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. Theta-2 Ori A in Obsid 3 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. Theta-2 Ori A in Obsid 3 is circled in red on the plot.

Hardness Ratios for Theta-2 Ori A, Obsid 3
Aimpoint	HR₁ = (H-M)/(H+M)	HR₂ = (M-S)/(M+S)	HR₃ = (H-S)/(H+S)
ACIS-S	-0.360	-0.309	-0.601
ACIS-I	-0.284	-0.076	-0.352

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 Theta-2 Ori A, Obsid 3

Aimpoint Quantiles 25 % 25 % Error 50 % 50 % Error 75 % 75 % Error
ACIS-S keV 0.694 0.007 0.869 0.007 1.132 0.011

Q-norm 0.051 0.001 0.074 0.001 0.108 0.001
ACIS-I keV 0.781 0.007 0.956 0.009 1.321 0.019

Q-norm 0.062 0.001 0.085 0.001 0.133 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 Theta-2 Ori A, Obsid 3
Aimpoint	Quantiles	25 %	25 % Error	50 %	50 % Error	75 %	75 % Error
ACIS-S	keV	0.694	0.007	0.869	0.007	1.132	0.011
ACIS-S	Q-norm	0.051	0.001	0.074	0.001	0.108	0.001
ACIS-I	keV	0.781	0.007	0.956	0.009	1.321	0.019
ACIS-I	Q-norm	0.062	0.001	0.085	0.001	0.133	0.002