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Last modified: 17 Dec 2014

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

Multiple Chip ACIS Exposure Map and Exposure-corrected Image

CIAO 4.7 Science Threads


Overview

Synopsis:

mkexpmap generates an exposure map which may be used to convert a counts image of a source to an image in flux units. The computed exposure map is essentially an image of the effective area at each sky position, accounting for the effects of dither motion which are especially important near the edges of the detector. The fluximage script automates the creation of an exposure-corrected image for a Chandra observation.

Purpose:

To build an exposure map for an entire ACIS chip array, create an exposue-corrected image, and find an approximation for the source flux.

If only one chip is being used, follow the ACIS Exposure Map (Single Chip) and Exposure-corrected Image thread.

Related Links:

Last Update: 17 Dec 2014 - Reviewed for CIAO 4.7; minor edits only.


Contents


Get Started

Download the sample data: 11823 (ACIS-I, RCW 103)

unix% cd 11823
unix% punlearn chandra_repro
unix% chandra_repro mode=h

Using the fluximage Script

How fluximage works

When running fluximage, you are only required to provide an input event file. The script will read the related data product filenames - bad pixels, aspect solution, mask (ACIS), and dead time correction (HRC) - and look for them in the working directory. If the files are in a different location or you wish to be explicit in what files are used, all of the input filenames may be set in the parameter file.

The fluximage script runs the following tools:

  • dmcopy: to create an event image at with the specified binning factor
  • hrc_bkgrnd_lookup, reproject_events, and dmimgcalc: to subtract the particle background (HRC-I only)
  • asphist: to build the aspect histogram(s)
  • mkinstmap: to calculate the instrument map(s) for the center of each energy band
  • mkexpmap: to calculate the exposure map(s) in each energy band
  • dmimgcalc: to combine the exposure maps (multi-chip/plate case only)
  • dmimgthresh: to make a "threshold cut" before dividing the image by the exposure map, removing the hot pixels at the edges (optional)
  • dmimgcalc: to normalize the image by the exposure map

For the multi-chip ACIS or multi-plate HRC-S cases, the tools are run once per chip or plate and are then combined into an image of the full detector.

By default, the intermediate per-chip data products are removed after the script has completed running. To save these (potentially numerous) files, set the cleanup parameter to no.


Run the script

In this example, the script is run for all chips in an ACIS-I observation. The input event file is provided, and the supporting data filenames are read from the header. We use the default bin size (which is 8 for ACIS and 32 for HRC data).

The energy range is restricted from 0.5 keV to 7 keV, and a center-band energy of 2.3 keV is used. This corresponds to the Chandra Source Catalog broad band, so we can set the bands parameter as bands=0.5:7.0:2.3 or bands=broad (which is the default value).

unix% punlearn fluximage
unix% fluximage repro/ flux/
Running fluximage
Version: 13 December 2013

Found repro/acisf11823_repro_evt2.fits
Using event file repro/acisf11823_repro_evt2.fits
Using CSC ACIS broad science energy band.
Aspect solution repro/pcadf391758163N002_asol1.fits found.
Bad-pixel file repro/acisf11823_repro_bpix1.fits found.
Mask file repro/acisf11823_001N002_msk1.fits found.

The output images will have 297 by 297 pixels, pixel size of 3.936 arcsec,
    and cover x=2912.5:5288.5:8,y=2824.5:5200.5:8.

Running tasks in parallel with 4 processors.
Creating aspect histograms for obsid 11823
Creating 4 instrument maps for obsid 11823
Creating 4 exposure maps for obsid 11823
Combining 4 exposure maps for obsid 11823
Thresholding data for obsid 11823
Exposure-correcting image for obsid 11823

The following files were created:

 The clipped counts image is:
     flux/broad_thresh.img

 The clipped exposure map is:
     flux/broad_thresh.expmap

 The exposure-corrected image is:
     flux/broad_flux.img

Note that the script looked in the repro/ directory for any file matching the pattern "*evt*", finding repro/acisf11823_repro_evt2.fits. You can check the parameter file that was used with plist fluximage.


WARNING about creating a large image

If the chosen binning factor is small enough (e.g. binsize=1 for an ACIS-I observation) then the following warning will be seen:

# DMCOPY (CIAO): WARNING: Creating large image: 84 MB. Current max set at 50 MB.
Increase maximum using [opt mem=n] or increase blocking to reduce size.

