ChaMP Initial Data Release

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Дата индексирования: Tue Oct 2 07:31:01 2012
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ChaMP Initial Data Release - X-ray

ChaMP X-ray Data Products

ChaMP XPIPE products

Images

There are jpeg images of the full field in broad band (B) and of individual chips in each band. The file names are of the format

         OBSID{obsid}_ccdid{ccdid}_{energyband}_ext.jpg

         eg., OBSID00914_ccdid0_B_ext.jpg

"ext" indicates that circles plotted in the figure are used for count extraction (i.e., 95% encircled energy)

There are smoothed broad band images of each chip in FITS format.

Source properties table

The source properties table has the following columns:

champ name : Source ID in the format explained in the Definitions section.
ra : RA in decimal degrees. (J2000)
dec : Dec in decimal degrees. (J2000)
pos_error : Source count extraction radius in arcseconds.
netB : net counts in B-band. See Definitions section.
error_netB : error of net counts in B-band. see Definitions section.
netS : S-band net counts, defined analogously to netB.
netH : H-band net counts, defined analogously to netB.
netS1 : S1-band net counts, defined analogously to netB.
netS2 : S2-band net counts, defined analogously to netB.
HR : Hardness Ratio. See Definitions section.
C21 : X-ray color. See Definitions section.
C32 : X-ray color. See Definitions section.
rateB : B-band count rate in ksec. See Definitions section.
mean_ea : Mean effective area.
nearbysrc : Number of other sources in the source extraction circle.

Background light curve

Plots of count rate vs time for each chip. The average count rate and 3-sigma limits are marked. Points which fall outside the 3-sigma limits are marked by red crosses. The blue line segments at the bottom show the Good Time Interval (GTI).

X-ray colors

A color-color plot for sources with more than 50 counts. A grid is overlaid for reference, showing expected positions on the plot for various power-law spectra and absorbing column densities.

Definitions


  srcid = XS{obsid}{energyband}{ccdid}_srcno 
     eg., XS12345B9_001

  energy band:
        B  : 0.3 - 8.0 keV
        S  : 0.3 - 2.5 keV
        S1 : 0.3 - 0.9 keV
        S2 : 0.9 - 2.5 keV
        H  : 2.5 - 8.0 keV

        HR  = H-S / H+S
        C21 = -logS2+logS1 
        C32 = -logH+logS2

   netB       = srcB - bkgB * barea_ratio
   error_netB = [ (1.0+sqrt(srcB +0.75))^2 + ((1.0+sqrt(bkgB+0.75))/barea_ratio)^2 ]^0.5

   SNR = netB/error_netB

   rateB       = 1000.0 * neB        / exposure * [max_ea / mean_ea]    [exposure and max_ea from "xfield_exposure"]
   error_rateB = 1000.0 * error_netB / exposure * [max_ea / mean_ea]
      (max_ea = maximum effective area for a given CCD)
      (mean_ea = mean effective area within the source extraction radius determined from an exposure map)
 
   HR       = netH-netS / netH+netS
   error_HR = (4.0 / netB**4 * (netS**2 * error_netH**2 + netH**2 * error_netS**2))**0.5

   C21       = -log(netS2)+log(netS1)
   error_C21 = ((1.0/netS1/2.302585*error_netS1)**2 +  (1.0/netS2/2.302585*error_netS2)**2)**0.5

   C32       = -log(netH)+log(netS2)
   error_C32 = ((1.0/netS2/2.302585*error_netS2)**2 +  (1.0/netH/2.302585*error_netH)**2)**0.5