AGAPE: andromeda gravitational amplification pixel experiment

The aim of the AGAPE (Andromeda Gravitational Ampli cation Pixel Experiment), experiment which has been rst proposed in June 1992 is to examine the distribution of massive astrophysical compact halo objects ((MACHO's) which possibly are in the galactic haloes and which could account for the missing dark matter. Those objects have a mass which is a fraction of solar mass and could be detected by gravitational microlensing: the light of a star is ampli ed when a MACHO is crossing its line of sight from the earth. This technique has been proposed by Paczy nski in 1986. The AGAPE collaboration applies this technique in an original way by using, as target stars, the stars of another galaxy without resolving them. The recent progresses in photometry with CCD allow now to see tiny variations of the surface brightness of a galaxy like M 31. Those tiny variations can be the result of a single microlensing event on the background stars contributing to the surface brightness. The AGAPE collaboration has now cumulated 82 nights of observation over 3 years at the 2m Bernard Lyot Telescope situated at Pic du Midi de Bigorre in the French Pyr en ees and has found variations compatible with microlensing events.