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 4473 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 4473 is circled in red on the plot.

Hardness Ratios for Theta-2 Ori A, Obsid 4473
Aimpoint	HR₁ = (H-M)/(H+M)	HR₂ = (M-S)/(M+S)	HR₃ = (H-S)/(H+S)
ACIS-S	-0.728	-0.076	-0.761
ACIS-I	-0.690	0.114	-0.624

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 4473

Aimpoint Quantiles 25 % 25 % Error 50 % 50 % Error 75 % 75 % Error
ACIS-S keV 0.767 0.005 0.898 0.007 1.088 0.007

Q-norm 0.061 0.001 0.078 0.001 0.102 0.001
ACIS-I keV 0.825 0.007 0.956 0.007 1.175 0.010

Q-norm 0.068 0.001 0.085 0.001 0.114 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 Theta-2 Ori A, Obsid 4473
Aimpoint	Quantiles	25 %	25 % Error	50 %	50 % Error	75 %	75 % Error
ACIS-S	keV	0.767	0.005	0.898	0.007	1.088	0.007
ACIS-S	Q-norm	0.061	0.001	0.078	0.001	0.102	0.001
ACIS-I	keV	0.825	0.007	0.956	0.007	1.175	0.010
ACIS-I	Q-norm	0.068	0.001	0.085	0.001	0.114	0.001