The long-term optical evolution of the black hole candidate MAXI J1659−152

We present 5 years of optical and infrared data of the black hole candidate MAXI J1659-152 covering its 2010 outburst, decay and quiescence. Combining optical data taken during the outburst decay, we obtain an orbital period of 2.414 $\pm$ 0.005 h, in perfect agreement with the value previously measured from X-ray dips. In addition, we detect a clear H$\alpha$ excess in MAXI J1659-152 with data taken during the outburst decay. We also detect a single hump modulation most likely produced by irradiation. Assuming that the maximum occurs at orbital phase 0.5, we constrain the phase of the X-ray dips to be ~ 0.65. We also detect the quiescent optical counterpart at r' = 24.20 $\pm$ 0.08, I = 23.32 $\pm$ 0.02 and H = 20.7 $\pm$ 0.1. These magnitudes provide colour indices implying an M2-M5 donor star assuming 60% contribution from a disc component in the r'-band.