NAME

    gtmodel - Creates a model counts map based on a binned likelihood fit.


USAGE
    
    gtmodel srcmaps srcmdl outfile irfs expcube bexpmap


DESCRIPTION

    This tool is used to facilitate comparisons between the data and model
    predictions. It is recommended to read the gtlike help for more
    explanations. gtmodel creates a model map of a region based on the fit
    parameters. This map is effectively an infinite-statistics counts map
    of the region-of-interest based on your model fit. The gtmodel
    application reads in the fitted model, applies the proper scaling to
    the source maps, and adds them together to get the final map. Before
    running this tool you should run gtsrcmaps (see the gtsrcmaps help for
    more information).


PARAMETERS

    srcmaps [filename]
         FITS file containing the individual source model components that have
         been convolved through the instrument response using gtsrcmaps.
 	 	 
    srcmdl [filename]
         XML file containing the source model definitions. This is the same
         source model file used by gtlike (see the gtlike help). The source model 
	 can be generated by the "ModelEditor" utility or by following source 
	 model templates (see the "ModelEditor" help for further explanation).
	  	 	 
    outfile [filename]
         Name of the output FITS file that will contain the generated counts map.
 	 	 
    irfs [string]
         Instrument response functions. The instrument response (PSF, effective
         area, energy resolution) is currently a function of energy,
         inclination angle (the angle between the source and the LAT normal)
         and photon category. Since the LAT will usually survey the sky, a
         source will be observed at different inclination angles. Each count
         will therefore be characterized by a different instrument response
         function (IRF). The default value is “CALDB”.

    expcube [filename]
	 FITS file containing livetime as a function of sky position and
	 off-axis angle. This file can be generated by gtltcube or obtained
	 from the FSSC website. See the gtltcube help for further explanation.
 
    bexpmap [filename]
         Binned exposure map for on-the-fly source map calculations. If the
         existing file is specified, that file will be used as the exposure
         map. Otherwise, a map with that name will be computed based on the
         energy bands in the srcmaps file. If "none" is given (default value), 
	 the map will be called "binned_exposure.fits".
 
    (convol) [boolean]
	 Perform the convolution of the model maps with the PSF. This is
	 applies only for on-the-fly source map calculations. Default is "yes".
 
    (resample) [boolean]
	 Flag to indicate that the model counts map that is produced should
	 be resample for convolution. The parameter only apply if gtmodel 
	 needs to generate a source map that is not in the file given as 
	 the srcmaps parameter. Default is "yes".

    (rfactor) [integer]
	 Resampling factor to be specified if the "resample" parameter is set
	 to "yes". Default is "2".

    (outtype) [string]
         Enables gtmodel to write counts cube (ccube) or summed counts (cmap,
	 the default value) maps with geometry and energy planes
	 matching the input source file.

    (chatter) [integer]  
         This parameter fixes the output verbosity: no screen output (0),
         nominal screen output (2), maximum verbosity (4). Default is "2".

    (clobber) [boolean]
         If true, an existing file of the same name will be overwritten. 
         Default is "yes".
    
    (debug) [boolean]
         Activate debugging mode. Default is "no". When debug is "no", all 
         exceptions that are not caught and
         handled by individual tool-specific code are caught by a top-level
         exception handler that displays information about the exception and
         then exits. When debug is "yes", such exceptions are not caught by the
         top level code. Instead the tool produces a segmentation violation,
         which is more useful for debugging. When debugging mode is enabled,
         the tool produces more verbose output describing any errors or
         exceptions that are encountered.
    
    (gui) [boolean]
         Graphical User Interface (GUI) mode is activated if set to "yes".
         Default is "no".
    
    (mode) [string]
         Mode of automatic parameters: "h" for batch, "ql" for interactive. 
         Default is "ql".


EXAMPLES
   
    Parameters are passed following the FTOOLs model: They could be passed
    answering from a prompt, as a list in a command line, or by editing
    the parameter file.
     
    To run gtmodel simply type in the command line: 

> gtmodel
 
    The parameter values have to be provided. Not all parameter are prompted: 
    some of them are "hidden". To change one of the "hidden" parameter, the 
    user should specify the values in the command line or modify its mode 
    by editing the parameter file. For example, to avoid overwriting the 
    outfile, the following command line has to be typed:
 
> gtmodel clobber=no

    An example of how to run the tool is given below: 

> gtmodel
Source maps (or counts map) file[]  srcMaps.fits
Source model file[] src_model.xml
Output file[] model_map.fits
Response functions[CALDB]
Exposure cube[] expCube.fits
Binned exposure map[none] bexposure.fits

    That last example could be also run in the command line as follows:

> gtmodel srcmaps=srcMaps.fits srcmdl=src_model.xml outfile=model_map.fits
 irfs=CALDB expcube=expCube.fits bexpmap=bexposure.fits


KNOWN BUGS

Both gtsrcmaps and gtmodel can give incorrect results when used for images
which are very wide. The limit is approximately 270 degrees in longitude.
This means that a single image that covers the full Galactic plane cannot be
made. To work around this limitation, it is possible to create two images,
each of which covers half the plane. These two images may then be combined
together. 

SEE ALSO

    gtlike

    gtsrcmaps
    
    gtltcube