The LBV nature of Romano's star (GR 290) in M 33

We report the first spectroscopic study of the LBV candidate GR 290 in M 33 (“Romano's star”) taken in February 2003, showing, besides prominent hydrogen and He i emission lines, the 4630–60 Å blend and weak He ii 4686 Å emission typical of Of stars. Our broad–band photometry shows that the star was observed during a phase of minimum optical luminosity, with $B=17.91\pm 0.03$, and a slightly positive colour index, which we tentatively attribute to an anomalous continuum energy distribution. We argue that GR 290 is indeed an LBV star presently in a high temperature phase, that should be followed – also in a short time – by ample spectroscopic and associated photometric variations.