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Last modified: 11 Dec 2014

URL: http://cxc.harvard.edu/ciao/threads/aprates/

Compute Net Counts, Rate, or Flux for Point Sources

CIAO 4.9 Science Threads


Overview

Synopsis:

The tool aprates computes values and bounds for source intensity quantities (net counts, source rate, photon flux, energy flux) using counts and exposure data obtained in source and background apertures.

aprates uses Bayesian statistics to compute the background-marginalized, posterior probability distribution for source intensity, assuming non-informative prior distributions for background and source intensity (for details on the algorithm, see the Background Marginalized X-ray Source Intensity memo). The posterior distribution can be used to determine intensity value and confidence bounds or intensity upper limit.

The aprates tool is used in the srcflux script which automates the steps outlined in this thread.

Run this thread if:

You want to calculate net counts, source rate, photon flux, and/or energy flux for ACIS or HRC data.

This thread runs aprates multiple times - from computing simple net counts to computing energy fluxes with limits - each building on the previous aprates command. If you know which quantities to calculate, you can just set the appropriate parameters and run aprates once.

Related Links:

Last Update: 11 Dec 2014 - Review for CIAO 4.7. Minor edits.


Contents


srcflux

CIAO also includes a script named srcflux that can be used to simply the extraction of fluxes and count rates. It makes use of aprates as in this thread and several other tools and scripts.


Get Started

Download the sample data: 313 (ACIS-S/M31)

File types needed: regevt3, reg3, regexp3, psf3

To run this thread, you need:

  • a level=2 or level=3 event file
  • source and background region files
  • a PSF for the source and background regions
  • an exposure map

This thread uses level=3 data products which were downloaded from the the Chandra Source Catalog. CSC data is not required to run the thread. This section explains both how to download data from the CSC and how to manually create the input files.

Downloading data from the CSC

This thread uses level=3 data products which were downloaded from the the Chandra Source Catalog. These files are for the broad band (0.5-7.0 keV) of region_id=1 in ObsID 313:

acisf00313_000N001_r0001b_psf3.fits
acisf00313_000N001_r0001b_regexp3.fits
acisf00313_000N001_r0001_reg3.fits
acisf00313_000N001_r0001_regevt3.fits

To download these files:

  • Launch CSCView, the CSC GUI.

  • Search for the ObsID and region:

    From the "Standard Queries" list, select "Standard Search Criteria → Search by Observation Identification" so that it is highlighted. Then click on the "+" on the right side of the "Search Criteria" box; an o.obsid field will be added to the search criteria area. Set the value of o.obsid to "313".

    In the "Source Properties" list, expand the menus "Source Observations → Detected Source Properties → Observation-Specific Identification Information". Select "region_id" so that it is highlighted. Then click on the "+" on the right side of the "Search Criteria" box; an o.region_id field will be added to the search criteria area. Set the value of o.region_id to "1".

    Make sure there is at least one property in the "Result Set", e.g. add "Master Sources → Source Name → name".

    Click "Search". The GUI will switch to the "Results" tab and list the results returned.

  • Download the data files:

    Highlight the returned row (there should only be one, as we searched for a specific region number). In the "Data Products" list, check off these four products:

    • Source Region: Event List
    • Source Region: Exposure Map
    • Source Region: PSF
    • Source Region: Region

    Make sure the "broad [ACIS]" box is checked in the energy band section, then click "Search". The GUI will switch to the "Products" tab and list the filenames found.

    Click "Select All" to select all the files, then click "Download" to download a tarfile containing the data.


Making Source and Background Regions

This thread uses the reg3.fits file from the Chandra Source Catalog, but any FITS or ASCII region file may be used. For assistance defining and saving source and background region files, refer to the Using CIAO Region Files thread.


Making a PSF

If you choose not to download data from the CSC, you will need to make a PSF for the source and background positions before continuing.

To make a PSF, run ChaRT.


Making an Exposure Map

If you choose not to download data from the CSC, you will need to make an exposure map for the event file before continuing.

To make an exposure map, run the fluximage script, as shown in the ACIS multi-chip exposure map thread. Be sure to make an unnormalized exposure map, as shown in the thread, so that it has units of [cm^2 s]; aprates expects the input exposure values to have these units.


Syntax used in this thread

All the input to the aprates tool is obtained from the values set in the parameter file. That is, the tool doesn't read an event file or other data file to obtain the values. The input parameter values are determined by querying different data files before running aprates.

