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gtrspgen.txt
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gtrspgen.txt
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NAME
gtrspgen - Creates a "Detector Response Matrix" (DRM or RSP) FITS
file from the multi-dimensional response functions.
USAGE
gtrspen respalg specfile scfile outfile irfs time thetacut
dcostheta ebinalg emin emax enumbins denergy ebinfile
DESCRIPTION
The gtrspgen tool produces a Response Matrix (RSP) file
required to analyze a binned spectrum in an HEASARC standard
(i.e. XSPEC compatible) format. The response matrix is
computed from the detailed response functions provided by the
LAT instrument team. The elements of the matrix are directly
related to the probability of an incident photon with a true
energy of E being detected by the LAT with an apparent energy
E'. The source position, the observation time, and energy
grid are extracted from a type-I PHA (spectrum) file, while
the pointing/livetime history file provides the instrument
orientation during the observation. The tool has two main
options called "GRB" and "PS". The "GRB" option is for short
observations during which the instrument's pointing does not
change significantly. This is relevant for most gamma-ray
burst observations. The "PS" option is for an observation
relevant to a point source over more than a fraction of an
orbit, requiring that the instrument response be averaged over
the different source directions in instrument coordinates.
This tool needs as input two files: A pointing history or
"spacecraft" file covering the time of the observation, which
can be obtained from the Fermi Science Support Center (FSSC)
web site, and a PHA file, which can be created using the gtbin
tool (see the gtbin help). For the LAT data have to
be binned into energy channels using the gtbin tool. But the
first step in the analysis is to select all the counts from a
region of 10 to 15 degrees around the burst position from the
time range that includes the burst. These counts can be
selected using the gtselect tool. For further information on
how to perform a Binned GRB Spectral analysis using the LAT
data it is highly recommended to read the Cicerone Manual:
http://fermi.gsfc.nasa.gov/ssc/data/analysis/documentation/Cicerone/Cicerone_GRBs/GRB_binned_analysis.html
and/or the analysis thread:
http://fermi.gsfc.nasa.gov/ssc/data/analysis/scitools/
PARAMETERS
General Parameters
respalg [string: GRB|PS]
The type of response computation to perform, either GRB or PS.
If set to GRB, the response will be computed for a single
specific time supplied by the user. If set to PS, a response
from a longer observation will be computed. The default value
is GRB.
specfile [file]
Name of input spectrum file, in PHA format.
scfile [file]
Spacecraft data file.
outfile [file]
Name of output response file, in the HEASARC "RSP" format.
irfs [string]
The instrument response function that will be used.
(sctable = SC_DATA) [string]
Table containing spacecraft data.
(resptpl = DEFAULT) [file]
The full path to the template used to create the output file. This
should not normally be changed. If DEFAULT is given, the rspgen
application will use the standard template for LAT RSP files. This is
a hidden parameter. The default value is "DEFAULT".
GRB Response Parameters
time = 0 [double]
The time of the burst in Mission Elapsed Time (MET) seconds.
Point Source Response Parameters
thetacut = 60 [double]
The maximum angle cutoff for the differential exposure computation in
degrees.
dcostheta = 0.05 [double]
The bin size to be used for the spacecraft pointing history
(cos(theta)).
Energy Binning Parameters
ebinalg = LOG [string: FILE|LIN|LOG]
Indicates how the output energy bins will be specified. Legal values are
FILE (bins will be read from a bin definition file), LIN (linearly
uniform bins), and LOG (logarithmically uniform bins). This is only
used if energy binning is required by the output type selected by the
algorithm parameter. The default value is LOG.
(efield= ENERGY) [string]
This is the name of the field containing the energy values for energy
binning. This is a hidden parameter. The default value is consistent
with the event LAT data file format.
emin = 30 [double]
The lowest energy of the first interval for linearly or
logarithmically uniform bins in MeV. Only used if ebinalg is LIN or
LOG. The default value is 30 MeV.
emax = 200000[double]
The highest energy of the last interval for linearly or
logarithmically uniform bins in MeV. Only used if ebinalg is LIN or
LOG. The default value is 200000 MeV.
enumbins = 100 [integer]
The number of bins for logarithmically uniform bins. Only used if
ebinalg is LOG. The default value is 100.
denergy = 50 [double]
The width of linearly uniform bins in MeV. Only used if ebinalg is
LIN. The default value is 50.
ebinfile = NONE [file]
The name of the energy bin definition file. Only used if ebinalg is
FILE. The default value is "NONE".
Other hidden parameters:
(chatter)
This parameter fixes the output verbosity: no screen output
(0), nominal screen output (2), maximum verbosity (4). The
default value is 2.
(clobber = yes)
If true, an existing file of the same name will be overwritten.
This is a hidden parameter. The default value is: "yes".
(debug = no)
Activate debugging mode. 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 if "yes" is
specified. The default value is "no".
(mode = ql)
Mode of automatic parameters. The default value is "ql".
EXAMPLES
The way that the parameters are passed follows the FTOOLs model: They
could be passed by answering prompts, as a list in a command line,
or by editing the parameter file.
To be prompted for gtrspgen simply type in the command line:
>gtrspgen
This will prompt for parameter values. Beware that not all parameters
are prompted: some of the parameter are "hidden". If you want to
change one of the "hidden" parameter you may specify its value in the
command line. For example if you do want to open the GUI option type
in the command line:
>gtrspgen gphinumbins=4
An example of how to run the gtrspgen tool is given below:
> gtrspgen
This is gtrspgen version ScienceTools-v9r33p0-fssc-20140317
Response calculation method (GRB|PS) [GRB]
Spectrum file name[] GRB.pha
Spacecraft data file name[] spacecraft_data_file.fits
Output file name[] GRB.rsp
Time of GRB (s)[0.] 252374400
Response function to use [CALDB] CALDB
Algorithm for defining true energy bins (FILE|LIN|LOG) [LOG]
Start value for first energy bin in MeV[30.]
Stop value for last energy bin in MeV[200000.]
Number of logarithmically uniform energy bins[100]
In this case the GRB option was chosen. The spectrum file was
generated previously with gtbin with the name: GRB.pha.
The same task can also be run in the command line in this way:
>gtrspgen respalg=GRB specfile=GRB.pha scfile=spacecraft_data_file.fits
outfile=GRB.rsp time=252374400 irfs=CALDB ebinalg=LOG emin=30
emax=200000 enumbins=100
SEE ALSO
* gtbin
* gtselect
* The Cicerone Manual:
http://fermi.gsfc.nasa.gov/ssc/data/analysis/documentation/Cicerone/Cicerone_GRBs/GRB_binned_analysis.html