The output files are completely valid; the warning is just there to let you know that the files that are being created are large. At present there is no way to hide this message.


Creating a three-color image

Here we use fluximage to calculate the exposure-corrected images in three bands; in this case the soft, medium, and hard bands defined in the Chandra Source Catalog (for which the shortcut bands=csc can be used):

unix% fluximage repro/ flux/ bands=csc
Running fluximage
Version: 13 December 2013

Found repro/acisf11823_repro_evt2.fits
Using event file repro/acisf11823_repro_evt2.fits
Using CSC ACIS soft science energy band.
Using CSC ACIS medium science energy band.
Using CSC ACIS hard science energy band.
Aspect solution repro/pcadf391758163N002_asol1.fits found.
Bad-pixel file repro/acisf11823_repro_bpix1.fits found.
Mask file repro/acisf11823_001N002_msk1.fits found.

The output images will have 297 by 297 pixels, pixel size of 3.936 arcsec,
    and cover x=2912.5:5288.5:8,y=2824.5:5200.5:8.

Running tasks in parallel with 4 processors.
Creating aspect histograms for obsid 11823
Creating 12 instrument maps for obsid 11823
Creating 12 exposure maps for obsid 11823
Combining 4 exposure maps for 3 bands (obsid 11823)
Thresholding data for obsid 11823
Exposure-correcting 3 images for obsid

The following files were created:

 The clipped counts images are:
     flux/soft_thresh.img
     flux/medium_thresh.img
     flux/hard_thresh.img

 The clipped exposure maps are:
     flux/soft_thresh.expmap
     flux/medium_thresh.expmap
     flux/hard_thresh.expmap

 The exposure-corrected images are:
     flux/soft_flux.img
     flux/medium_flux.img
     flux/hard_flux.img

and display the image in ds9 (Figure 1).

[Thumbnail image: The central source is blue whilst the diffuse emission around it is an orange/brown mixture.]

[Version: full-size]

[Print media version: The central source is blue whilst the diffuse emission around it is an orange/brown mixture.]

Figure 1: Three-color image (exposure corrected) of RCW 103

unix% ds9 -rgb -red soft_flux.img -green medium_flux.img -blue hard_flux.img \
         -rgb lock scale yes -scale mode 99.5 -zoom 2

The image can be compared to that obtained using two observations of RCW 103.

The choice of the CSC soft, medium, and hard bands for this image was made for didactic reasons. Other choices may make more sense for your science goals.

Now proceed to the Calculate the Source Flux section, using the exposure-corrected image (here, flux/broad_flux.img).


Step-by-Step Guide

Please ensure that you have set up ardlib to use the bad pixel file for your observation before following this thread.

In this example, the energy range was restricted from 0.5 keV to 7 keV:

unix% dmcopy "acisf11823_repro_evt2.fits[energy=500:7000]" 11823.evt2

Note: do not use the energy-filtered file (11823.evt2 in this case) to extract spectra (e.g. as input to specextract); instead use the original file.

1. Syntax note: foreach

This thread uses "foreach" loops to run the same CIAO tool for multiple chips. The syntax is correct for the csh or tcsh shell. If you are using another shell, e.g. bash, change the loop syntax accordingly.


2. Create An Image

First, we need to create the image which will ultimately be normalized by the exposure map. Here we decided to block the image by a factor of 8:

unix% dmcopy "11823.evt2[sky=region(acisf11823_001N002_fov1.fits)][bin sky=8]" 11823.i0123.img
unix% get_sky_limits 11823.i0123.img 
Running: get_sky_limits
  version: 12 September 2012
Checking binning of image: 11823.i0123.img
  Image has 297 x 297 pixels
  Pixel size is 8.0 by 8.0
  Lower left (0.5,0.5) corner is x,y= 2916.7, 2824.8
  Upper right (297.5,297.5) corner is x,y= 5292.7, 5200.8
  DM filter is:
    x=2916.7:5292.7:#297,y=2824.8:5200.8:#297
  mkexpmap xygrid value is:
    2916.7:5292.7:#297,2824.8:5200.8:#297

This uses the information in the FOV file to limit the sky area of the image to that covered by the observation. See the chip region FAQ for more ways of finding the chip boundaries.


