gttsmap Help File

Calculates test-statistic map for source localization and detection.

Usage: gttsmap evfile scfile expmap expcube srcmdl outfile irfs optimizer ftol nxpix nypix binsz coordsys xref yref proj

gttsmap computes a significance map based on the maximum likelihood test statistic (TS). (See gtlike help.) The resulting map can be used to localize sources within the analysis region. It can also serve as input to follow up unbinned likelihood analysis. The TS maps are created by moving a putative point source through a grid of locations on the sky and maximizing -log(likelihood) at each grid point with the other, stronger – and presumably well-identified sources – included in each fit. New, fainter sources are then identified at local maxima of the TS map.

In each point of the map, the TS is obtained using the same procedure as in the unbinned likelihood analysis, so many of the gttsmap parameters are the same as the ones used in gtlike. (See gtlike help.)

Note: Run gtdiffrsp before running gttsmap. (See gtdiffrsp help.)

Keep in mind that this tool takes a lot of time to run because a CPU-intensive likelihood analysis is performed at a grid of different positions.

Example: gttsmap

Parameters are passed following the FTOOLs model (i.e., they can be passed interactively by answering a prompt; as a list in a command line; or by editing the parameter file).

To be prompted for gttsmap parameter values, enter (at the command line): gttsmap

Note: Not all parameters are prompted; some are "hidden". In order to change one of the "hidden" parameters, specify its value in the command line. For example, to prevent overwriting an existing output file, type (at the command line): > gttsmap clobber=no

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

> gttsmap  
Event data file [] : events.fits  
Spacecraft data file [] : spacecraft_data_file.fits  
Exposure map file [none] : expMap.fits  
Exposure hypercube file [none] : expCube.fits  
Source model file [] : src_model.xml  
TS map file name [] : TsMap.fits  
Response functions to use [] : P6_V3_DIFFUSE  
Optimizer (LBFGS|MINUIT|DRMNGB) [DRMNGB] :  
Fit tolerance [1e-05] :  
Number of X axis pixels[] 20  
Number of Y axis pixels[] 20  
Image scale (in degrees/pixel)[] 0.5  
Coordinate system (CEL|GAL) [CEL]  
X-coordinate of image center in degrees (RA or l)[] 193.98  
Y-coordinate of image center in degrees (Dec or b)[] -5.82  
Projection method (AIT|ARC|CAR|GLS|MER|NCP|SIN|STG|TAN) [STG]  
.....................!  

This example is performed in the region around (193.98,-5.82). 3C279, 3C273 and the Galactic and Extragalactic background were included in the source model. The expMap.fits file was produced using gtexpmap (see the gtexpmap help), while the expCube.fits file was produced using gtltcube (see the gtltcube help). spacecraft_data_file.fits is the spacecraft file. 20 points were selected for the x- and y-axis respectively. In those points, the likelihood analysis is performed.

The example above could also be run from the command line as follows:

> gttsmap evfile=events.fits scfile=spacecraft_data_file.fits expmap=expMap.fits expcube=expCube.fits srcmdl=src_model.xml outfile=TSMap.fits irfs=P6_V3_DIFFUSE optimizer=DRMNGB ftol=1e-05 nxpix=20 nypix=20 binsz=0.5 xref=193.98 yref=-5.82 coordsys=CEL proj=STG