To avoid writing out many intermediate files, this thread uses a syntax with Unix pipes ("|") to use the output of one tool as the input to another without creating a physical file. For instance, this command does a calculation on the energy column with dmtcalc and then runs dmstat on the output:

unix% dmtcalc file.fits - expression="energy=1.6e-12*energy" | dmstat "-[cols energy]" verbose=0

This is equivalent to running two separate commands:

unix%  dmtcalc file.fits out.fits expression="energy=1.6e-12*energy" 
unix%  dmstat "out.fits[cols energy]" verbose=0

but the file, out.fits is never written to disk.


Displaying the Source and Background Regions

The source and background regions are stored as extensions of the reg3.fits file:

unix% dmlist acisf00313_000N001_r0001_reg3.fits blocks

--------------------------------------------------------------------------------
Dataset: acisf00313_000N001_r0001_reg3.fits
--------------------------------------------------------------------------------

     Block Name                          Type         Dimensions
--------------------------------------------------------------------------------
Block    1: PRIMARY                        Null
Block    2: SRCREG                         Table         5 cols x 1        rows
Block    3: BKGREG                         Table         5 cols x 2        rows

The ds9 command-line options are used to display them on the data, as shown in Figure 1.

unix% ds9 acisf00313_000N001_r0001_regevt3.fits -region acisf00313_000N001_r0001_reg3.fits \
      acisf00313_000N001_r0001_regevt3.fits -region "acisf00313_000N001_r0001_reg3.fits[bkgreg]" &
[Thumbnail image: Source and background regions displayed on the event file in separate ds9 frames.]

[Version: full-size]

[Print media version: Source and background regions displayed on the event file in separate ds9 frames.]

Figure 1: Regions overlaid on the image

The source region (top frame) is defined as an ellipse. The background region (bottom frame) is defined by two ellipses, the larger one excluding a smaller one to block any source counts from the background region area. Both regions are centered at (x,y)=(4164.807, 3602.933).


Net Source Counts

When the minimum number of parameters is set, aprates obtains net source counts and errors. The parameters required for this case are:

  • the number of counts in the source and background apertures: n and m
  • their geometric areas: A_s and A_b
  • their psf fractions: alpha and beta

Counts in source and background apertures

A number of different CIAO tools can be used to determine the area and number of events in apertures. These tools may yield slightly different results, depending on whether one starts with an event list or image. Results from event lists are more accurate, since event locations are typically known to finer resolution that a pixel size, and areas can be determined analytically for simple apertures. For images, aperture counts and areas are determined from those pixels whose centers fall within the aperture. We recommend the use of dmextract if an event list is available.

The number of counts in the source (n) and background (m) apertures and the areas of both apertures are found by running dmextract on the regevt3.fits file with the source and background regions. The energy range of the events is restricted to the broad band (0.5-7.0 keV):

unix%  dmextract \
       "acisf00313_000N001_r0001_regevt3.fits[energy=500:7000][bin sky=region(acisf00313_000N001_r0001_reg3.fits)]" \
       outfile=- opt=generic\
       bkg="acisf00313_000N001_r0001_regevt3.fits[energy=500:7000][bin sky=region(acisf00313_000N001_r0001_reg3.fits[bkgreg])]" |\
       dmlist -"[col counts, area,bg_counts,bg_area]" data,clean
  
#  COUNTS   AREA              BG_COUNTS   BG_AREA
   141.0    196.6885315328    9.0         4720.50

There are 141 source counts (n=141) and 9 background counts (m=9). The source area is 196.689 pixels (A_s=196.689) and the background area is 4720.50 pixels (A_b=4720.50).


PSF fractions in source and background apertures

The PSF fraction in the source (alpha) and background (beta) apertures is found by running dmstat on the psf3.fits file with the source and background regions:

unix% dmstat \
      acisf00313_000N001_r0001b_psf3.fits"[sky=region(acisf00313_000N001_r0001_reg3.fits)]" \
      centroid=no verbose=0

unix% pget dmstat out_sum
0.95296573744

unix% dmstat \
      acisf00313_000N001_r0001b_psf3.fits"[sky=region(acisf00313_000N001_r0001_reg3.fits[bkgreg])]" \
      centroid=no verbose=0

unix% pget dmstat out_sum
0.028613533096

The PSF fraction in the source aperture is 0.953 (alpha=0.953) and the PSF fraction in the background aperture is 0.029 (beta=0.029).


