MACHO Project Overview & Status
The Large Magellanic Cloud
Mount Stromlo Observatory, Canberra, Australia.
The 50" dome is in the centre foreground
Project Overview & Status : November 1994
The MACHO Project is a collaboration between scientists at the Mt. Stromlo
& Siding Spring Observatories, the Center for Particle Astrophysics at
the Santa Barbara, San Diego, & Berkeley campuses of the University of
California, and the Lawrence Livermore National Laboratory. Our primary
aim is to test the hypothesis that a significant fraction of the dark
matter in the halo of the Milky Way is made up of objects like brown dwarfs
or planets: these objects have come to be known as MACHOs, for MAssive
Compact Halo Objects. The signature of these objects is the occasional
amplification of the light from extragalactic stars by the gravitational lens
effect. The amplification can be large, but events are extremely rare: it is
necessary to monitor photometrically several million stars for a period of
years in order to obtain a useful detection rate. For this purpose we have
built a two channel system that employs eight 2048*2048 CCDs,
mounted on the 50 inch telescope at Mt. Stromlo. The high data
rate (several GBytes per night) is accommodated by custom electronics and
on-line data reduction.
We have taken ~27,000 images with this system since June 1992.
Analysis of a subset of these data has yielded databases containing light
curves in two colors for 8 million stars in the LMC and 10 million in the
bulge of the Milky Way.
A search for microlensing has turned up
four candidates toward the Large Magellanic Cloud and 45 toward
the Galactic Bulge. Papers describing these results can be found in the
Publications section of the MACHO Web page.