Final Activity Report Summary - ONTHEFRINGE (Optical interferometry in training and in context) The astronomy discovery space is dramatically widening with the operation, building and planning of new ambitious infrastructures. A key aspect for the scientific return of these facilities is the training of its users. Another important aspect is that the know-how to use the facilities is unevenly spread throughout Europe. The series of summer schools ONTHEFRIGE was designed to train a new generation of young astronomers on optical interferometry with the Very Large Telescope Interferometer, run by the European Southern Observatory (ESO), the top optical facility in the world. The project consisted on a series of four two week schools with a strong practical, hands-on component. In schools, the theory of optical interferometry was presented and illustrated with practical applications and exercises that should be solved by the students in groups of two or three. At the end of the schools, the groups of students presented their observational proposal for the Very Large Telescope Interferometer and received feedback from seasoned observers and colleagues. Two schools where of data reduction type and two of astrophysical type. In the data reduction schools, the data reduction was emphasised with a mix of lectures and practical sessions. The astrophysical applications of optical interferometry were presented in seminars. The first data reduction school focused on the first generation instruments AMBER and MIDI. The second data reduction school focused on the PRIMA astrometric experiment and on imaging. In the astrophysical schools, two topics where optical interferometry is or will make important contributions were chosen - circumstellar disks and planets; active galactic nuclei. In the astrophysical schools, lectures surveyed the field under focus from the theoretical point of view to the experimental / observational one. Optical interferometry was put in context with complementary observational techniques such as radio / (sub-)mm interferometry and adaptive optics. All schools included a soft skills series of lectures / discussions on: presentation skills in the context of a contributed talk to a conference, scientific writing skills in the context of a refereed journal paper, observational proposal writing in the context of the Very Large Telescope Interferometer, career development in the context of searching a first job after the PhD, and a discussion on ethics in the context of the scientific practice. The project was organised by putting in balance the European dimension of optical interferometry with the contribution of experts from third countries. Attendants of the school were selected on motivation letter, institute of origin and relevance to their research area / expertise. Given the uneven spreading of optical interferometry know-how in Europe preference was given to at least one attendant from one institute and from countries with lower know-how in the area. The gender balance was 33 % female to 66 % male, reflecting both astrophysics and the fact the most of the lecturers were male. 264 students attended the schools, the vast majority being PhD students (152) and young postdocs (56). The schools took place in Goutelas (France), Porto (Portugal), Torun (Poland), Keszthely (Hungary). The last three locations have a less favoured region status. The project participants were the Centro de Astrofisica da Universidade do Porto (coordinator), the European Southern Observatory, the Laboratoire d'Études Spatiales et d'Instrumentation en Astrophysique de l'Observatoire de Paris, the Max-Planck-Institut für Astronomie, the INAF - Osservatorio Astrofisico di Arcetri, the Laboratoire d'Astrophysique de Grenoble, the Nicolaus Copernicus University in Torun and the Konkoly Observatory of the Hungarian Academy of Sciences (the last three with third party status).