Run aprates to compute net counts

To summarize the parameter values that have been determined:

  • n=141
  • m=9
  • A_s=196.689
  • A_b=4720.50
  • alpha=0.953
  • beta=0.029

All the other parameters for aprates are set to a value of 1. The confidence region (conf) value is set to 90% (0.90). The output file will be named aprates_netcts.par.

The tool is run with mode=h to suppress prompting for parameter values.

unix% punlearn aprates
unix% pset aprates conf=0.90
unix% pset aprates n=141 m=9
unix% pset aprates A_s=196.689 A_b=4720.50
unix% pset aprates alpha=0.953 beta=0.029
unix% pset aprates T_s=1 E_s=1 eng_s=1 flux_s=1 T_b=1 E_b=1 eng_b=1 flux_b=1 
unix% pset aprates outfile=aprates_netcts.par

unix% aprates mode=h
# aprates (CIAO 4.4): WARNING: Large number of counts, just using Gaussian pdf

The warning indicates that Gaussian statistics were used instead of Poisson statistics; the threshold is controlled by the max_counts parameter.

The output file is in parameter file format, which makes it possible to query the output values with the tool pget:

unix% pget aprates_netcts.par src_cnts src_cnts_err_lo src_cnts_err_up
147.748
127.286
168.334

The net counts value is 147.748, and the 90% confidence region extends from 127.286 to 168.334.

The full output file, aprates_netcts.par, is included at the end of the thread. Note that while the output file contains entries for rates and fluxes, they are just the net count values repeated.


Net Count Rate

By setting the exposure times in the source (T_s) and background (T_b) apertures, the net source rate and errors will be computed.

For this example, the exposure time is the same for the source and background since they come from the same file:

unix% dmkeypar acisf00313_000N001_r0001_regevt3.fits LIVETIME echo+
5977.7355472452

The exposure time is 5977.74 s.

Since this is building on the previous run of aprates, it is only necessary to set the additional parameters and to change the output file name:

unix% pset aprates T_s=5977.74 T_b=5977.74
unix% pset aprates outfile=aprates_netrate.par

unix% aprates mode=h
# aprates (CIAO 4.4): WARNING: Large number of counts, just using Gaussian pdf

unix% pget aprates_netrate.par src_rate src_rate_err_lo src_rate_err_up
0.0247163
0.0212934
0.0281601

The net rate value is 0.0247163 ct/s, and the 90% confidence region extends from 0.0212934 to 0.0281601.

The full output file, aprates_netrate.par, is included at the end of the thread.


Net Photon Flux

By setting the average effective exposures (in cm^2-s) in the source (E_s) and background (E_b) apertures, the net photon flux and errors will be computed.

The average effective exposures is found by running dmstat on the regexp3.fits file with the source and background regions:

unix% dmstat \
      acisf00313_000N001_r0001b_regexp3.fits"[sky=region(acisf00313_000N001_r0001_reg3.fits)]" \
      centroid=no verbose=0

unix% pget dmstat out_mean
2308338.2013

unix% dmstat \
      acisf00313_000N001_r0001b_regexp3.fits"[sky=region(acisf00313_000N001_r0001_reg3.fits[bkgreg])]" \
      centroid=no verbose=0

unix% pget dmstat out_mean
2058975.0111

The average effective exposure in the source region is 2308338.2013 cm^2-s (E_s=2308338.2013) and in the background region is 2058975.0111 cm^2-s (E_b=2058975.0111).

Since this is building on the previous run of aprates, it is only necessary to set the additional parameters and to change the output file name:

unix% pset aprates E_s=2308338.2013 E_b=2058975.0111
unix% pset aprates outfile=aprates_netflux.par

unix% aprates mode=h
# aprates (CIAO 4.4): WARNING: Large number of counts, just using Gaussian pdf

unix% pget aprates_netflux.par photflux_aper photflux_aper_err_lo photflux_aper_err_up
6.398540000000001e-05
5.51211e-05
7.29037e-05

The net photon flux is 6.40e-05 photons/cm^2-sec, and the 90% confidence region extends from 5.51e-05 to 7.29e-05.

The full output file, aprates_netflux.par, is included at the end of the thread.


