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Phase Resolved Analysis

Read this if you want to perform phase resolved analysis

There are no special tools in OSA for the phase resolved analysis. Below we give some hints on how to apply the existing tools for your needs in different cases. In general, three cases are possible:

1) The time scale you are interested in is bigger than several hours.

In this case you should just select the Science Windows matching your time selection criteria. For this you can use e.g. the keywords TSTART and TSTOP in the header of swg.fits.

2) The time scale you are interested in is in the range of seconds to hours.

In this case the GTI usage is recommended, see Section [*]. Note that if the number of USER GTIs exceed 1000, then the program could become unreasonably slow.

3) You are interested in very short (milliseconds) time scale. Currently this case requires lots of manual work. The idea is to use SCW1_ISGRI_event_select parameter to define your CFITSIO criteria for the phase selection. Unfortunately it is not possible to apply this criterion directly to the TIME column, and you will have to modify the DELTA_TIME column of the third (ISGR-EVTS-ALL) extension of the isgri_events.fits. This file is usually write protected, so in general you will have to copy all the data related to the science window of interest to a new place, and change links.

In the example below, we are working with science window 005100570010, and are interested in T = 20 milliseconds (0.02 s) time bins with zero phase at T0=1170.36 (in IJD). The general selection criterion can be written as:


Here T and T0 are expressed in days, T in seconds, and phase period is split into 100 intervals, i.e., the phase written to column DELTA_TIME changes from 0 to 99. In our example it will look like:

rm -r scw
mkdir scw
mkdir scw/0051
cd scw/0051
cp  directory_of_local_archive__/scw/0051/005100570010.001 .
ln -s  directory_of_local_archive__/scw/0051/rev.001   .
chmod +w   005100570010.001
cd  005100570010.001
chmod +w  isgri_events.fits.gz
fcalc isgri_events.fits.gz\[3] isgri_events_1.fits clname="DELTA_TIME"\
gzip isgri_events_1.fits
mv   isgri_events_1.fits.gz  isgri_events.fits.gz
chmod -w  isgri_events.fits.gz
cd ../
chmod -w  005100570010.001
og_create idxSwg=phase.lst ogid=phase  baseDir="./" instrument=IBIS
cd obs/phase
ibis_science_analysis SCW1_ISGRI_event_select='DELTA_TIME <50'

Note that in this case you create a dead time about which the software is not aware of. Thus you will have to correct the resulted flux by the factor (original exposure)/(real exposure). In the case above we have selected events with phase less than 50, i.e. half of the time was rejected, and the resulted flux should be multiplied by 2.

next up previous contents
Next: PICsIT data analysis Up: Useful recipes for the Previous: Timing Analysis without the