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. EPSILON ERI in Obsid 1869 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. EPSILON ERI in Obsid 1869 is circled in red on the plot.

Hardness Ratios for EPSILON ERI, Obsid 1869
Aimpoint	HR₁ = (H-M)/(H+M)	HR₂ = (M-S)/(M+S)	HR₃ = (H-S)/(H+S)
ACIS-S	-0.691	-0.442	-0.868
ACIS-I	-0.632	-0.211	-0.744

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 EPSILON ERI, Obsid 1869

Aimpoint Quantiles 25 % 25 % Error 50 % 50 % Error 75 % 75 % Error
ACIS-S keV 0.650 7.350 0.796 0.000 0.956 0.003

Q-norm 0.045 0.955 0.064 0.000 0.085 0.000
ACIS-I keV 0.752 0.001 0.869 0.007 1.044 0.006

Q-norm 0.059 0.000 0.074 0.001 0.097 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 EPSILON ERI, Obsid 1869
Aimpoint	Quantiles	25 %	25 % Error	50 %	50 % Error	75 %	75 % Error
ACIS-S	keV	0.650	7.350	0.796	0.000	0.956	0.003
ACIS-S	Q-norm	0.045	0.955	0.064	0.000	0.085	0.000
ACIS-I	keV	0.752	0.001	0.869	0.007	1.044	0.006
ACIS-I	Q-norm	0.059	0.000	0.074	0.001	0.097	0.001