  In this Letter, we report the results of spectroscopic and photometric
monitoring of the candidate luminous blue variable (LBV) WS1, which was
discovered in 2011 through the detection of a mid-infrared circular shell and
follow-up optical spectroscopy of its central star. Our monitoring showed that
WS1 brightened in the B, V and I bands by more than 1 mag during the last three
years, while its spectrum revealed dramatic changes during the same time
period, indicating that the star became much cooler. The light curve of WS1
demonstrates that the brightness of this star has reached maximum in 2013
December and then starts to decline. These findings unambiguously proved the
LBV nature of WS1 and added one more member to the class of Galactic bona fide
LBVs, bringing their number to sixteen (an updated census of these objects is
provided).
