How to define a user GTI for SPI analysislast update of this page: 28.02.2003
Here I describe how to create a good time interval, which is then used by the SPI analysis software. Using this, you can in- or exclude certain time periods in your analysis. This is particular interesting for short events, like GRBs.
- create an empty GTI structure:
dal_create obj_name="usergti.fits" template="GNRL-USER-GTI.tpl"
- Fill some keywords (ftools command; you can
of course also set the keywords by hand using e.g. fv):
fparkey value=0.0 fitsfile=usergti.fits\ keyword=TSTART
fparkey value=10000.0 fitsfile=usergti.fits\ keyword=TSTOP
fparkey value=GOOD fitsfile=usergti.fits\ keyword=GTI_TYPE
TSTART and TSTOP define the start and end validity of your selection, not the selection itself.
The GTI_TYPE can be 'GOOD' (use the time specified in the user GTI file) or 'BAD' (exclude the time specified in the user GTI file)
- open the fits file (e.g. with fv):
- click on 'Table'
- click on 'Edit'
- select 'Insert' and then 'row'
- insert as many rows as you want to have good time intervals
- fill in the row either the UTC or the IJD or the OBT columns corresponding to your good/bad time you want to define. It is only necessary to fill ONE time format.
- 'Save' the fits file
- Now you can use the 'usergti.fits' file in your analysis; when
you run spi_science_analysis, set the following parameters to activate
your personal GTI (this example assumes that you defined the GTIs in
spi_gti_creation_use_gtis,s,ql,"DATA_GAPS USER",,,"Input GTI names of all SPI GTIs (ATTITUDE DATA_GAPS USER)" spi_gti_creation_usergtiname,s,ql,"usergti.fits[GNRL-USER-GTI]",,,"User defined GTI table" spi_gti_creation_usergtiformat,s,ql,"UTC",IJD|UTC|OBT,,"Time format used from user defined GTI table (IJD, UTC, OBT)"
In case of questions and comments: contact me.