Current Status of the Microlensing Surveys

Abstract

The ongoing microlensing searches have generated more photometric measurements of pulsating stars than all previous observing projects combined. In particular, OGLE has made ~ 340,000 B, V, and I-band measurements of ~ 1,300 Cepheids in the Large Magellanic Clouds accessible over Internet. Microlensing searches contributed to the development of very efficient image subtraction software which works best in crowded fields. This suggests the use of a period - flux amplitude rather than period - luminosity relation for the Cepheids for distance determination, as the flux amplitude is directly measurable with the image subtraction, and it is not biased by crowding. Future projects will dramatically increase the data rate, will provide all-sky coverage and a complete census of variables, including pulsating stars, to the ever fainter limits. Time will show which approach, a small number of large teams or a large number of small teams, will be more productive.