Detection of brown dwarfs by the micro-lensing of unresolved stars

Astron.Astrophys. 277 (1993) 1-9 The presence of brown dwarfs in the dark galactic halo could be detected through their gravitational lensing effect and experiments under way monitor about one million stars to observe a few lensing events per year. We show that if the photon flux from a galaxy is measured with a good precision, it is not necessary to resolve the stars and besides more events could be observed.