Defining the energy binning

Since OSA11, you can choose between three different ways to define the energy bins into which the imaging and spectral analyses will be performed, through the parameter sets listed here. We describe now the three possibilities, together with some example.

IMAGING	SPECTRA
IBIS_II_inEnergyValues	IBIS_SI_inEnergyValues
IBIS_nregions_ima	IBIS_nregions_spe
IBIS_nbins_ima	IBIS_nbins_spe
IBIS_energy_boundaries_ima	IBIS_energy_boundaries_spe
IBIS_II_ChanNum	IBIS_SI_ChanNum
IBIS_II_E_band_min	IBIS_SI_E_band_min
IBIS_II_E_band_max	IBIS_SI_E_band_max

IBIS_?I_inEnergyValues,
where the question mark ``?'' is either ``I'' for imaging or ``S'' for spectra. Through this parameter you can provide a file DOL containing the energy binning definition in the format of ISGR_EBDS_MOD, i.e. in three columns specifying the bin number and the corresponding min and max energies.
Each bin has to be specified in the file, therefore the number of rows in the table is equivalent to the number of energy bins.

IBIS_nregions_*
IBIS_nbins_*
IBIS_energy_boundaries_* :

This set of parameters will be read only if IBIS_*I_inEnergyValues is empty.

The user defines ``regions'' of energies, i.e. intervals where the bins are equally spaced. The lower and upper boundary of each region are defined through the IBIS_energy_boundaries parameter, whereas the IBIS_nbins parameter is used to specify the number of bins that will be computed in the given region (positive values for linear spacing, and negative values for logarithmic spacing). Any combination of linear or logarithmic spaced bins, as well as gaps, can be specified.

For example, the combination of parameters:
IBIS_nregions_spe=3
IBIS_nbins_spe="4 0 -2"
IBIS_energy_boundaries_spe="20 80 100 200"

will produce a total of 6 energy bins:
4 linearly spaced bins between 20 and 80 keV: 20-35, 35-50, 50-65, and 65-80 keV
no bins between 80 and 100 keV (i.e., the value of 0 in IBIS_nbins_spe)
and 2 logarithmically spaced bins between 100 and 200 keV: 100-141.4 and 141.4-200 keV. The binning of spectra will be stored in the file isgri_user_bins_spe.fits, which could be used as input of IBIS_SI_inEnergyValues.

For imaging, the combination of parameters:
IBIS_nregions_ima=3
IBIS_nbins_ima="1 2 1"
IBIS_energy_boundaries_ima="20 40 100 200" will produce a total of 4 bins: 20-40, 40-70, 70-100, and 100-200keV. The binning of images will be stored in the file isgri_user_bins_ima.fits, which could be used as input of IBIS_II_inEnergyValues.

IBIS_*I_ChanNum
IBIS_*I_E_band_min
IBIS_*I_E_band_max :

This set of parameters will be read only if IBIS_*I_inEnergyValues and IBIS_nregions_* are both empty. Warning: the energy bins defined through this set of parameters is limited to a maximum of 10 bins. To specify more than 10 bins, use the other (sets of) parameters described above.

In this case you are defining, one after the other, the min and max energies of all the bins.
For example the combination
IBIS_II_ChanNum = 3
IBIS_II_E_band_min = 20 40 100
IBIS_II_E_band_max = 40 80 200

will produce 3 bins: 20-40, 40-80 and 100-200 keV.

For lightcurves, where the number of energy bins is always limited, you can instead provide the min and max energy of each required bin throught the parameters: ILCR_num_e, ILCR_e_min, ILCR_e_max (in a similar way as described for the IBIS_*I_ChanNum, IBIS_*I_E_band_min/max parameters above).