20 years of Observing Campaigns of OJ287: the Black Hole Binary Model as Witness of the Validity of the General relativity

A peculiar and controversial phenomenology is the periodicity of AGN and blazars. A representative case study with multifrequency radio-optical and X-ray data by Swift is presented, namely the BL Lac object OJ 287. The source is extensively monitored at radio and optical bands since 90's, with also coordinated intensive multifrequency campaigns. The data obtained during the last two observing multifrequency campaigns of 2004-2007 and 2015-2016, allowed to put some indirect tests of the General Relativity, under the assumption that the driving model is a binary supermassive black hole system with sub- parsec separation.