We report results of the monitoring campaign of the transient X-ray pulsar SMC X-2 performed with the Swift /XRT telescope in the period of Sept 2015 – Jan 2016 during the Type II outburst .
During this event bolometric luminosity of the source ranged from \simeq 10 ^ { 39 } down to several \times 10 ^ { 34 } erg s ^ { -1 } .
Moreover , we discovered its dramatic drop by a factor of more than 100 below the limiting value of L _ { lim } \simeq 4 \times 10 ^ { 36 } erg s ^ { -1 } , that can be interpreted as a transition to the propeller regime .
These measurements make SMC X-2 the sixth pulsating X-ray source where such a transition is observed and allow us to estimate the magnetic field of the neutron star in the system B \simeq 3 \times 10 ^ { 12 } G , that is in agreement with independent results of the spectral analysis .