GTIs in SPI data analysis

Current SPI data analyses carried out with the spi_science_analysis script are not making use of any GTIs. In order to eliminate ``bad data'', only entire pointing are excluded from the analysis (see Sect. . In addition, the GTIs required to analyse short bursts such as GRBs can be accounted for automatically by the GRB analysis script. In some cases, you may need to create a GTI anyway, and this can be done following the below procedure.

• Create an empty GTI structure

  dal_create obj_name="usergti.fits" template="GNRL-USER-GTI.tpl"

• fill some keywords (if you prefer GUIs, use fv)

       fparkey value=0.0 fitsfile=usergti.fits\~[1] keyword=TSTART
       fparkey value=10000.0 fitsfile=usergti.fits\~[1] keyword=TSTOP
       fparkey value=GOOD fitsfile=usergti.fits\~[1] 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 with fv

  fv usergti.fits

• 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
• ``Save'' the fits file.