Net Energy Flux

There are two options for calculating the net energy flux with aprates: using the average photon energies (in ergs) or using the average of photon effective exposure (in ergs/cm^2-s).

from average photon energies

By setting the average photon energies (in ergs) in the source (eng_s) and background (eng_b) apertures, the net energy flux and errors will be computed.

The counts in the apertures are filtered from the file regevt3.fits file with the source and background regions. The energy range of the events is restricted to the broad band (0.5-7.0 keV). The event energies are first converted to ergs using dmtcalc, and the average event energies in the apertures are then computed using dmstat.

For the source aperture:

unix% dmtcalc \
      "acisf00313_000N001_r0001_regevt3.fits[energy=500:7000,sky=region(acisf00313_000N001_r0001_reg3.fits)]" \
      - expression="energy=1.6e-12*energy" | dmstat "-[cols energy]" verbose=0

unix% pget dmstat out_mean
2.5579239786e-09

For the background aperture:

unix% dmtcalc \
      "acisf00313_000N001_r0001_regevt3.fits[energy=500:7000,sky=region(acisf00313_000N001_r0001_reg3.fits[bkgreg])]" \
      - expression="energy=1.6e-12*energy" | dmstat "-[cols energy]" verbose=0

unix% pget dmstat out_mean
4.2743555979e-09

The average photon energies in the source region is 2.56e-09 ergs (eng_s=2.56e-09) and in the background region is 4.27e-09 ergs (eng_b=4.27e-09).

Note that when using this option for computing energy flux, both average exposure (E_s, E_b) and average event energy (eng_s, eng_b) must be input.

All the parameters of aprates are set to the previously-determined values. The output file is named aprates_eflux.par.

unix% punlearn aprates
unix% pset aprates conf=0.90
unix% pset aprates n=141 m=9
unix% pset aprates A_s=196.689 A_b=4720.50
unix% pset aprates alpha=0.953 beta=0.029
unix% pset aprates flux_s=1 flux_b=1 
unix% pset aprates T_s=5977.74 T_b=5977.74
unix% pset aprates E_s=2308338.2013 E_b=2058975.0111
unix% pset aprates eng_s=2.56e-09 eng_b=4.27e-09
unix% pset aprates outfile=aprates_flux.par

unix% aprates mode=h
# aprates (CIAO 4.4): WARNING: Large number of counts, just using Gaussian pdf

unix% pget aprates_flux.par flux_aper flux_aper_err_lo flux_aper_err_up
1.63475e-13
1.4078e-13
1.86309e-13

The net energy flux is 1.63e-13 ergs/cm^2-sec, and the 90% confidence region extends from 1.41e-13 to 1.86e-13.

The full output file, aprates_flux.par, is included at the end of the thread.


from average of photon effective exposure

An alternate method of computing the net energy flux and errors is to set the average of photon energy/effective exposure (in ergs/cm^2-s) in the source (flux_s) and background (flux_b) apertures.

This computation is preferable to the one using eng_s and eng_b because it more properly weights the contribution of higher energy photons, which, though few, may dominate the energy flux.

The counts in the apertures are filtered from the file regevt3.fits file with the source and background regions. The energy range of the events is restricted to the broad band (0.5-7.0 keV). The event fluxes are first computed using eff2evt, then the average of this quantity in the apertures is found with dmstat.

For the source aperture:

unix% eff2evt \
      "acisf00313_000N001_r0001_regevt3.fits[energy=500:7000][sky=region(acisf00313_000N001_r0001_reg3.fits)]" - | \
      dmstat -"[cols flux]" verbose=0

unix% pget dmstat out_mean
9.8048216059e-16

For the background aperture:

unix% eff2evt \
      "acisf00313_000N001_r0001_regevt3.fits[energy=500:7000][sky=region(acisf00313_000N001_r0001_reg3.fits[bkgreg])]" - | \
      dmstat -"[cols flux]" verbose=0

unix% pget dmstat out_mean
2.2342449512e-15

The average of photon energy/effective exposure in the source region is 9.80e-16 ergs/cm^2-s (flux_s=9.80e-16) and in the background region is 2.23e-15 (flux_b=2.23e-15).

