Optical identification of X- and gamma-ray sources: the use of existing data

Summary We briefly discuss the use of existing astronomical data, mainly deep optical observations performed in order to obtain galaxy and star counts, for the identification of gamma-ray burst sources in particular and of newly discovered X- and gamma-ray sources in general. Use of such data cannot only reduce the amount of required telescope time but also, in comparison with present-day observations, allow the search for variability and proper motion of candidate optical counterparts over a time span of several years. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.