1. Thüringer Landessternwarte Tautenburg (Germany)
2. Physikalisch-Technische Bundesanstalt (Germany)
3. INAF Osservatorio Astrofisico di Arcetri (Italy)
4. Georg-August-Univ. Göttingen (Germany)
5. European Organisation for Astronomical Research in the Southern Hemisphere (Germany)
6. Univ. of Uppsala (Sweden)
7. INAF Osservatorio Astronomico di Bologna (Italy)