

The resulting hundreds of petabytes of imaging data for about 20 billion objects will be used for scientific investigations ranging from the properties of near-Earth asteroids and brown dwarfs, to characterizations of dark matter and energy from strong and weak lensing, galaxy clustering, and distant supernovae. These data will represent a treasure trove for follow-up programs using other ground and space-based telescopes, such as fast-response fast-cadence photometric observations and spectroscopy, as well as for facilities operating at non-optical wavelengths and for gravitational wave programs.

I will summarize the main LSST science drivers, and will illustrate them using ongoing work based on SDSS and other data, with emphasis on quasar variability, the Milky Way structure, and the Solar System studies.

Johan Hamaker turns 75

Jan Noordam — Tue, 07 Feb 2012 00:00:00 GMT

In our AJDI series of ex-employees who are still active for ASTRON (or JIVE) at 70, we now celebrate Johan Hamaker, who has turned 75 last week. For a few days each week he may be found in the "dinosaur room" in the prestigious Pavillion West, together with other giants like Wim Brouw and Hans van Someren Greve.

Johan started his career with impeccable credentials, since his JornaRoos (also in the picture) is a niece of Prof Oort, the father of Dutch radio astronomy. He is also a bit of an oddity, since he is the only ASTRON ingenieur who did not receive his education at a Technical University, but at the University of Amsterdam. Not surprisingly, he speaks 7 languages and knows his classics.

Johan was part of the original group that cheerfully over-engineered the WSRT, just to be on the safe side, and thus paved the way for its sustained excellence. At the same time, together with Jaap Baars, he introduced a less formal atmosphere at the Dwingeloo establishment, where people still addressed each other by surnames, wore jackets and ties, and the boss was always right. He was involved in various hardware projects, some of which were quite revolutionary, but his real interest was in the use of software for calibration. He rose to acting head of the "Computer Group" in the early eighties, and was seconded to Hawaii for a few years to help with the JCMT.

During the seventies, for good practical reasons, the WSRT data were processed in Leiden. Unfortunately, this meant that there was very little software in Dwingeloo (or even Westerbork) to inspect the data and develop new calibration techniques. Johan played a large role in redressing this unhealthy situation by developing software tools for imaging and display. This started the process that has kept ASTRON in the forefront of ultra-quality calibration to the present day.

His finest hour came around 1995, when he formulated the Measurement Equation, a closed-form matrix formalism that describes a generic radio telescope in full polarisation. Of course this was the culmination of a decades-long search by many people around the world, but he had the idea that made it all fall into place. It was just in time too, since it would have been unthinkable to embark on the new generation of giant radio telescopes (LOFAR, SKA, etc) without the Hamaker-Bregman-Sault (HBS) formalism.

Because he can afford to, Johan has been generous in admitting that he might (perhaps) have been too severe in his early prediction that LOFAR could never be calibrated. His unusual career is yet another demonstration that "it takes all kinds to make the difference".

LOFAR Special Session at AAS

Jason Hessels on behalf of the LOFAR AAS contingent — Wed, 08 Feb 2012 00:00:00 GMT

The recent meeting of the American Astronomical Society in Austin, Texas featured a Special Session entitled "First Science with LOFAR". This event was organized by Michael Wise and featured talks by Michael, George Heald, Chiara Ferrari, Jason Hessels, Ger de Bruyn, and Heino Falcke. These talks spanned the range of science topics that are now being done with LOFAR, including large-scale surveys, pulsars and transients, deep studies of galaxy clusters, the epoch of reionization, and cosmic rays.

For most of the session the room was packed with roughly 75-100 people (standing room only at the back). The response afterwards from our American and international colleagues was extremely positive!