Skip banner and navigation tools.

 |  site map

Skip sidebars of related page links.

Creating an image

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. If you initially processed the BAT data using the batgrbproduct wrapper script as described on the index page, then the detector mask will be in the newly created auxil directory, under the name *b_qmap.fits.

>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.

Alternatively, a 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.