X‐ray color‐magnitude diagram. The X‐ray color is defined as the logarithm of the ratio of X_soft (0.5–1.5 keV) corrected counts to X_hard (1.5–6.0 keV) corrected counts, and the magnitude is the logarithm of X_med (0.5–4.5 keV) corrected counts. For the sake of clarity, only a few error bars are shown; they represent the 1 σ error estimates given by Gehrels (1986). Our correction for photoelectric absorption has the effect of uniformly shifting the data +0.48 units on the left axis and +0.64 units on the bottom axis. The top and right axes provide the absorbed color and magnitude scales (superscript a), i.e., the observed colors and magnitudes uncorrected for absorption. CX 22 is not shown since it has 0 counts in X﹩_{\mathrm{soft}\,}﹩.