%0 Journal Article %T Unbiased Long-Term Monitoring at TeV Energies %A Daniela Dorner %A HAWC and M@TE Collaborations %A Jos¨¦ Andr¨¦s Garc¨ªa-Gonz¨¢lez %A Mar¨ªa Magdalena Gonz¨¢lez %A Thomas Bretz %A on behalf of the FACT %J Galaxies | An Open Access Journal from MDPI %D 2019 %R https://doi.org/10.3390/galaxies7020051 %X For the understanding of the variable, transient and non-thermal universe, unbiased long-term monitoring is crucial. To constrain the emission mechanisms at the highest energies, it is important to characterize the very high energy emission and its correlation with observations at other wavelengths. At very high energies, only a limited number of instruments is available. This article reviews the current status of monitoring of the extra-galactic sky at TeV energies. View Full-Tex %U https://www.mdpi.com/2075-4434/7/2/51