High-frequency (ν ^Hi ₁₀) QPO of a 10  M _☉ black hole plotted against their peak ratios. The upper curve is drawn for a = 0.999, while the lower curve is drawn for extreme peak ratios with a short extension curve (straight line) for a = −0.999. The upper curve helps us to estimate maximum possible mass values, while the lower curve gives minimum possible mass of the microquasars from Equation (26).