RAITERI, Claudia MariaClaudia MariaRAITERIVILLATA, MassimoMassimoVILLATACarosati, DDCarosatiBenítez, EEBenítezKurtanidze, S OS OKurtanidzeGupta, A CA CGuptaMirzaqulov, D OD OMirzaqulovD'AMMANDO, FILIPPOFILIPPOD'AMMANDOLarionov, V MV MLarionovPursimo, TTPursimoAcosta-Pulido, J AJ AAcosta-PulidoBaida, G VG VBaidaBALMAVERDE, BarbaraBarbaraBALMAVERDEBonnoli, GGBonnoliBorman, G AG ABormanCARNERERO MARTIN, Maria IsabelMaria IsabelCARNERERO MARTINChen, W-PW-PChenDhiman, VVDhimanDi Maggio, AADi MaggioEhgamberdiev, S AS AEhgamberdievHiriart, DDHiriartKimeridze, G NG NKimeridzeKurtanidze, O MO MKurtanidzeLin, C SC SLinLopez, J MJ MLopezMarchini, AAMarchiniMatsumoto, KKMatsumotoMujica, RRMujicaNakamura, MMNakamuraNikiforova, A AA ANikiforovaNikolashvili, M GM GNikolashviliOkhmat, D ND NOkhmatOtero-Santos, JJOtero-SantosRizzi, NNRizziSakamoto, TTSakamotoSemkov, EESemkovSigua, L AL ASiguaStiaccini, LLStiacciniTroitsky, I SI STroitskyTsai, A LA LTsaiVasilyev, A AA AVasilyevZhovtan, A VA VZhovtan2022-03-222022-03-2220210035-8711http://hdl.handle.net/20.500.12386/31775Blazar S5 0716+714 is well-known for its short-term variability, down to intraday time-scales. We here present the 2-min cadence optical light curve obtained by the TESS space telescope in 2019 December-2020 January and analyse the object fast variability with unprecedented sampling. Supporting observations by the Whole Earth Blazar Telescope Collaboration in B, V, R, and I bands allow us to investigate the spectral variability during the TESS pointing. The spectral analysis is further extended in frequency to the UV and X-ray bands with data from the Neil Gehrels Swift Observatory. We develop a new method to unveil the shortest optical variability time-scales. This is based on progressive de-trending of the TESS light curve by means of cubic spline interpolations through the binned fluxes, with decreasing time bins. The de-trended light curves are then analysed with classical tools for time-series analysis (periodogram, autocorrelation, and structure functions). The results show that below 3 d there are significant characteristic variability time-scales of about 1.7, 0.5, and 0.2 d. Variability on time-scales $\lesssim 0.2$ d is strongly chromatic and must be ascribed to intrinsic energetic processes involving emitting regions, likely jet substructures, with dimension less than about 10<SUP>-3</SUP> pc. In contrast, flux changes on time-scales $\gtrsim 0.5$ d are quasi-achromatic and are probably due to Doppler factor changes of geometric origin.STAMPAenArticle10.1093/mnras/staa35612-s2.0-85100328749https://academic.oup.com/mnras/article/501/1/1100/5986629?login=truehttp://arxiv.org/abs/2011.06493v12021MNRAS.501.1100RFIS/05 - ASTRONOMIA E ASTROFISICA