3. Compute Exposure Map

Check Which Chips Are On

The list of chips used in the observation is stored in the DETNAM keyword of the event file:

unix% dmkeypar 11823.evt2 detnam echo+
ACIS-0123

A description of the layout of the ACIS focal plane can be found in The Chandra Proposers' Observatory Guide.

What is the spectrum of the source?

We selected a region around the central source, using ds9, and saved it as obj.reg:

unix% cat obj.reg
# Region file format: CIAO version 1.0
circle(4181.5,3941.5,8)

We can use this file to extract a spectrum of the object in energy space and find the peak energy.

First, we use the CIAO tool dmextract to create a histogram of count-rate as a function of energy. Since we are not binning on pi or pha, we set opt=generic, and we use a bin size of 50 eV to improve the signal to noise:

unix% punlearn dmextract
unix% pset dmextract opt=generic
unix% dmextract "11823.evt2[sky=region(obj.reg)][bin energy=500:7000:50]" 11823.energy.fits

The dmstat tool is used to find the maximum count from the histogram, followed by dmlist to locate the corresponding energy:

unix% dmstat "11823.energy.fits[cols counts]" sigma-
COUNTS[count]
    min:	1 	      @:	3
    max:	265 	      @:	25
   mean:	69.446153846
    sum:	9028
   good:	130
   null:	0

unix% dmlist "11823.energy.fits[counts>250][cols energy,counts]" data,clean
#  ENERGY               COUNTS
               1675.0        254
               1725.0        265
               1775.0        260

For this dataset, the peak of the measured spectrum is ~1.7 keV (which is expected since this is close to the peak of the ACIS effective area). Using the peak value would mean that we would be under-estimating the flux if the energy band is too broad; see the discussion of band selection in the Chandra Source Catalog for more information. So we will use the 2.3 keV used by the CSC, but note that this is something that depends on the spectrum of the source (or sources) being analysed.

[There is a strong peak aroung 1.7 keV, with few counts below 1 keV and a longer tail at higher energies.]

[Version: postscript, PDF]

[Print media version: There is a strong peak aroung 1.7 keV, with few counts below 1 keV and a longer tail at higher energies.]

Figure 2: Energy spectrum of the central source in RCW 103

The two vertical lines indicate the 1.7 keV peak and the 2.3 keV value defined by the Chandra Source Catalog for its "broad" band.

Compute the Aspect Histograms

With the aspect solution file we can create a binned histogram for each chip, detailing the aspect history of the observation.

The binning used by the asphist tool is controlled by its res_xy parameter. The default value of 0.5 arcsec was chosen to match the high-resolution capabilities of Chandra. Since we are creating images - and therefore exposure maps - at a binning significantly larger than the natural pixel scale of ACIS, we can increase the res_xy parameter and so reduce the time it takes to run mkexpmap. To ensure that aliasing is not significant, we chose the resolution to be half the pixel size; that is 1.9 arcseconds (rounding down from 4 * 0.492 = 1.968).

In some cases there will be more than one aspect solution file (pcadXXX_asol1.fits) for an observation. All the files must be input, either as a list or as a stack. If you used chandra_repro to re-process the data then it has created a stack file for you, called acisf<obsid>_asol1.lis, which we use in this case (although as we only have a single aspect solution we could also have just used it directly):

unix% cat acisf11823_asol1.lis 
/data/ciao/11823/primary/pcadf391758163N002_asol1.fits
unix% punlearn asphist
unix% pset asphist infile=@acisf11823_asol1.lis
unix% pset asphist res_xy=1.9 mode=h
unix% foreach d ( 0 1 2 3 )
foreach? asphist outfile=${d}.asphist evtfile="11823.evt2[ccd_id=${d}]"
foreach? end

Calculate the Instrument Maps

Since the mirror effective area is used to create the instrument map, and that area is energy dependent, it is necessary to decide at what energy to perform the calculation (or whether to use a spectrum as weights). In this example we are going to assume a monoenergetic distribution of source photons of 2.3 keV (monoenergy parameter). The Calculating Spectral Weights for mkinstmap thread shows how to create a weighted instrument map using mkinstmap.

Note that it is not necessary for the instrument map to be congruent with the exposure map; the instrument map should describe the chip with full resolution.

