Analysis of a Gamma-Ray Burst


In this  exercise  the spectrum and lightcurve of a GRB 031203 are investigated.
Look in the viewgraphs of the talk of N.Produit and find the CGN report which gives the  details of the GRB time, duration and position on the sky.

0. Some setting up


cd
isdc
mkdir root
cp /home/isdc/produit/.rootrc .
cp /home/isdc/produit/root/radec.C root/
cp /home/isdc/produit/addition/addsource/addsource.C root/

1. Convert the information about arrival time and position of GRB into form suitable for analysis.

Convert the information about position and time of GRB into form suitable for OSA analysis

root
.L radec.C
decimal(08,02,30,-39,50,49)
.q

Find the Science Window (SCW) in which the GRB appears  from GCN notice time in UTC

converttime UTC 2003-12-03T22:01:28 ""

2. Locate the GRB on the isgry sky image.

Create the science window list and the observation group

echo "scw/0139/013900150010.001/swg_prp.fits[1]" > scw.lis
og_create scw.lis ogid=0001 obs_id=0001 baseDir="./" instrument=ibis

and run  ibis_science_analysis in this observation group till IMA level.

With the help of ds9 Determine the sources found and locate them on the image. As you can see, the GRB does not appear in the source list.
To force the OSA to analyze the GRB create your own catalog my_cat.fits with tþe help of isdcroot utility

isdcroot $HOME/root/addsource.C my_cat.fits GRB031203 120.625 -39.8469
isdcroot addsource.C my_cat.fits "Vela X-1"
isdcroot addsource.C my_cat.fits "Ginga 0836-429"

Create a region file from my_cat.fits and locate the GRB on isgry sky image with the help of ds9. 


Extract the  lightcurve of GRB by collecting all the photons from the pixels illuminated by the GRB. For this you will neeed the PIF (pixel illumination function) of the GRB:  

cd scw/013900150010.001
ii_pif_build outGRP="swg_ibis.fits" srcDOL=../../my_cat.fits maskDOL=$ISDC_IC_TREE/ic/ibis/mod/isgr_mask_mod_0003.fits outPIF=my_pif.fits

You can look at the shadow pattern cast on the detector by the GRB:

fv my_pif.fits

To see the lightcurve of the birst, use the ii_light tool

ii_light \
outSwg="swg_ibis.fits" \
outLC="lcr.fits(ISGR-SRC.-LCR-IDX.tpl)" \
context="../../../../scw/0139/rev.001/idx/isgri_context_index.fits" \
GTIname="MERGED_ISGRI" \
pifDOL=my_pif.fits \
corrDol=../../rebinned_corr_ima.fits \
num_e=4 \
e_min="20 40 60 100" \
e_max="40 60 100 200" \
delta_t=1


To check the result, open the lightcurve with fv:

fv lcr.fits &
plot time%rate for extention 2


3.  Detailed analysis: using the user GTI.

Now when you have first information about the GRB you can do more detailed analysis.

cd ../../../../
og_create scw.lis ogid=0002 obs_id=0002 baseDir="./" instrument=ibis
cd obs/0002/
cp ../0001/my_cat.fits

Create your own good time interval (GTI) which will select only the photons which came during the GRB.  Run the sceince analysis once more in a new observation group.

gti_user my_gti.fits 2003-12-03T22:01:10 2003-12-03T22:02:00 group=og_ibis.fits


Check your GTI file with fv:

fv my_gti.fits &


Run the analysis software to make the image, 0.5 s resolution lightcurve and the spectrum of the GRB


ibis_science_analysis og_ibis.fits+1 startLevel=COR endLevel=LCR \
SWITCH_disablePICsIT=yes \
CAT_refCat=my_cat.fits \
ILCR_delta_t=0.5 \
SCW1_GTI_gtiUserI=my_gti.fits

Check the results:

ds9 scw/013900150010.001/isgri_sky_ima.fits\[2] scw/013900150010.001/isgri_sky_ima.fits\[3] scw/013900150010.001/isgri_sky_ima.fits\[4]