Searching for Dark Matter via Gravitational Microlensing: A report from
the MACHO project.

Christopher Stubbs
Department of Astronomy
&
Department of Physics
University of Washington


The MACHO project uses the principle of gravitational lensing to search
for compact objects of mass 10^{-7} to 100 solar masses in the halo, disk
and bulge of our Galaxy.  The main objective of the project is to detect
and/or constrain the existence of compact objects (MACHOS) in the dark
matter halo of the Galaxy.  The lack of short duration lensing events
towards the LMC has allowed us to exclude the possibility that 
objects in the mass range 10^{-6} to 0.01 solar masses constitute
the Galactic dark matter, which is a very important new limit on 
astrophysical dark matter candidates.  We have however detected a
rate of lensing events lasting many tens of days that is 
substantially more than the expected number of "background" events
from known stellar populations, and the source of this new lensing
population is the topic of considerable current debate.