Lunch Colloquium
Dr. Benjamin Winkel	SCHEDULED

Max-Planck-Institut für Radioastronomie

If you follow the news these days, you may get the impression that the upcoming cell-phone technology 5G will make all our lifes much much better. While many people hope that with this new technology you'll finally have internet everywhere and not only in the big cities, 5G is about more than that: low-power consumption, large possible bandwidths, and ultra-low latencies will be important for the internet of things (IoT), where every electronic device is online, but also for self-driving cars, and virtual reality applications. To achieve this goal, the international mobile telecommunications (IMT) industry is asking for a huge new share of the available radio spectrum. Radio astronomy at Gigahertz frequencies is likely to take a massive hit, as we are used to observe at frequencies where we have no allocation. For example, the next WRC is expected to allocate at least the frequencies between 24.25 - 27 GHz to IMT. But even to keep our own bands free of RFI is increasingly challenging. In my talk, I will explain how complex and time-consuming compatibility studies have been, in which we calculate the necessary distances between a 5G cell phone network and a radio observatory.

	Main Colloquium
Prof. Enrico Ruiz-Ramirez	CANCELED

Niels Bohr Institute, Copenhagen, and University of California, Santa Cruz

The source of about half of the heaviest elements in the Universe has been a mystery for a long time. Although the general picture of element formation is well understood, many questions about the nuclear physics processes and particularly the astrophysical details remain to be answered. Here I focus on recent advances in our understanding of the origin of the heaviest and rarest elements in the Universe

	Special Colloquium
Dr. Keith Bannister	SCHEDULED

ATNF/CSIRO, Sydney, Australia

Fast radio bursts are millisecond bursts of radio waves with unknown origin that come from objects at cosmological distances. We have been using the Australian Square Kilometer Array Pathfinder (ASKAP), a 36-dish radio interferometer situated in Western Australia, to find and localise these bursts. I will describe the ASKAP system, and recent results, including 3 sub-arcsecond localisations.

	Special Colloquium
Dr. Shivani Bhandari	SCHEDULED

CSIRO/ATNF, Epping, Australia

The ability to simultaneously observe a large area of the sky with the Australian Square Kilometre Array Pathfinder (ASKAP) has facilitated the wide-field blind searches for slow and fast radio transients. We have conducted an all-Southern sky survey in search for repeating FRBs with ASKAP by re-observing the sky at a different cadence. We have also conducted a pilot survey for slow transients and variable sources. In my talk, I will describe the results from both the slow and fast transient surveys highlighting the role of ASKAP in exploring a different part of the phase space.

	Special Colloquium
Dr. Florent Mertens	SCHEDULED

Kapteyn Astronomical Institute, University of Groningen, The Netherlands

Low-frequency observations of the redshifted 21-cm line promise to open a new window onto the first billion years of the cosmic history, allowing us to directly study the astrophysical processes occurring during the Epoch of Reionization (EoR) and the Cosmic Dawn (CD). This exciting goal is challenged by the difficulty of extracting the feeble 21-cm signal buried under astrophysical foregrounds orders of magnitude brighter and contaminated by numerous instrumental systematics. Several experiments such as LOFAR, MWA, and PAPER are currently underway aiming at statistically detecting the 21-cm brightness temperature fluctuations from the EoR. While no detection is yet in sight, considerable progress has been made recently. In this talk I will review the latest development of the LOFAR-EoR project, focusing on the calibration and foregrounds mitigation challenges. In this regards, I will present a new technique based on Gaussian Process Regression (GPR) able to separate the cosmological signal from the foregrounds contaminants. Finally, I will discuss our latest results, and future perspectives.

	Lunch Colloquium
Dr. Thomas L. Wilson	SCHEDULED

Max-Planck-Institut für Radioastronomie

In the radio range, observations show that there are deviations from Local Thermodynamic Equilibrium (LTE) in a number of atomic and molecular species. These deviations can be large, that is, the so-called strong maser lines of OH, water vapor, methanol and SiO. There are other situations in which the deviations are small, so the measurements are not so definite. Among these are the radio recombination lines of hydrogen and carbon. A discussion based on the history of measurements and interpretations is presented to provide a general explanation of maser action and a few specific examples.