Postal Address: Royal Observatory of Belgium, Solar Physics Department, Circular Avenue 3., B-1180 Brussels, Belgium
Email: hochedez at oma dot be or : JHochedez at spd dot aas dot org
Telephone: +32 2373 0302
Facsimile: +32 2374 9822
Jean-François Hochedez was born in France in 1964.
He
is married with Anne-Hélène
Téménidès
and has 3 children Anouk (1995), Pierre (1997) and Arthur (2000)
He received his PhD from the Paris XI University in 1990, and the degree of Ecole Centrale de Paris in 1987.
He is Work Leader at the Royal Observatory of Belgium.
He is the author of more than 60 research papers, and has been advising over 20 students during their thesis.
Jean-François Hochedez main interests in Astrophysics are the activity, and the variability of the Sun atmosphere.
To this aim, he is taking part of the analysis and interpretation of the SoHO Extreme ultraviolet Imaging telescope (EIT) dataset, addressing particularly the longer-term evolutions.
He is therefore also active in the field of image processing, and instrument in-flight operations and calibrations. He is Co-I of solar instruments and missions (EIT onboard SoHO, SECCHI onboard STEREO, SHARPP onboard SDO). He is co-Proposer of the Solar Orbiter ESA mission, and belongs to its Payload Working Group. He is the Principal Investigator of LYRA, an EUV/VUV radiometer that has been selected by ESA for flight onboard PROBA-2. He is the Instrument Scientist of SWAP, an EUV solar telescope also selected by ESA for PROBA-2.
He is, since 1998, the initiator and coordinator of the BOLD investigation for innovative wide bandgap UV imagers.
From 1992 till 1998, he contributed to, and partly led the EIT/SOHO & the EPIC/XMM calibrations on synchrotron beamlines at the Institut d’Astrophysique Spatiale, Orsay, France. In 1990 and 1991, he was Post-Doc at the Naval Research Laboratory, Washington, DC, USA participating to the EIT & LASCO / SoHO design and preparation. He worked on Ultraviolet Back-illuminated CCDs for his PhD at the Laboratoire de Physique Stellaire et Planétaire, Verrières, France.
Beyond solar physics, JFH is inquiring about other fields of astrophysics, Science, philosophy, anthropology, and Art. He is very much conscious of the responsibility the scientists and the artists share in the diffusion of knowledge, in the emergence of individual aspirations, and in the evolution of collective ambitions. He co-founded “Tête en l’Air”, a physics and astronomy popularization association.
My recent work contributes to assessing the smallest coronal features observed by EUV imagers. There are many reasons to push the spatial resolution to its limits; they will be essential to the ESA Solar Orbiter Science. Among the latest results, I have demonstrated a significant decrease in the rate of EUV ephemeral regions and brightenings with the rising activity cycle as seen in EIT-SoHO. In the context of a collaboration with the KIS, we use bright points to trace the solar differential rotation. I have also shown the correlation between the activity at small-scales and the occurrence of CMEs. The latter conveys Space Weather implications. These studies are ongoing, and promise further results.
To address the resolution issue, I have employed several different tools and approaches from advanced image and movie processing, statistics, archive management, to instrument operations, and in-flight recalibrations. I am for instance using multi-resolution (Continuous Wavelet Transform, Fast Level Set Transform), object tracking algorithms (Optical Flow), etc. Three PhD Mathematics students are now working in this context with my co-supervision. The above is a contribution to an ambitious ROB project, aiming at extracting “all” trends in the Solar Corona as seen by the EIT telescope.
I am involved in flight operations, participating particularly to the planning and analysis of the “high cadence shutterless sequences” of EIT, TRACE & SPIRIT. They currently happen four times a year following a proposal from the ROB team. The goal is to study fast events such as magneto-acoustic waves or reconnection sites, and their evolutions along the cycle(s).
Sustained involvement in instrumental efforts: My PhD work was directed towards ultraviolet sensitized CCDs in view of SoHO. Since then, I have carried out many characterizations of UV components including multilayers, synchrotron beamlines, cameras, integrated instruments, etc. I initiated and coordinate the BOLD project (Blind to the Optical Light Detectors) since 1998. It is an international initiative (40 scientists, 15 institutes) dedicated to the development of novel imaging photometric detectors for UV solar observations. It relies on the properties of wide bandgap semiconductor materials (viz. diamond and Al-Ga-nitrides), and CMOS APS. The investigation is proposed in view of the Solar Orbiter UV instruments, for which the expected benefits of the new sensors -visible blindness and radiation hardness- will be highly valuable.
In July 2002, I submitted as Principal Investigator the LYRA solar VUV radiometer based upon diamond BOLD detectors. It has been selected by ESA for PROBA-2, together with the SWAP EUV telescope of which I am Instrument Scientist. I finally have co-I responsibilities on Magritte/SHARPP of the NASA SDO, where the ROB Solar Physics Department is the co-PI institute.