At this point make sure that you have set up ardlib to use the bad pixel file for your observation. For example, checking the setting for ACIS-I3 we get:

unix% pget ardlib AXAF_ACIS3_BADPIX_FILE
/data/ciao/11823/repro/acisf11823_001N002_bpix1.fits[BADPIX3]

where we are using the bad-pixel file created by chandra_repro for this observation.

unix% punlearn mkinstmap
unix% pset mkinstmap pixelgrid="1:1024:#1024,1:1024:#1024"
unix% pset mkinstmap obsfile=11823.evt2 
unix% pset mkinstmap maskfile=acisf11823_001N002_msk1.fits
unix% pset mkinstmap monoenergy=2.3 mode=h

The monoenergy parameter value may be different for your science objectives.

Including the maskfile parameter is particularly important if you are interested in having an accurate exposure map at the very edge of a CCD, subarray or window. The pixelgrid parameter should not be changed for the case of a subarray or window; the mask file will account for the detector range being different. For more information, see the dictionary entry on mask files.

The pbkfile parameter has been deprecated and should be left empty; more details can be found on the Watchout page. The obsfile parameter should use the event file rather than the aspect histogram, as used in previous versions of CIAO.

Now run the tool once for each chip:

unix% foreach d ( 0 1 2 3 )
foreach? mkinstmap detsubsys=ACIS-${d} outfile=${d}.instmap
foreach? end

Calculate the Exposure Maps

Now we use mkexpmap and the aspect information stored in the histogram to project the instrument map onto the sky. We need to set the xygrid parameter to produce an exposure map that is the same size as the image created from the event list. The get_sky_limits script can be used to easily calculate this information from the existing image:

unix% get_sky_limits 11823.i0123.img 
Running: get_sky_limits
  version: 12 September 2012
Checking binning of image: 11823.i0123.img
  Image has 297 x 297 pixels
  Pixel size is 8.0 by 8.0
  Lower left (0.5,0.5) corner is x,y= 2916.7, 2824.8
  Upper right (297.5,297.5) corner is x,y= 5292.7, 5200.8
  DM filter is:
    x=2916.7:5292.7:#297,y=2824.8:5200.8:#297
  mkexpmap xygrid value is:
    2916.7:5292.7:#297,2824.8:5200.8:#297

You can then set the xygrid parameter using the information provided by the script, either manually or via

unix% pset mkexpmap xygrid=")get_sky_limits.xygrid"

(if the latter, do not run get_sky_limits again until after running mkexmap).

Note: If you are computing a low-resolution exposure map and speed is more important than accuracy, set useavgaspect=yes. In doing so, only the average aspect pointing will be used to derive the exposure map; otherwise all points in the aspect histogram will be used. The time required to compute the exposure map is proportional to the number of bins in the aspect histogram; if the aspect histogram contains 100 bins, then the use of this option reduces the run time by a factor of 100, approximately (you may also want to set verbose to 2, since this causes mkexpmap to output percentage-completed information). Using the full aspect solution will help accurately account for chip edges, bad pixels, etc.

unix% set xygrid = `pget get_sky_limits xygrid`
unix% echo $xygrid
2916.7:5292.7:#297,2824.8:5200.8:#297
unix% punlearn mkexpmap
unix% pset mkexpmap xygrid=$xygrid normalize=no mode=h
unix% foreach d ( 0 1 2 3 )
foreach? mkexpmap instmapfile=${d}.instmap \
                  outfile=${d}.bin8.expmap \
                  asphistfile=${d}.asphist
foreach? end

Since we set the normalize parameter = no, the exposure map has units of [cm2*s*counts/photon]. This allows us to simply divide the image by the exposure map to derive an image in units of flux [photons/cm2/s/pixel]. If the setting had been left as yes (the default), the units of the exposure map would be [cm2*counts/photon]. Please see the help file for mkexpmap for more details on this.

