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-1 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-1 Ori A in Obsid 3 is circled in red on the plot.

Hardness Ratios for Theta-1 Ori A, Obsid 3
Aimpoint	HR₁ = (H-M)/(H+M)	HR₂ = (M-S)/(M+S)	HR₃ = (H-S)/(H+S)
ACIS-S	-0.509	0.214	-0.331
ACIS-I	-0.458	0.440	-0.021

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-1 Ori A, Obsid 3

Aimpoint Quantiles 25 % 25 % Error 50 % 50 % Error 75 % 75 % Error
ACIS-S keV 0.810 0.013 1.015 0.005 1.263 0.011

Q-norm 0.066 0.002 0.093 0.001 0.125 0.001
ACIS-I keV 0.927 0.006 1.073 0.009 1.394 0.023

Q-norm 0.081 0.001 0.100 0.001 0.142 0.003

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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-1 Ori A, Obsid 3
Aimpoint	Quantiles	25 %	25 % Error	50 %	50 % Error	75 %	75 % Error
ACIS-S	keV	0.810	0.013	1.015	0.005	1.263	0.011
ACIS-S	Q-norm	0.066	0.002	0.093	0.001	0.125	0.001
ACIS-I	keV	0.927	0.006	1.073	0.009	1.394	0.023
ACIS-I	Q-norm	0.081	0.001	0.100	0.001	0.142	0.003