All the parameters of aprates are set to the previously-determined values. The output file is named aprates_eflux.par.

unix% punlearn aprates
unix% pset aprates conf=0.90
unix% pset aprates n=141 m=9
unix% pset aprates A_s=196.689 A_b=4720.50
unix% pset aprates alpha=0.953 beta=0.029
unix% pset aprates T_s=5977.74 T_b=5977.74
unix% pset aprates E_s=2308338.2013 E_b=2058975.0111
unix% pset aprates eng_s=1 eng_b=1
unix% pset aprates flux_s=9.80e-16 flux_b=2.23e-15
unix% pset aprates outfile=aprates_eflux.par

unix% aprates mode=h
# aprates (CIAO 4.4): WARNING: Large number of counts, just using Gaussian pdf

unix% pget aprates_eflux.par eflux_aper eflux_aper_err_lo eflux_aper_err_up
1.44448e-13
1.24371e-13
1.64648e-13

The net energy flux is 1.44e-13 ergs/cm^2-sec, and the 90% confidence region extends from 1.24e-13 to 1.65e-13.

The full output file, aprates_eflux.par, is included at the end of the thread.



Parameters for /home/username/cxcds_param/aprates_netcts.par



Parameters for aprates_netcts.par

     (src_cnts = 147.748)
(src_cnts_err_lo = 127.286)
(src_cnts_err_up = 168.334)
(src_cnts_conf = 0.900024)
(src_cnts_status = 0)
(src_cnts_signif = 11.8161)
(src_cnts_mode = 147.748)
     (src_rate = 147.748)
(src_rate_err_lo = 127.286)
(src_rate_err_up = 168.334)
(src_rate_conf = 0.900024)
(src_rate_status = 0)
(src_rate_signif = 11.8161)
(src_rate_mode = 147.748)
(photflux_aper = 147.748)
(photflux_aper_err_lo = 127.286)
(photflux_aper_err_up = 168.334)
(photflux_aper_conf = 0.900024)
(photflux_aper_status = 0)
(photflux_aper_signif = 11.8161)
(photflux_aper_mode = 147.748)
    (flux_aper = 147.748)
(flux_aper_err_lo = 127.286)
(flux_aper_err_up = 168.334)
(flux_aper_conf = 0.900024)
(flux_aper_status = 0)
(flux_aper_signif = 11.8161)
(flux_aper_mode = 147.748)
   (eflux_aper = 147.748)
(eflux_aper_err_lo = 127.286)
(eflux_aper_err_up = 168.334)
(eflux_aper_conf = 0.900024)
(eflux_aper_status = 0)
(eflux_aper_signif = 11.8161)
(eflux_aper_mode = 147.748)
           (_n = 141)
         (_A_s = 196.689)
       (_alpha = 0.953)
         (_T_s = 1)
         (_E_s = 1)
       (_eng_s = 1)
      (_flux_s = 1)
           (_m = 9)
         (_A_b = 4720.5)
        (_beta = 0.029)
         (_T_b = 1)
         (_E_b = 1)
       (_eng_b = 1)
      (_flux_b = 1)
         (mode = ql)

    


Parameters for /home/username/cxcds_param/aprates_netrate.par



Parameters for aprates_netrate.par

     (src_cnts = 147.748)
(src_cnts_err_lo = 127.286)
(src_cnts_err_up = 168.334)
(src_cnts_conf = 0.900024)
(src_cnts_status = 0)
(src_cnts_signif = 11.8161)
(src_cnts_mode = 147.748)
     (src_rate = 0.0247163)
(src_rate_err_lo = 0.0212934)
(src_rate_err_up = 0.0281601)
(src_rate_conf = 0.900024)
(src_rate_status = 0)
(src_rate_signif = 11.8161)
(src_rate_mode = 0.0247163)
(photflux_aper = 147.748)
(photflux_aper_err_lo = 127.286)
(photflux_aper_err_up = 168.334)
(photflux_aper_conf = 0.900024)
(photflux_aper_status = 0)
(photflux_aper_signif = 11.8161)
(photflux_aper_mode = 147.748)
    (flux_aper = 147.748)
(flux_aper_err_lo = 127.286)
(flux_aper_err_up = 168.334)
(flux_aper_conf = 0.900024)
(flux_aper_status = 0)
(flux_aper_signif = 11.8161)
(flux_aper_mode = 147.748)
   (eflux_aper = 147.748)
(eflux_aper_err_lo = 127.286)
(eflux_aper_err_up = 168.334)
(eflux_aper_conf = 0.900024)
(eflux_aper_status = 0)
(eflux_aper_signif = 11.8161)
(eflux_aper_mode = 147.748)
           (_n = 141)
         (_A_s = 196.689)
       (_alpha = 0.953)
         (_T_s = 5977.74)
         (_E_s = 1)
       (_eng_s = 1)
      (_flux_s = 1)
           (_m = 9)
         (_A_b = 4720.5)
        (_beta = 0.029)
         (_T_b = 5977.74)
         (_E_b = 1)
       (_eng_b = 1)
      (_flux_b = 1)
         (mode = ql)

