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You are here: Science»  IXO Simulation Tools»  How to run simx

How to run simx

Download simx-0.5.1.tar

First, install simx following the directions on the Downloading and Installing simx page.

Simx uses the ever-popular IRAF interface that should be familiar to FTOOLS and CIAO users. It expects to find its parameter file in a directory pointed to by PFILES. If you are an FTOOLS user, you probably have a directory 'pfiles' in your home directory, e.g. /home/user/pfiles. In this case, simply copy the simx.par file in the pfiles directory to this directory and start FTOOLS; e.g.:

Alternatively, you can simply set the PFILES environment variable to point to the pfiles directory in simx:

Note that the syspfiles/ directory contains a 'pristine' version of the same file in case the one in pfiles is corrupted somehow.

To run simx, simply set the simulation parameters in simx.par to the desired values by editing the file directly in an editor (this method is somewhat risky) or installing FTOOLS and using pset, e.g.:

(see (4) for a list of parameter options) and then run simx:

The code will generate an output event file in the current directory which can be viewed with ds9 or used with the CIAO tools dmextract or the FTOOLS xselect. A modified version of xselect.mdb is needed to use these files with xselect; it can be found in the test directory of simx. To use this file with xselect instead of the default xselect.mdb that comes with FTOOLS, set the following environment variable:

Complete List of User Parameter Options:

OutputFileName

The output event file stem; final file will be this step with "_evt.fits" appended.

PointingRA

Right Ascension (in decimal degrees) of the pointing direction of the satellite.

PointingDec

Declination (in decimal degrees) of the pointing direction of the satellite

Exposure

Exposure time (in seconds)

SourceFlux

Total source flux (in erg/cm²/s); for IXO, a source with 10^-13 erg/cm²/s is reasonably bright.

SourceImageType

Either Image or Point; if Image, a FITS image file must be provided as the SourceImageFile parameter. If Point, the point source position must be provided in SourcePointRA and SourcePointDec

SourcePointRA

Right Ascension (in decimal degrees) of the point source; only used if SourceImageType = Point. If this value and the SourcePointDec match the PointingRA and PointingDec, the source will be centered on the detector.

SourcePointDec

Declination (in decimal degrees) of the point source

SourceImageFile

FITS-format file containing the image to simulate

SourceSpectrumType

One of XSPEC_File, Sherpa_File, or Mono. If set to Mono, the source is assumed monoenergetic with the energy set in the MonoEnergy parameter. If XSPEC_File, it is assumed the spectrum is output from XSPEC using the commands

XSPEC> ...define model spectrum...
XSPEC> plot model
XSPEC> iplot
PLT> wdata model.dat
PLT> quit

In this case, the file will have at least 3 columns, Energy (in keV), delta-Energy, and flux (in ph/cm²/s/keV); the first three rows are ignored as they normally contain text. If Sherpa_File is the parameter, it is assumed the spectrum file comes from a Sherpa model created (in CIAO 3) via:

sherpa> ...define model spectrum...
sherpa> write source source.dat

In this case, the file will have 2 columns, Energy (in keV), and Flux (in ph/cm²/s/keV). If you generate the spectrum file some other way than XSPEC or Sherpa, simply output the spectrum in this format (two columns, energy and flux) and simx should be able to read it.

SourceSpectrumFile

The name of source spectrum file, if SourceSpectrumType=XSPEC_File or Sherpa_File

MonoEnergy

The energy (in keV) of the mono-energetic spectrum if SourceSpectrumType = Mono

RandomSeed

The initial random seed. If you set this to -1, the code will use the current time to seed the random number generator, while any other value will always generate the same sequence of random numbers.

MissionName

Can be set to IXO or Generic; for all IXO uses, this should be kept at IXO.

InstrumentName

This can be set to CalCore (for the core 40×40 calorimeter array), CalFull (for the full 5 arcmin 52×52) calorimeter array, which has a larger deadtime and lower resolution), or WFI (the Wide Field Imager).

FilterName

Can be set to either None (no filter), or to BSDO (Bright Source Defocusing Optic) which diffuses bright sources to a much larger field.

File_bkgnd

Path, including the filename, to the desired background pha file.

File_arf

Path, including the filename, to an effective area file. At the moment, these are not used for any IXO responses.

File_rmf

Path, including the filename, to the Calorimeter or WFI/HXI response file.