The SWIFT BAT Software Guide Version 6.3 30 ... - HEASARC - Nasa

D.5. BATDRMGEN 125
D.5 BATDRMGEN
D.5.1 NAME
batdrmgen - computes BAT detector response matrix (RSP) for a known source position
D.5.2 USAGE
batdrmgen infile outfile hkfile
D.5.3 DESCRIPTION
batdrmgen is the BAT Detector Response Matrix (DRM) generator tool that computes the full
BAT instrument response to incident photons, given the source position information read from an
input PHA spectral file. The output FITS file contains a matrix that represents the mean response
of a detector using mask-weighted analysis. Because BAT is very wide-field, it is not practical to
separate the response into “ARF” and “RMF” components, and for this reason batdrmgen creates
a single response with these components combined (so-called “RSP”). This file should be used in
spectral analysis with software like XSPEC.
The batdrmgen tool accepts as input a pulse height spectrum file produced by the BAT binning
tool ‘batbinevt’. BAT spectra are required to have both a SPECTRUM extension and an
EBOUNDS extension, which describes the energy bin edges used to produce it.
BAT spectra are required to have specific keywords which describe the position of the source in
the field of view. Please note that, as documented in the BAT software manual, users must run
the tasks ‘batupdatephakw’ and ‘batphasyserr’ on their spectra before running batdrmgen. These
other tasks apply several instrument-related corrections which must be in place before the response
matrix is computed.
The batdrmgen tool accepts both “Type I” and “Type II” spectral files. The most common
type of file, Type I files contain a single spectrum (and are produced using the outtype=PHA1
option of batbinevt). Type II files contain multiple spectra in a single extension (and are produced
using the outtype=PHA2 option of batbinevt). The ‘row’ option of batdrmgen allows the user to
select which Type II spectrum to process.
Upon finishing, batdrmgen attempts to modify the input spectrum to record the file name of
the newly created response matrix. By default, it uses the standard RESPFILE keyword for this
purpose, but if a column named RESPFILE is present, it will use the column (and specified row)
instead. This column behavior is useful for Type II spectra, but note that such a column must
exist before calling batdrmgen, otherwise it falls back to using the keyword approach. The spectral
fitting package XSPEC will use either the RESPFILE column or keyword to automatically load
the response matrix.