    


Parameters for /home/username/cxcds_param/aprates_netflux.par



Parameters for aprates_netflux.par

     (src_cnts = 147.748)
(src_cnts_err_lo = 127.286)
(src_cnts_err_up = 168.334)
(src_cnts_conf = 0.900024)
(src_cnts_status = 0)
(src_cnts_signif = 11.8161)
(src_cnts_mode = 147.748)
     (src_rate = 0.0247163)
(src_rate_err_lo = 0.0212934)
(src_rate_err_up = 0.0281601)
(src_rate_conf = 0.900024)
(src_rate_status = 0)
(src_rate_signif = 11.8161)
(src_rate_mode = 0.0247163)
(photflux_aper = 6.39854e-05)
(photflux_aper_err_lo = 5.51211e-05)
(photflux_aper_err_up = 7.29037e-05)
(photflux_aper_conf = 0.900024)
(photflux_aper_status = 0)
(photflux_aper_signif = 11.8121)
(photflux_aper_mode = 6.39854e-05)
    (flux_aper = 6.39854e-05)
(flux_aper_err_lo = 5.51211e-05)
(flux_aper_err_up = 7.29037e-05)
(flux_aper_conf = 0.900024)
(flux_aper_status = 0)
(flux_aper_signif = 11.8121)
(flux_aper_mode = 6.39854e-05)
   (eflux_aper = 147.748)
(eflux_aper_err_lo = 127.286)
(eflux_aper_err_up = 168.334)
(eflux_aper_conf = 0.900024)
(eflux_aper_status = 0)
(eflux_aper_signif = 11.8161)
(eflux_aper_mode = 147.748)
           (_n = 141)
         (_A_s = 196.689)
       (_alpha = 0.953)
         (_T_s = 5977.74)
         (_E_s = 2.30834e+06)
       (_eng_s = 1)
      (_flux_s = 1)
           (_m = 9)
         (_A_b = 4720.5)
        (_beta = 0.029)
         (_T_b = 5977.74)
         (_E_b = 2.05898e+06)
       (_eng_b = 1)
      (_flux_b = 1)
         (mode = ql)

    


Parameters for /home/username/cxcds_param/aprates_flux.par



Parameters for aprates_flux.par

     (src_cnts = 147.748)
(src_cnts_err_lo = 127.286)
(src_cnts_err_up = 168.334)
(src_cnts_conf = 0.900024)
(src_cnts_status = 0)
(src_cnts_signif = 11.8161)
(src_cnts_mode = 147.748)
     (src_rate = 0.0247163)
(src_rate_err_lo = 0.0212934)
(src_rate_err_up = 0.0281601)
(src_rate_conf = 0.900024)
(src_rate_status = 0)
(src_rate_signif = 11.8161)
(src_rate_mode = 0.0247163)
(photflux_aper = 6.39854e-05)
(photflux_aper_err_lo = 5.51211e-05)
(photflux_aper_err_up = 7.29037e-05)
(photflux_aper_conf = 0.900024)
(photflux_aper_status = 0)
(photflux_aper_signif = 11.8121)
(photflux_aper_mode = 6.39854e-05)
    (flux_aper = 1.63475e-13)
(flux_aper_err_lo = 1.4078e-13)
(flux_aper_err_up = 1.86309e-13)
(flux_aper_conf = 0.900024)
(flux_aper_status = 0)
(flux_aper_signif = 11.7871)
(flux_aper_mode = 1.63475e-13)
   (eflux_aper = 147.748)
(eflux_aper_err_lo = 127.286)
(eflux_aper_err_up = 168.334)
(eflux_aper_conf = 0.900024)
(eflux_aper_status = 0)
(eflux_aper_signif = 11.8161)
(eflux_aper_mode = 147.748)
           (_n = 141)
         (_A_s = 196.689)
       (_alpha = 0.953)
         (_T_s = 5977.74)
         (_E_s = 2.30834e+06)
       (_eng_s = 2.56e-09)
      (_flux_s = 1)
           (_m = 9)
         (_A_b = 4720.5)
        (_beta = 0.029)
         (_T_b = 5977.74)
         (_E_b = 2.05898e+06)
       (_eng_b = 4.27e-09)
      (_flux_b = 1)
         (mode = ql)

