Download INTEGRAL Science Data Centre IBIS Analysis User Manual

Figure 15: A part of the GROUPING extension table of an isgri sky ima.fits file.
7.1.2
Displaying the Results from the Image Step
It is convenient to look at the images with the help of the ds9 program. First create a region file from the
catalog using the cat2ds9 program. In the example below we create the region file found.reg with all the
sources found in the mosaic image, isgri mosa res.fits, for the first energy band (extension [2]), and a
region file cat.reg with all sources that were in the input catalog isgri catalog.fits.
cd $REP_BASE_PROD/obs/isgri_gc
cat2ds9 isgri_mosa_res.fits\[2] found.reg symbol=box color=green
cat2ds9 isgri_catalog.fits cat.reg symbol=box color=white
To see the resulting images:
ds9 $REP_BASE_PROD/obs/isgri_gc/isgri_mosa_ima.fits\[2] \
-region $REP_BASE_PROD/obs/isgri_gc/cat.reg \
-cmap b -scale sqrt -scale limits 0 60 -zoom 2 \
$REP_BASE_PROD/obs/isgri_gc/isgri_mosa_ima.fits\[4] \
-region $REP_BASE_PROD/obs/isgri_gc/found.reg \
-cmap b -scale sqrt -scale limits 0 60
In Figure 16 you see the INTENSITY (left, $REP BASE PROD/obs/isgri gc/isgri mosa ima.fits[2]) and
the SIGNIFICANCE (right, $REP BASE PROD/obs/isgri gc/isgri mosa ima.fits[4]) mosaic images in
the 20–40 keV energy range. In the left image we have shown all catalog sources (white boxes), and in
the right one only the detected ones (green boxes). The color scale at the bottom gives the significance
values. Although we used here a square-root scaling (sqrt) that enhances the structure in the low-values
(the background) we now have a very clean mosaic image compared to images obtained with OSA versions
prior to OSA 9. The issue of spurious new sources detected by the software at the position of the “ghosts”
of true sources is therefore much reduced.
ISDC – IBIS Analysis User Manual – Issue 10.1
25