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 2568 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 2568 is circled in red on the plot.

Hardness Ratios for Theta-2 Ori A, Obsid 2568
Aimpoint	HR₁ = (H-M)/(H+M)	HR₂ = (M-S)/(M+S)	HR₃ = (H-S)/(H+S)
ACIS-S	-0.583	-0.230	-0.717
ACIS-I	-0.536	0.019	-0.522

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 2568

Aimpoint Quantiles 25 % 25 % Error 50 % 50 % Error 75 % 75 % Error
ACIS-S keV 0.723 0.004 0.869 0.007 1.088 0.009

Q-norm 0.055 0.001 0.074 0.001 0.102 0.001
ACIS-I keV 0.781 0.006 0.971 0.008 1.278 0.013

Q-norm 0.062 0.001 0.087 0.001 0.127 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 2568
Aimpoint	Quantiles	25 %	25 % Error	50 %	50 % Error	75 %	75 % Error
ACIS-S	keV	0.723	0.004	0.869	0.007	1.088	0.009
ACIS-S	Q-norm	0.055	0.001	0.074	0.001	0.102	0.001
ACIS-I	keV	0.781	0.006	0.971	0.008	1.278	0.013
ACIS-I	Q-norm	0.062	0.001	0.087	0.001	0.127	0.002