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 8A 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 8A in Obsid 2572 is circled in red on the plot.

Hardness Ratios for CYG OB2 8A, Obsid 2572
Aimpoint	HR₁ = (H-M)/(H+M)	HR₂ = (M-S)/(M+S)	HR₃ = (H-S)/(H+S)
ACIS-S	0.115	0.769	0.812
ACIS-I	0.121	0.836	0.869

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 8A, Obsid 2572

Aimpoint Quantiles 25 % 25 % Error 50 % 50 % Error 75 % 75 % Error
ACIS-S keV 1.234 0.003 1.540 0.004 2.008 0.007

Q-norm 0.121 0.000 0.161 0.000 0.222 0.001
ACIS-I keV 1.278 0.007 1.555 0.005 2.008 0.008

Q-norm 0.127 0.001 0.163 0.001 0.222 0.001

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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 8A, Obsid 2572
Aimpoint	Quantiles	25 %	25 % Error	50 %	50 % Error	75 %	75 % Error
ACIS-S	keV	1.234	0.003	1.540	0.004	2.008	0.007
ACIS-S	Q-norm	0.121	0.000	0.161	0.000	0.222	0.001
ACIS-I	keV	1.278	0.007	1.555	0.005	2.008	0.008
ACIS-I	Q-norm	0.127	0.001	0.163	0.001	0.222	0.001