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About Me

My interest in astronomy goes back to my early high school days when many nights were spent behind a 6-cm lens telescope. The highlight was (and still is) the appearance of the gigantic but swift comet West in 1976 (if only I had been able to see McNaught in 2007..).

Utrecht University was responsible for my academic education, with an undergraduate research involving photometry (in the "Utrecht Photometry System", of course) of the common-envelope binary AW Uma, studying its morphology and orbital decay. Close binaries never left my world since. As a graduate student at the Space Research Organization Netherlands in Utrecht, I got into X-ray binaries, which is a subset of close binaries where one component is a neutron star or black hole. The observations were done with the COded Mask Imaging Spectrometer on the Mir space station.

After earning my PhD, I left Utrecht to go to Los Alamos National Laboratory and NASA's Goddard Space Flight Center (through the NRC) to get acquainted, as a postdoc, with gamma-ray bursts and X-ray pulsars. Studying gamma-ray bursts in those days mostly meant doing population studies. Fortunately, that is now completely different!

When I returned to the Netherlands, I was so lucky to become part of the Italian/Dutch BeppoSAX project, in particular the Wide Field Cameras which revolutionized GRB research through quick and accurate localizations of these previously blurry celestial flashes, thus enabling the detailed study of individual bursts.

Since 2002 I am permanent staff member of SRON, at the High Energy Astrophysics Division where I did my PhD and postdocs. Since the demise of the BeppoSAX project in 2002-2003, my focus of research has become thermonuclear X-ray bursts on neutron stars, as observed with BeppoSAX, RossiXTE, Chandra, XMM-Newton and INTEGRAL. The past decade has seen the discovery of two new types of X-ray bursts: super- and intermediately long bursts that can last up to the good part of a day. Ergo, many more photons. Hopefully these will one day (soon) enable the first-time unambiguous measurement of gravitational redshift on the most compact visible object to be found in the universe - the neutron star. Most recently, my scientific work has focused even more, now on dynamical phenomena resulting from thermonuclear bursts (radiative pressure, expanding shells, accretion flows and their interaction).

A few times I taught, with Norbert Langer, a course on stellar transients at Utrecht University. This promises to be an as exciting field of expertise in optical and radio astronomy in the coming years as it was in the past few decades in X-ray astronomy. Unfortunately, without Utrecht University which incomprehensibly decided to terminate its long-lasting and still highly succesful astronomical institute.

My experience with hardware pertains to designing the coded masks for the BeppoSAX WFCs and HETE-II, and optimizing the optical design of the Wide Field Monitor intended for the ESA M3 proposal 'LOFT'. Furthermore, I have done my share of and pre- and in-flight calibrations of various instruments and simulation studies for future instruments such as SXG-MOXE, XEUS mirrors and LOFT-WFM.

Updated: 2014-01-03 by JZ