Skip banner and navigation tools.

Dept. of Physics & Astronomy
XROA

US Site | Italian Site | UK site

Skip sidebars of related page links.

Home > Data Analysis > BAT > Images

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.

>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.