Target Preview

Observation ID Observation Date Target Star Name Object Class Spectral Type B-V Magnitude RA (deg) DEC (deg) Exposure (s)
1927 2001-02-07 09:57:17 VELA X-1 GP Vel High Mass X-ray Binary B0Ia 0.3750 135.528360 -40.554810 29430.47

Chandra Configuration for the Observation

Zeroth-Order Image

Image File Missing: Snapshot of the Zeroth-Order Image
Zeroth-Order Events Zeroth-Order Count Rate (cts/s) Pileup
21632 0.7350 severe
The zeroth-order image for VELA X-1

Hardness Ratios and Quantiles

Hardness ratios and quantiles are calculated from the predicted ACIS-S or ACIS-I aimpoint spectra, as indicated.
Hardness Ratios
Aimpoint HR1 = (H-M)/(H+M) HR2 = (M-S)/(M+S) HR3 = (H-S)/(H+S)
ACIS-S 0.930 0.696 0.987
ACIS-I 0.943 0.734 0.991
S, M, and H represent the predicted total counts in the following passbands:
S: 0.3-0.9 keV
M: 0.9-1.5 keV
H: 1.5-8.0 keV
Quantiles
Aimpoint Quantiles 25 % 25 % Error 50 % 50 % Error 75 % 75 % Error
ACIS-S keV 3.701 0.003 4.694 0.000 5.716 0.001
Q-norm 0.442 0.000 0.571 0.000 0.703 0.000
ACIS-I keV 3.818 0.001 4.811 0.002 5.833 0.006
Q-norm 0.457 0.000 0.586 0.000 0.719 0.001
Normalized quantiles (Q-norm) are defined as:
Qx = (Ex - Elo)/(Ehi - Elo)
Where Elo = 0.3 keV and Ehi = 8.0 keV.
Hardness Ratio plots and Quantile-based Color-Color DiagramsX-Atlas Hardness Ratios and Quantiles Listing

Spectral Metrics

A series of line-line, line-continuum, and continuum-continuum ratios calculated from the high-resolution 1st order MEG or LEG spectrum.
Line-Line Ratios
Ne X / O VIII Ne2O Error O VII(i) / O VII(f) Oif Error O VII(r) / O VIII O78 Error O VIII / Fe XVII O8Fe Error Mg XII / Fe XVII Mg2Fe Error Si XIV / Fe XVII Si2Fe Error S XV / Fe XVII S2Fe Error

short line / cont
Line-Continuum & Continuum-Continuum Ratios
sl2c Error long line / cont ll2c Error line / cont l2c Error cont long / cont short cl2cs Error cont long / cont med cl2cm Error cont med / cont short cm2cs Error
X-Atlas Spectral Metrics Listing

Spectral Fits

Image File Missing: 2T xsmekal zeroth-order fit
Mewe-Kaastra-Liedahl 2-temperature fit of the low-resolution zeroth-order spectrum of VELA X-1.
Warning: The zeroth-order spectrum may be subject to distortions from pileup.

Image File Missing: 2T xsmekal ACIS-S fit
Mewe-Kaastra-Liedahl 2-temperature fit of the predicted low-resolution ACIS-S Aimpoint spectrum of VELA X-1. The predicted spectrum was scaled to 1500 counts.

Image File Missing: 2T xsmekal ACIS-I fit
Mewe-Kaastra-Liedahl 2-temperature fit of the predicted low-resolution ACIS-I Aimpoint spectrum of VELA X-1. The predicted spectrum was scaled to 1500 counts.

Aimpoint Model nH (1022/cm3) nH error kT (keV) kT error kT2 (keV) kT2 error Abundance (solar) Abundance error Flux (ergs/cm2/s) Flux Emission Ratio (kT2/kT1) Reduced Chi2 DoF
zeroth-order xswabs*(xsmekal1+xsmekal2) 10.000 30.000 0.010 1.93 3.98369e-11 0 9.77 377
ACIS-S xswabs*(xsmekal1+xsmekal2) 0.010 30.000 1.000 1.49 9.16679e-14 0 15.42 83
ACIS-I xswabs*(xsmekal1+xsmekal2) 0.010 30.000 1.000 1.50 1.19688e-13 0 15.12 83
X-Atlas Spectral Fits Listing

HETG Light Curve

Image File Missing: HETG Light Curve
GLvary
Odds9999.999
Prob.1.000
Var. Index10
HETG light curve for VELA X-1, constructed from all ±1st, ±2nd, and ±3rd order HETG events.

HETG HEG Spectrum

Image File Missing: High-Resolution 1st Order HEG spectrum of obsid 1927
High-Resolution 1st Order HEG Spectrum for VELA X-1

HETG MEG Spectrum

Image File Missing: High-Resolution 1st Order MEG Spectrum of obsid 1927
High-Resolution 1st Order MEG Spectrum for VELA X-1

X-Atlas Data Products

Spectral Data
PHA II HEG ±1st Order PHA HEG ±1st Order gARF MEG ±1st Order PHA MEG ±1st Order gARF [Counts/s/Å] FITS [Counts/s/Å] text [ph/s/Å/cm2] FITS [ph/s/Å/cm2] text
Standard Data Products (Cycle 06)
Aimpoint ARFAimpoint RMF
ACIS-SACIS-IACIS-SACIS-I
Retrieve observation data from the Chandra Data Archive: WebChaSeR
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