University Professor ... Jan. 2000 – present ... UofT
Professor ... July 1987 – Dec. 1999 ... CITA
Cross-appointed Professor July 1985 – present ... UofT Depts. of Astronomy and Physics
Acting Director...July 1994 – July 1995 ... CITA
Acting Director... July 1990 – July 1991 ... CITA
Associate Professor ... July 1985 – June 1987 ... CITA
Associate Professor ... Sept. 1985 – May 1987 ... Physics ... Stanford U.
Assistant Professor ... Sept. 1981 – August 1985 ... Physics ... Stanford U.
Sacker Visitor, Institute of Astronomy, Cambridge University, July-September 2008
Visiting Faculty Associate, Caltech, May-June 2008
Visiting Scientist, KIPAC and SLAC, April 2008
Visiting Scientist, Stanford Institute for Theoretical Physics, Stanford University, March 2008
Visiting Scientist, Institute for Astronomy, University of Hawaii, February 2008
Humboldt Fellow, Max Planck Institute for Astrophysics, October-January 2007
Visiting Professor, 1ere class ... Jan. 2003 – July 2003 ... University of Paris/IAP/IAS
Moore Scholar ... September 2002 – Dec. 2002 ... Caltech
Visiting Research Physicist ... Feb. – June 1995 ... Inst. for Theoretical Physics ... UC Santa
Directeur de Recherche Associ´e 4`eme ´echelon ... Aug. 1993 – Jan. 1994, Jan. – May 1996 ...Institut d’Astrophysique de Pari
Research Fellow ... July 1982 – Sept. 1983 ... Institute of Astronomy ... Cambridge U.
Postdoctoral Fellow/Lecturer ... Sept. 1978 – Sept. 1981 ... Astronomy ... U.C. Berkeley
Research Assistant ... Sept. 1973 – Sept. 1978 ... Kellogg Radiation Lab ... Caltech
Visiting Scientist ... Sept. 1976 – Mar. 1977 ... Nuclear Theory ... Neils Bohr Institute
Scientist ... July 1975 – Jan. 1976 ... Gamma Ray Astronomy ... JPL, Pasadena