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Suzaku Guest Observer Facility

Analysis of Early Release Data

2005 December 2


The Suzaku project at ISAS/JAXA have released selected calibration observations from the early phase of the mission. Here, we provide a quick guide on how to analyze these data.

These notes should be considered preliminary and experimental. They cover cleaning XIS hot and flickering pixels, making XIS and HXD products (especially spectra), how to use xselect to catalog all the event files for a source, how to filter by grade, how to select events based on housekeeping information, how to make summed images of all 4 XIS.

Some options in xselect can be set before running using the pset command. To change the default mission to Suzaku and to ensure thatall extensions are copied when extracting events files give the following commands from the unix command line

pset xselect default_mission="SUZAKU"
pset xselect copyall=yes

The latest version of HEAsoft (6.0.4) should be installed.

Cleaning XIS hot/flickering pixels

The cleansis ftool originally written for ASCA SIS by Eric Gotthelf has been generalized first for Swift XRT and now for Suzaku XIS. However, this generalized version is not available yet in a standard HEAsoft release. You need to update your version of cleansis by downloading cleansis.f and replacing the copy in ftools/asca/src/cleansis in your source distribution of HEAsoft. Running hmake followed by hmake install in this directory will build the new version.

To run cleansis on Suzaku XIS event files type from the command line cleansis chipcol=SEGMENT , give the input and output filenames and use the default values of the remaining parameters.

cleansis can be run from within xselect by giving the command sisclean and choosing option number 2.

Generating XIS products in xselect

Xselect sets reasonable default options for XIS products. The image and wmap are binned up 8 times and when being written out the spectrum is truncated at 4096 channels to match the available response matrix files.

(If you have a version of HEAsoft earlier than 6.0.4 you will need to download a new xselect.mdb file. To use this you can do one of the following

  • replace the copy in your HEAsoft source distribution in ftools/xselect/common and install it using hmake install in this directory
  • if you only have the HEAsoft binary distribution then install the new xselect.mdb in ftools/operating-system/bin where operating-system is the appropriate directory for you system (it is the end of the directory string written by eg printenv HEADAS).
  • if you don't have write-access to your HEADAS distribution you can setenv XSELECT_MDB directory-tree/xselect.mdb where directory-tree is the location you have placed the file.

There was also a bug in earlier versions that caused events to be lost when reading both 3x3 and 5x5 event files if the 5x5 file was read first.

Generating HXD products in xselect

The current version of Xselect sets defaults correctly for all products. Pre-6.0.4 versions required the revised xselect.mdb (see above) and also required the command set phaname PI_PIN before extracting spectra from PIN event files. This is no longer required.

Reading in all event files for an instrument

Xselect has a handy ability to make a catalog of the available data. For instance :

xsel:ASCA> set mission suzaku
xsel:SUZAKU> set instr xis0
xsel:SUZAKU-XIS0 > set datadir xis
 
Setting data directory to /Volumes/Documents/DATA/Suzaku/Fornax/xis/evt/
Setting mkf directory to /Volumes/Documents/DATA/Suzaku/Fornax/auxil/
 
xsel:SUZAKU-XIS0 > make cat
> Default filter for the catalogue (NONE for none, DEF for default) [DEF] 
Using default selection expression: INSTRUME=='XIS0'
 
******************** Observation Catalogue ********************
 
Data Directory is: /Volumes/Documents/DATA/Suzaku/Fornax/xis/
HK Directory is: /Volumes/Documents/DATA/Suzaku/Fornax/xis/
 
 
        OBJECT      DATE-OBS    TIME-OBS    DATE-END    TIME-END    EDITMODE
      1 Fornax_Clus 2005-09-13  01:29:50    2005-09-14  11:46:46    3x3
      2 Fornax_Clus 2005-09-13  15:53:34    2005-09-13  22:59:10    5x5

xsel:SUZAKU-XIS0 > choose 1-2 
 
   Setting datamode to STANDARD
 
 
Getting Min and Max for Energy Column...
Got min and max for PI:     0   4095
 
 
Number of files read in:    2
 
Files currently in use:
 
   1   ae20050913_0130_1200_xis0_3x3_cl.evt
   2   ae20050913_0130_1200_xis0_5x5_cl.evt
(In pre-6.0.4 versions doing this for the HXD actually caused one of the event files to be deleted !)

Filter by grade

Filtering by grade can be performed by two possible commands eg
xsel> filter grade "0,2-6"
xsel> filter column "GRADE=0:0 2:6"
The latter was required for earlier Suzaku processing versions which did not have the TLMIN/MAX keywords for the GRADE column.

Selecting on housekeeping information

NOTE: The HEAsoft 6.0.4 and earlier versions of xselect will not automatically find the housekeeping information due to an incompatibility between the current xselect.mdb file and the directory structure of the early release data. If this is the case, you can download the new xselect.mdb file, or issue the command
xsel:SUZAKU-XIS0 > set mkfdir ../../auxil
in xselect.

After the set-up above we can get a list of available housekeeping parameters by show param mkf. To plot lightcurves of any of these parameters use mkfbin followed by plot mkf.

To select events based on housekeeping information use select mkf and then give either a C-style or Fortran-style selection string. This will create a GTI file which will be used for any subsequent products (using extract or bin). This GTI file can be saved by save mkf_sel.

Making summed images from all 4 XIS

The easiest way to do this is not within xselect but within ximage. Suppose the four event files are called xis0.evt, xis1.evt, xis2.evt, and xis3.evt. Then the following ximage commands produce a summed image.
read/rebin=4 xis0.evt
save
read/rebin=4 xis1.evt
sum
save
read/rebin=4 xis2.evt
sum
save
read/rebin=4 xis3.evt
sum
save
smooth
The rebinning and final smooth produce an image well-matched to the psf. To produce an image from a restricted range of PI bins replace the read commands by eg
read/rebin=4/ecol=PI/emin=200/emax=1500 xis0.evt


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This file was last modified on Thursday, 22-Jun-2006 17:52:24 EDT

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