BAT images can be created over any energy bands between 15-350 keV. The following tasks allow both single- and multi-band images to be built. First a Detector Plane Image (DPI) is formed; then a Fast Fourier Transform (FFT) is used to deconvolve the detector plane data from the coded mask pattern. This produces an image in sky coordinates.
>batbinevt detmask=grb.mask [ecol=energy weighted=no outunits=counts] >Input event file name:sw00377487000bevshsp_uf.evt >Output file name: grb_4.dpi >Make light-curve or spectrum: dpi >Histogram time bin size: 0 >Time binning algorithm: u >Energy bin list: 15-25, 25-50, 50-100, 100-350
The output name
grb_4.dpi was chosen because four energy bins (15-25, 25-50, 50-100 and 100-350 keV) were used.
The detector mask (grb.mask) was previously created using bathotpix.
>batfftimage detmask=grb.mask >Input dpi file name:grb_4.dpi >Output image name: grb_4.img >Input attitude file name: sw00377487000sat.fits.gz
This second step performs the Fourier transform. Again, the *sat.fits file is located in the [obsid]/auxil directory.
pcodethresh parameter can also be specified, in order to create a partial coding map. This a value between 0.0 (no partial coding) and 1.0 (fully coded), with values below pcodethresh being set to zero.
>batfftimage detmask=grb.mask pcodemap=yes pcodethresh=0.01 >Input dpi file name: grb_4.dpi >Output image name: grb_pcodemap.img >Input attitude file name: sw00377487000sat.fits.gz
pcodethresh=0.01 is the default and means that at least 1% of the detectors must be illuminated.