The Whole Earth Blazar Telescope (WEBT) is an international collaboration aimed at carrying out and interpreting both photometric and polarimetric observations in the optical, near infrared (NIR) and radio bands of blazars, i.e. peculiar active galactic nuclei (AGN) characterized by relativistic jets of plasma oriented in close directions to the line of sight from Earth.

The WEBT collaboration conducts internationally coordinated campaigns involving dozens of telescopes, including small ones, spread across all continents in order to guarantee continuous temporal coverage and a high density of measurements over time.

Diagram of the structure of a blazar - Credits: WEBT.

Both professional and amateur groups participate in the collaboration, and collaborations with groups that conduct observations in the high energy bands, from ultraviolet, to X-rays and gamma rays, are intense.

The leadership of the collaboration is entrusted to Claudia Raiteri and Massimo Villata, of INAF - Astrophysical Observatory of Turin.


More info
https://www.oato.inaf.it/blazars/webt/

Visible band light curve of the CTA102 blazar, constructed with measurements carried out by the various telescopes of the WEBT collaboration and represented with different colours. The availability of many instruments spread across the world allows dense and continuous sampling of the luminosity trend which is variable, irregular and unpredictable - Credits: WEBT.

OAB and WEBT

The contribution of the Brera Astronomical Observatory is guaranteed by Giacomo Bonnoli, who coordinates the activities of some telescopes in Italy (Astronomical Observatory of the University of Siena, Provincial Observatory of Montarrenti - Siena, and their collaborators) and in Spain (Sierra Nevada Observatory, Calar Alto Observatory) and to coordinate joint observation campaigns with the MAGIC Telescopes.

Sloan Digital Sky Survey image of blazar Markarian 421, illustrating the bright nucleus and elliptical host galaxy - Credits: SDSS..