MicroFUN

The Microlensing Follow-Up Network (μFUN, pronounced "micro-fun") is an informal group of observers who monitor high magnification gravitational microlensing events in the Milky Way's Galactic Bulge. Its goal is to detect extrasolar planets via microlensing of the parent star by the planet. μFUN is a follow-up network - they monitor microlensing events identified by survey groups such as OGLE and Microlensing Observations in Astrophysics (MOA).

In January 2009, μFUN merged with the Probing Lensing Anomalies NETwork (PLANET).

Organizations like μFUN provide a forum and a listserv for instant notification to amateur and professional astronomers all over the globe, so that microlensing events can be mined for all the information that can be gathered. Thus, amateur astronomers have an useful role in significant discoveries, as well as a clear and democratic path to authorship on any peer-reviewed scientific publications that result.

Gravitational lensing is an effect of Einstein's general relativity, which says that all matter bends light that passes by it. Strong gravitational lensing drastically alters the shape of an object on the sky; weak gravitational lensing slightly alters the shape of the object; and gravitational microlensing alters only the brightness of the object, instead of its shape. Gravitational lensing in general, and especially microlensing, has had a vast impact on astronomy, specifically in the search for extrasolar planets.

If a planet orbiting a star passes within our line of sight to that star, it very slightly changes the brightness of the star. These changes can last a few hours or a few days. Astronomers can estimate the ratio of the planet's mass to the star's mass, as well as the radius of the planet's orbit around the star, by comparing actual brightness measurements to theoretical models.

Expensive equipment is required to detect a microlensing event, but because of the magnification, less sophisticated telescopic equipment can monitor the magnified area for changes in brightness caused by planets. Equipment that is now available has become more efficient at detecting microlensing events, but this equipment is in high demand for all sorts of astronomical observations and cannot be dedicated to monitoring these events for disruptions caused by planets.

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Wikipedia