    


Parameters for /home/username/cxcds_param/aprates_eflux.par



Parameters for aprates_eflux.par

     (src_cnts = 147.748)
(src_cnts_err_lo = 127.286)
(src_cnts_err_up = 168.334)
(src_cnts_conf = 0.900024)
(src_cnts_status = 0)
(src_cnts_signif = 11.8161)
(src_cnts_mode = 147.748)
     (src_rate = 0.0247163)
(src_rate_err_lo = 0.0212934)
(src_rate_err_up = 0.0281601)
(src_rate_conf = 0.900024)
(src_rate_status = 0)
(src_rate_signif = 11.8161)
(src_rate_mode = 0.0247163)
(photflux_aper = 6.39854e-05)
(photflux_aper_err_lo = 5.51211e-05)
(photflux_aper_err_up = 7.29037e-05)
(photflux_aper_conf = 0.900024)
(photflux_aper_status = 0)
(photflux_aper_signif = 11.8121)
(photflux_aper_mode = 6.39854e-05)
    (flux_aper = 6.39854e-05)
(flux_aper_err_lo = 5.51211e-05)
(flux_aper_err_up = 7.29037e-05)
(flux_aper_conf = 0.900024)
(flux_aper_status = 0)
(flux_aper_signif = 11.8121)
(flux_aper_mode = 6.39854e-05)
   (eflux_aper = 1.44448e-13)
(eflux_aper_err_lo = 1.24371e-13)
(eflux_aper_err_up = 1.64648e-13)
(eflux_aper_conf = 0.900024)
(eflux_aper_status = 0)
(eflux_aper_signif = 11.7733)
(eflux_aper_mode = 1.44448e-13)
           (_n = 141)
         (_A_s = 196.689)
       (_alpha = 0.953)
         (_T_s = 5977.74)
         (_E_s = 2.30834e+06)
       (_eng_s = 1)
      (_flux_s = 9.80e-16)
           (_m = 9)
         (_A_b = 4720.5)
        (_beta = 0.029)
         (_T_b = 5977.74)
         (_E_b = 2.05898e+06)
       (_eng_b = 1)
      (_flux_b = 2.23e-15)
         (mode = ql)

    

History

15 Dec 2008 New for CIAO 4.1
01 Jul 2009 added instructions on download the data from the CSC
27 Jul 2009 Bayesian statistics information added to the Overview
09 Feb 2010 updated for CIAO 4.2: minor changes to screen output
23 Feb 2010 eff2evt can handle file filters, so the dmcopy steps and temporary files aren't necessary (In "Net Energy Flux: from average of photon effective exposure" section)
09 Mar 2010 added a link to the Chandra Source Catalog, which contains reference fluxes for many sources
07 Jun 2010 use dmextract to get counts in source and background apertures; minor related adjustments to screen output
15 Dec 2010 reviewed for CIAO 4.3: no changes
28 Jan 2011 confidence limits are calculated for 90% instead of 68% (the aprates default)
28 Feb 2011 clarified that any region file may be used to run the thread
28 Apr 2011 further clarified that Chandra Source Catalog data is not required to run the thread
09 Jun 2011 removed duplicate pset commands; calculated values were not affected
17 Aug 2011 updated download instructions to match current CSCView interface
26 Oct 2011 added "opt=generic" to the dmextract command to avoid a warning from the tool ("WARNING: ignoring opt=pha1: extracting radial profile from sky column.").
09 Jan 2012 reviewed for CIAO 4.4: added missing line to final aprates example (pset aprates eng_s=1 eng_b=1)
03 Dec 2012 Review for CIAO 4.5; no changes
25 Dec 2013 Review for CIAO 4.6. Added link to new srcflux script. Additional edits are likely.
11 Dec 2014 Review for CIAO 4.7. Minor edits.


Last modified: 11 Dec 2014
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