Left: fit parameter degeneracy for the 1, 3, and 5σ levels of ACIS – PN for the (0.7−7) keV energy band. ACIS-I (red square) and ACIS-S (black triangle) HIFLUGCS subsamples are shown versus the PN data (for all ACIS data combined, see Fig. B.4, top left panel, gray ellipse). Equality of temperatures for two instruments is given for a = 1 and b = 0. The deviation in σ from equality is given in the legend. Right: as in the left panel but only 3σ levels (gray and red ellipses) of ACIS – PN with temperatures taken from N10 (0.5−7 keV energy band, black triangle) and complete ACIS – PN of this work (0.7−7 keV energy band, red square).