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gttsmap.txt
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gttsmap.txt
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NAME
gttsmap - Calculates test-statistic map for source localization
and detection.
USAGE
gttsmap statistic scfile evfile expmap cmap bexpmap expcube srcmdl irfs
optimizer outfile nxpix nypix binsz coordsys xref yref proj
DESCRIPTION
This tool computes a significance map based on the maximum
likelihood test statistic (TS) (see, for example, the gtlike help
and references therein). The resulting map can be used to localize
sources within the analysis region. It can also serve as input to
follow up for the binned and the 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 binned or unbinned likelihood analysis, so many of the
gttsmap parameters are the same as the ones used in gtlike (see
the gtlike help). Note that one should run gtdiffrsp before
running gttsmap (see the gtdiffrsp help).
One should 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.
PARAMETERS
statistic [string]
Statistic that will be used to generate the map. The optional values
are "BINNED" or "UNBINNED".
evfile [file]
Input event file. This is the file containing the LAT event
data. If multiple events files are desired, an ASCII file with the
complete list of them should be entered here with an "@" sign
before the name. For example, if the name of that ASCII file is
"events", then is parameter should be entered in this way:
evfile=@events.
(evtable = EVENTS) [string]
Event table extension name. This is a hidden parameter.
scfile [file]
Spacecraft data file containing information such as the spacecraft
pointing as a function of time. This file could be generated by
gtorbsim for simulated observations (see the gtorbsim help for
further explanation) or more commonly it can be obtained from the
Fermi Science Support Center (FSSC).
(sctable = SC_DATA) [string]
Spacecraft data extension. This is a hidden parameter.
expmap [file]
Exposure map file created by gtexpmap and like those used in an
unbinned likelihood analysis. See the gtexpmap help for further
explanation.
bexpmap [file]
Exposure map file created by gtexpmap and like those used in an
binned likelihood analysis. See the gtexpmap help for further
explanation.
cmap [file]
Counts map file to be used in the binned likelihood analysis.
(psfcorr = yes) [boolean]
Apply psf corrections for point source maps.
expcube [file]
FITS file containing live-time as a function of sky position and
off-axis angle. This file should be generated by gtltcube or could
be provided by the FSSC. See the gtltcube help for further
explanation.
srcmdl [file]
XML file containing the source model definitions for known sources
that are input into your calculation. This source model file is
the same as that used by gtlike (see the gtlike help). The source
model could be generated by the ModelEditor utility or by
following source model templates. See the ModelEditor help for
further explanation.
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”.
evtype [integer]
The evtype to be used in generating the background data. The
default is INDEF which will use the default in the input
file. This can be overridden by entering the desired event
type e.g. 3 for FRONT + BACK events.
outfile [file]
Output FITS file name.
optimizer [string]
Optimizer package to use (see the gtlike documentation), either
MINUIT, DRMNGB, or LBFGS. Due to
the fact that gttsmap calls the same routines as gtlike to obtain
the TS of the detection at each analyzed position, the optimizer
should be the same than the ones used for that tool. The default
value is MINUIT.
(ftol = 1.e-3) [double]
Relative Fit tolerance. This is the fit tolerance for the
likelihood analysis. It is the same parameter used for gtlike. See
the gtlike help for further explanation.
(toltype = ABS)
Fit tolerance convergence type (absolute vs relative).
nxpix [int]
Number of pixels along x coordinate axis, ranging from 2 to 200.
nypix [int]
Number of pixels along y coordinate axis, ranging from 2 to 200.
binsz [double]
Image scale (in degrees/pixel).
coordsys [string]
Coordinate system to use (CEL=J2000 celestial, GAL=Galactic).
xref [double]
X-coordinate of image center in degrees (RA or l).
yref [double]
Y-coordinate of image center in degrees (Dec or b).
proj [string]
Coordinate projection (AIT|ZEA|ARC|CAR|GLS|MER|NCP|SIN|STG|TAN);
see Calabretta & Greisen 2002, A&A, 395, 1077 for definitions of the
projections. Must be AIT, ZEA, or CAR for auto full sky.
(chatter = 2)
This parameter fixes the output verbosity: no screen output (0),
nominal screen output (2), maximum verbosity (4). The default
value is 2.
(clobber = yes)
Overwrite or do not overwrite existing output files. This is a hidden
parameter. The default value is "yes".
(debug = no)
Activate debugging mode. This is a hidden parameter. The default
value 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 = no)
Graphical user Interface (GUI) mode activated is "yes" is
specified. This is a hidden parameter. The default value is "no".
(mode = ql)
Mode of automatic parameters. This is a hidden parameter. The default
value is "ql".
EXAMPLES
Parameters are passed following the FTOOLs model. They can be
passed interactively in response to a prompt, a listed in a
command line, or by editing the parameter file.
To run gttsmap interactively simply type in the command line:
>gttsmap
You will then be prompted for parameter values. Beware that not
all parameter are prompted: some of them are "hidden". If you
want to change one of the "hidden" parameter you should specify
the values in the command line. For example if you do not want to
overwrite an existing file, type in the command line:
>gttsmap clobber=no
An example of how to run the tool is given below:
> gttsmap
Statistic to use (BINNED|UNBINNED) [UNBINNED]
Spacecraft file[none] spacecraft_data_file.fits
Event file[none] events.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 [] : CALDB
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.
That last example could be also run in the command line as follows:
> gttsmap statistic=UNBINNED evfile=events.fits scfile=spacecraft_data_file.fits
expmap=expMap.fits expcube=expCube.fits srcmdl=src_model.xml
outfile=TSMap.fits irfs=CALDB optimizer=DRMNGB ftol=1e-05
nxpix=20 nypix=20 binsz=0.5 xref=193.98 yref=-5.82
coordsys=CEL proj=STG
SEE ALSO
gtlike
gtltcube
gtexpmap