ArcTanGent Festival (also known as 'ATG') is a three-day British rock festival held annually at Fernhill Farm in Somerset, England since 2013. It is the most popular British summer festival for math rock, post rock, progressive metal and experimental music. Previous performers include Explosions in the Sky, Glassjaw, Godspeed You! Black Emperor, Meshuggah, Coheed & Cambria, Shellac, The Dillinger Escape Plan, Converge, Russian Circles, Deafheaven, Cult of Luna, American Football, Battles, Public Service Broadcasting, And So I Watch You from Afar, 65daysofstatic, Fuck Buttons, La Dispute, TesseracT, Daughters and Mono.