Principal Investigator

Tim Axelrod

Research School of Astronomy and Astrophysics


Jon Smillie

Research School of Astronomy and Astrophysics



The MACHO project is examining the distribution
of dark matter in our galaxy. The stars in the Large
and Small Magellanic Clouds (two small galaxies near our own) and in the galactic bulge (the centre of our galaxy) are being monitored over a period of several years for instances of "microlensing". Microlensing occurs when a dark object (eg: a dead star or a black hole) passes in front of a star, causing an increase in the apparent brightness of this star due to the focussing effect of the object's gravity. Microlensing is a phenomena predicted by the Theory of Relativity, and the MACHO project was the first to actually observe it. By detecting multiple instances of microlensing, the MACHO project is able to construct a model of the overall distribution of dark matter in our galaxy. Current theories suggest that up to ninety percent of our galaxy's mass may be comprised of dark matter. The name MACHO is an acronym for Massive Compact Halo Object, a more precise name for dark matter objects.

How did the MDSS help in achieving the project's results?

The MACHO project generates significant amounts of both raw and reduced data. Since late 1992, MACHO has collected over 80,000 images of 74Mb each, and is expected to collect up to another 10,000 before the project terminates. Reduced data accounts for a further 600 gigabytes. In total, the MACHO database currently comprises some 6 terabytes of data, all of which must be readily accessable for analysis. Given these facts, simply finding sufficient storage for the project's needs is difficult. The ready availability of the MDSS made it a real solution.

The standard of support and service from ANUSF staff has been excellent. This has included not only assistance with using the facility, but also in debugging and improving the transfer mechanism over the University backbone network. We note that the Redwood media errors have made the MDSS difficult to use. This has been keenly felt by the MACHO project since we have a production requirement for continuous data storage and retrieval. However a high level of data integrity has been maintained, and no data entrusted to the MDSS has yet been lost.

Appendix A -