The Role of Small Telescopes in Modern Astronomy, October 14-15, 1996, Lowell Observatory


The Macho Project: Revealing Galactic Dark Matter and Surveying the Time Domain in Astronomy with a 50" Telescope

Kem H. Cook
LLNL

C. Alcock, D. Alves, S. Marshall, D. Minniti
LLNL

R. A. Allsman
ANUSF

T. S. Axelrod, K. C. Freeman, B. A. Peterson, A. W. Rodgers
MSSSO

A. C. Becker, C. W. Stubbs
CfPA/U Washington

D. P. Bennett
CfPA/LLNL

K. Griest, J. Guern, M. J. Lehner
CfPA/UCSD

M. R. Pratt
CfPA/UCSB

P. J. Quinn
ESO

W. Sutherland
Oxford

D. L. Welch
McMaster (The MACHO Collaboration)

The Macho Project is using both Magellanic Cloud and Milky Way bulge stars as sources to search for the gravitational microlensing signature of baryonic dark matter in the Milky Way's halo. These fields provide millions of relatively bright, resolved stars with lines of sight through much of the halo. This project requires a wide field system, and only a moderate aperture. The MACHO Project has the dedicated use of the Mt. Stromlo 1.27-m telescope. A prime focus corrector with an integrated beam splitter produces simultaneous, two color images on two 4096x4096 CCD arrays. In the past four years, we have collected about 50,000 0.5 square degree, dual color CCD images. A preliminary analysis of a photometry database spanning our first two years for about 10 million stars in the LMC and 12 million stars in the bulge has been been completed. We have detected about 10 microlensing events toward the LMC, and 100 microlensing events toward the bulge. These discoveries suggest a significant fraction of the Milky Way's halo is composed of Massive Compact Halo Objects (Machos) and that the Milky Way is a barred spiral with the bar oriented close to the line of sight to the galactic center. We have also cataloged about 40,000 variables stars in each of these directions. The combination of wide area coverage, dense temporal sampling, and uniformity of data product found in the Macho survey is yielding a new perspective on stellar pulsation physics, chemical and dynamical evolution of the observed populations, and may solve the discrepant RR Lyrae and Cepheid distance scales.


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