X-ray Hardness and Quantiles

Hardness ratios calculated from the predicted ACIS-S Aimpoint spectra of selected X-Atlas targets (× = hot star; ◊ = cool star). S, M, and H are the total predicted counts in the passbands listed on the plot. Cyg OB2 7 in Obsid 2572 is circled in red on the plot.

Hardness ratios calculated from the predicted ACIS-I Aimpoint spectra of selected X-Atlas targets (× = hot star; ◊ = cool star). S, M, and H are the total predicted counts in the passbands listed on the plot. Cyg OB2 7 in Obsid 2572 is circled in red on the plot.

Hardness Ratios for Cyg OB2 7, Obsid 2572
Aimpoint	HR₁ = (H-M)/(H+M)	HR₂ = (M-S)/(M+S)	HR₃ = (H-S)/(H+S)
ACIS-S	-0.118	0.566	0.481
ACIS-I	-0.107	0.703	0.644

X-ray Quantiles

Quantile-based color-color diagram: (m = Q₅₀ = (E₅₀ - E_lo)/(E_hi - E_lo)). E_lo = 0.3 keV; E_hi = 8.0 keV

View complete listing of X-Atlas Spectral Metrics (Hardness, Quantiles).

Quantiles for Cyg OB2 7, Obsid 2572

Aimpoint Quantiles 25 % 25 % Error 50 % 50 % Error 75 % 75 % Error
ACIS-S keV 1.073 0.011 1.336 0.012 1.832 0.019

Q-norm 0.100 0.001 0.135 0.002 0.199 0.002
ACIS-I keV 1.117 0.012 1.380 0.014 1.818 0.019

Q-norm 0.106 0.002 0.140 0.002 0.197 0.002

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ACIS-S hot stars JPG Postscript	ACIS-S cool stars JPG Postscript
ACIS-I hot stars JPG Postscript	ACIS-I cool stars JPG Postscript

Quantiles for Cyg OB2 7, Obsid 2572
Aimpoint	Quantiles	25 %	25 % Error	50 %	50 % Error	75 %	75 % Error
ACIS-S	keV	1.073	0.011	1.336	0.012	1.832	0.019
ACIS-S	Q-norm	0.100	0.001	0.135	0.002	0.199	0.002
ACIS-I	keV	1.117	0.012	1.380	0.014	1.818	0.019
ACIS-I	Q-norm	0.106	0.002	0.140	0.002	0.197	0.002