Combine the Exposure Maps

Since the individual exposure maps were all created with the same xygrid parameter then we can combine them with a single dmimgcalc call.

unix% ls -1 ?.bin8.expmap
0.bin8.expmap
1.bin8.expmap
2.bin8.expmap
3.bin8.expmap
unix% punlearn dmimgcalc
unix% dmimgcalc '?.bin8.expmap' infile2= out=bin8.expmap
arithmetic operation (): imgout=img1+img2+img3+img4
warning: DETNAM has different value...Merged...
dmkeypar bin8.expmap detnam echo+
Merged
unix% dmhedit bin8.expmap file= op=add key=DETNAM value=ACIS-0123
unix% dmkeypar bin8.expmap detnam echo+
ACIS-0123

The exposure map can be displayed in ds9 (Figure 3). We adjust the DETNAM keyword to better reflect the data (note that the DETNAM for each individual exposure map is ACIS-0 to ACIS-3 in this example).

[Thumbnail image: The ACIS-I array.]

[Version: full-size]

[Print media version: The ACIS-I array.]

Figure 3: Exposure map for the ACIS-I array

unix% ds9 bin8.expmap -cmap b -scale pow -zoom 2

The stripes are due to bad columns in the instrument map and the "power-law" scaling has been chosen to highlight the presence of bad pixels.


4. Normalize the Image by the Exposure Map

The strongly variable exposure near the edge of a dithered field may produce "hot" pixels when divided into an image. While technically proper, these hot pixels can be an eyesore, drawing attention to a noisy, uninteresting portion of the image. The dmimgthresh tool is used to make a "threshold cut" before dividing the image by the exposure map, thus removing the hot pixels:

unix% punlearn dmimgthresh
unix% dmimgthresh 11823.i0123.img 11823.i0123.thresh.img expfile=bin8.expmap cut=1.5%
unix% dmimgthresh bin8.expmap bin8.thresh.expmap cut=1.5%

We also threshold the exposure map so that we can use the exposure map to determine whether a pixel is 0 because there were no counts or because it was removed by the threshold process.

Here we set our threshold at 1.5% of the maximum value of the exposure map. All image pixels with values of exposure less than this value will be set to 0.0 in the output file. You may want to adjust these values for your own observation.

The exposure map is in units of [cm2*s*counts/photon] since it was created by projecting the instrument map (in [cm2*counts/photon]) onto the tangent plane of the observation. To create an image in units of [photon/cm2/s/pixel], we simply need to divide by the exposure map. This is done by the tool dmimgcalc.

unix% punlearn dmimgcalc
unix% dmimgcalc 11823.i0123.thresh.img bin8.thresh.expmap 11823.i0123.norm div
warning: CONTENT has 1 different values.

The messages are related to how the tool merges the header information in the input files. The merging_rules ahelp file explains the rules and how they affect the output file header.

The units of 11823.i0123.norm.div (Figure 4) are photon/cm2/s/pixel.

It is also possible to use dmimgcalc to create an exposure-corrected image where those pixels with no exposure are set to NaN (see Figure 5):

unix% dmimgcalc infile=11823.i0123.thresh.img,bin8.thresh.expmap out=11823.i0123.norm2 \
          infile2= op="imgout=img1/img2"
warning: CONTENT has 1 different values.
[Thumbnail image: The areas of the image where no data is collected are colored in red.]

[Version: full-size]

[Print media version: The areas of the image where no data is collected are colored in red.]

Figure 5: Exposure-corrected image containing NaN values

unix% ds9 11823.i0123.norm2 -scale log -cmap hsv -zoom 2 -prefs nancolor red

The red pixels indicate the NaN values, where the exposure map is 0.

Many CIAO tools will exclude NaN values, as shown in the dmstat output:

unix% dmstat 11823.i0123.norm\* centroid-
File=11823.i0123.norm
11823.i0123.norm
    min:	0 	      @:	( 2920.6594864 2828.7898151 )
    max:	0.00047715386609 	      @:	( 4184.6594864 3940.7898151 )
   mean:	1.3528235331e-06
  sigma:	4.1462884479e-06 
    sum:	0.11933121103 
   good:	88209 
   null:	0 
File=11823.i0123.norm2
11823.i0123.norm2
    min:	0 	      @:	( 3224.6594864 2836.7898151 )
    max:	0.00047715386609 	      @:	( 4184.6594864 3940.7898151 )
   mean:	1.7315960622e-06 
  sigma:	4.6205276295e-06 
    sum:	0.11933121103 
   good:	68914 
   null:	19295 

Calculate the Source Flux

The calculation of the source flux follows the same techniques as used in the single-chip case.


