Spectroscopic lower limit to the redshift (z>0.863) of the BL Lac object 4FGL J2255.1+2411, a possible neutrino source

The most significant possible neutrino source found by the ANTARES collaboration is the BL Lac object MG3J225517+2409 associated to the gamma-ray source 4FGLJ2255.1+2411, and also associated with an IceCube high-energy track (Antares collaboration, 2019ICRC,36,840A).