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 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-1 Ori A in Obsid 2568 is circled in red on the plot.

Hardness Ratios for Theta-1 Ori A, Obsid 2568
Aimpoint	HR₁ = (H-M)/(H+M)	HR₂ = (M-S)/(M+S)	HR₃ = (H-S)/(H+S)
ACIS-S	-0.221	0.460	0.266
ACIS-I	-0.174	0.600	0.476

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 2568

Aimpoint Quantiles 25 % 25 % Error 50 % 50 % Error 75 % 75 % Error
ACIS-S keV 0.971 0.006 1.248 0.007 1.657 0.011

Q-norm 0.087 0.001 0.123 0.001 0.176 0.001
ACIS-I keV 1.029 0.007 1.307 0.007 1.745 0.012

Q-norm 0.095 0.001 0.131 0.001 0.188 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-1 Ori A, Obsid 2568
Aimpoint	Quantiles	25 %	25 % Error	50 %	50 % Error	75 %	75 % Error
ACIS-S	keV	0.971	0.006	1.248	0.007	1.657	0.011
ACIS-S	Q-norm	0.087	0.001	0.123	0.001	0.176	0.001
ACIS-I	keV	1.029	0.007	1.307	0.007	1.745	0.012
ACIS-I	Q-norm	0.095	0.001	0.131	0.001	0.188	0.002