The light curve of MAXI J1659-152 over the past 11 yr as observed by MAXI/GSC. The inset shows the evolution of the hardness ratio during the 2010 outburst. The hardness is defined as the ratio of the counts detected at 4.0–10.0 keV (hard X-ray bands) to the counts detected at 2.0–4.0 keV (soft X-ray bands) of MAXI/GSC. The red circles in inset correspond to dates with observations by RXTE/PCA, with two points (SP2 and SP3) overlapping.