1. Universidad de Concepción, Departamento de Astronomía, Casilla 160-C, Concepción, Chile
2. Astronomical Institute of the Academy of Sciences of the Czech Republic, Boční II 1401/1, Prague, 141 00, Czech Republic
3. Astronomical Observatory, Volgina 7, 11060 Belgrade 38, Serbia
4. Isaac Newton Institute of Chile, Yugoslavia Branch
5. ESO - European Organization for Astronomical Research in the Southern Hemisphere, Casilla 19001, Santiago 19, Chile
6. Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, USA
7. Warsaw University Observatory, Al. Ujazdowskie 4, PL-00-478 Warszawa, Poland
8. Departamento de Matemática y Física Aplicadas, Universidad Católica de la Santísima Concepción, Alonso de Rivera 2850, Concepción, Chile
9. Indian Institute of Astrophysics, II Block Koramangala, Bangalore 560034, India
10. Institut Utinam, CNRS UMR6213, Univ. Bourgogne Franche-Comté, OSU THETA, Observatorie de Besançon, BP 1615, F-25010 Besançon Cedex, France
11. Instituto de Astronomía y Ciencias Planetarias, Universidad de Atacama, Copayapu 485, Copiapó, Chile
12. Instituto de Física y Astronomía, Universidad de Valparaíso, Valparaíso, Chile
13. Astronomy Research Unit, PO Box 3000, FL-90014 University of Oulu, Oulu, Finland
14. Turitea Observatory, Palmerston North, New Zealand