IXPE, NuSTAR, and NICER light curves (count s⁻¹) of each source. The second and fourth rows in each panel show the IXPE hard color (5–8 keV/3–5 keV) and the NuSTAR hard color (10–20 keV/6–10 keV), respectively. Open circles indicate data points not simultaneous with IXPE observation. Blue and red regions correspond to the HB and FB, respectively (see also Sects. 4 and 5 for more details). Time bins of 200 s were used for IXPE and NuSTAR, and 50 s for NICER. (a) Cyg X-2. (b) XTE J1701–462. (c) GX 5–1. (d) Sco X-1. (e) GX 340+0. (f) GX 349+2.