Pixel lensing: Microlensing towards M31
  Pixel lensing is gravitational microlensing of unresolved stars. The main
target explored up to now has been the nearby galaxy of Andromeda, M31. The
scientific issues of interest are the search for dark matter in form of compact
halo objects, the study of the characteristics of the luminous lens and source
populations and the possibility of detecting extra-solar (and extra-galactic)
planets. In the present work we intend to give an updated overview of the
observational status in this field.