Analysis Caveats

Users should be cautious about analyzing the data for sources near the edges of the ACIS CCDs.

  1. For X-rays passing through the mirrors, the very bottom of each CCD is obscured by the frame store. As a result, some of the events in rows with CHIPY <= 8 are not detected. (The set of rows affected varies from CCD to CCD.) Since the CIAO tools do not compensate for this effect, the ARFs and exposure maps for sources in these regions may be inaccurate.

  2. For sources within about thirty-two pixels of any edge of a CCD, the source may be dithered off the CCD during part of an observation. The aspect histogram, which is used to create ARFs and exposure maps, is designed to compensate for this effect.

  3. An ARF calculated at the edge of a chip will not be accurate since the response tools for spectral extraction (specifically the ARF) assume that 100% of the PSF is enclosed - i.e. on the chip - all the time, which may not be the case. The amount of error introduced depends on how close the source is to the edge, the morphology of the source, and the characteristics of the PSF, which depends on the source spectrum.

  4. A contaminant has accumulated on the optical-blocking filters of the ACIS detectors, as described in the ACIS QE Contamination why topic. Since there is a gradient in the temperature across the filters (the edges are colder), there is a gradient in the amount of material on the filters. (The contaminant is thicker at the edges.) Within about 100 pixels of the outer edges of the ACIS-I and ACIS-S arrays, the gradient is relatively steep. Therefore, the effective low-energy (' 1 keV) detection efficiency may vary within the dither pattern in this region. The ARF and instrument map tools are designed to read a calibration file which describes this spatial dependence.



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


        infile = repro/           Input events file
       outroot = flux/            Root of output files
        (bands = default)         Energy bands, comma-separated list, min:max:center in keV or ultrasoft, soft, medium, hard, broad, wide, CSC
       (xygrid = )                xygrid for output or filename
      (binsize = INDEF)           Image binning factor
     (asolfile = )                Input aspect solutions
   (badpixfile = )                Input bad pixel file
     (maskfile = )                Input mask file
      (dtffile = )                Input dtf file for HRC observations
        (units = default)         Units for the exposure map
 (expmapthresh = 1.5%)            Remove low-exposure regions? '2%' excludes pixels where exposure is < 2% of the maximum
   (background = default)         Method for background removal (HRC-I)
     (parallel = yes)             Run processes in parallel?
        (nproc = INDEF)           Number of processors to use
       (tmpdir = ${ASCDS_WORK_PATH} -> /tmp) Directory for temporary files
      (cleanup = yes)             Delete intermediary files?
      (clobber = no)              OK to overwrite existing output file?
      (verbose = 1)               Verbosity level
         (mode = ql)              
    

History

09 Jan 2012 reviewed for CIAO 4.4: added the option of using the CIAO analysis menu in ds9 to calculate the source flux
06 Feb 2012 fluximage updates were released in the 06 Feb 2012 scripts package: setting badpixfile=CALDB uses the bad pixel file from the CALDB rather than the per-observation version.
16 Feb 2012 fluximage updates were released in the 16 Feb 2012 scripts package: setting badpixfile=NONE uses no bad pixel file when creating the instrument, and hence exposure, maps.
15 Oct 2012 The fluximage script has been updated in the 15 Oct 2012 scripts package: changes include an updated parameter file; output file names are different; and support for spectrally-weighted exposure maps. The observation used as an example has been changed to ObsId 11823, an observation of the supernova remnant RCW 103. An example of running fluximage to create multiple bands has been added (Figure 1). The step-by-step guide has been updated to better match the fluximage script: e.g. use of a FOV file for filtering the observation; using the same energy value for the exposure map rather than taking the peak of the spectrum; the res_xy parameter of asphist is increased to reduce the time it takes to create exposure maps; the exposure map is now also thresholded; and the exposure-corrected image is created with pixels containing 0 (Figure 4) or NaN (Figure 5) where there is no data.
03 Dec 2012 Review for CIAO 4.5; removed mkexpmap warnings;
26 Nov 2013 Review for CIAO 4.6; the pbkfile parameter for fluximage has been removed and is deprecated for mkinstmap; an event file, rather than aspect histogram, should be used for the obsfile parameter of mkinstmap.
17 Dec 2014 Reviewed for CIAO 4.7; minor edits only.


Last modified: 17 Dec 2014
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