Kajava, J. J. E.J. J. E.KajavaMOTTA, Sara ElisaSara ElisaMOTTASanna, A.A.SannaVeledina, A.A.VeledinaDel Santo, M.M.Del SantoSEGRETO, ALBERTOALBERTOSEGRETO2020-12-232020-12-2320190035-8711http://hdl.handle.net/20.500.12386/29138MAXI J1820+070, a black hole candidate first detected in early 2018 March, was observed by XMM-Newton during the outburst rise. In this letter we report on the spectral and timing analysis of the XMM-Newton X-ray and UV data, as well as contemporaneous X-ray data from the Swift satellite. The X-ray spectrum is well described by a hard thermal Comptonization continuum. The XMM-Newton X-ray light curve shows a pronounced dipping interval, and spectral analysis indicates that it is caused by a moderately ionized partial covering absorber. The XMM-Newton/OM U-filter data do not reveal any signs of the 17 h orbital modulation that was seen later on during the outburst decay. The UV/X-ray cross-correlation function shows a complex shape, with a peak at positive lags of about 4 s and a precognition dip at negative lags, which is absent during the X-ray dipping episode. Such shape could arise if the UV emission comes partially from synchrotron self-Compton emission near the black hole, as well as from reprocessing of the X-rays in the colder accretion disc further out.STAMPAenArticle10.1093/mnrasl/slz0892-s2.0-85068959818000482696200004https://academic.oup.com/mnrasl/article-abstract/488/1/L18/5511901?redirectedFrom=fulltext2019MNRAS.488L..18KFIS/05 - ASTRONOMIA E ASTROFISICA