Giommi, P.P.GiommiPadovani, P.P.PadovaniOikonomou, F.F.OikonomouGlauch, T.T.GlauchPAIANO, SimonaSimonaPAIANOResconi, E.E.Resconi2025-02-182025-02-1820200004-6361http://hdl.handle.net/20.500.12386/36026The uncertainty region of the highly energetic neutrino IceCube200107A includes 3HSP J095507.9+355101 ($z$~=~0.557), an extreme blazar, which was detected in a high, very hard, and variable X-ray state shortly after the neutrino arrival. Following a detailed multi-wavelength investigation, we confirm that the source is a genuine BL Lac, contrary to TXS 0506+056, the first source so far associated with IceCube neutrinos, which is a "masquerading" BL Lac. As in the case of TXS0506+056, 3HSP J095507.9+355101 is also way off the so-called "blazar sequence". We consider 3HSP J095507.9+355101 a possible counterpart to the IceCube neutrino. Finally, we discuss some theoretical implications in terms of neutrino production.STAMPAenArticle10.1051/0004-6361/2020384232-s2.0-85089284817https://www.aanda.org/articles/aa/full_html/2020/08/aa38423-20/aa38423-20.htmlhttp://arxiv.org/abs/2003.06405v4FIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_10 High energy and particle astronomy – X-rays, cosmic rays, gamma rays, neutrinos