Born in 1997, the Whole Earth Blazar Telescope (WEBT) is a network of optical, near-infrared, and radio observers who in concert have the capability to obtain continuous, high-temporal-density monitoring of blazars.
Because of the longitude diversity of participating observers, it is feasible to obtain continuous optical observations, with observing activity moving from east to west around the world as the Earth rotates.
Advanced amateur astronomers can contribute to blazar monitoring efforts.
The multifrequency WEBT data are extremely useful for understanding the continuum emission of blazars. This emission is observed to be extremely intense and to vary rapidly. It is thought to originate in a relativistic plasma jet which is thought to be accelerated by a billion solar mass blackhole.
The radio-to-optical light curves obtained by the WEBT are usually studied in conjunction with observations at higher frequencies (ultraviolet, X- and gamma-rays), by satellites and ground-based TeV telescopes.