Institution: | (1) The Astronomical Institute, Utrecht;(2) Laboratory of Astrophysics, University of Rome and National Research Council, Italy;(3) The Astronomical Institute, Utrecht;(4) Sterrewacht Sonnenborgh , University of Utrecht, The Netherlands;(5) Sterrewacht Sonnenborgh , University of Utrecht, The Netherlands;(6) Hamburger Sternwarte, The Netherlands;(7) The Astronomical Institute, Utrecht;(8) The Astronomical Institute, Amsterdam |