Spectral Extraction

It is not possible to extract the spectrum of only the source you are interested in. All sources brighter or compatible with the one you are interested in should be taken into account too. Thus it is strongly recommended, when you deal for the first time with your data, to run the analysis until the IMA2 level, as described in Section 7.1, check the results, and call ibis_science_analysis once again to run the spectral extraction part. The description of the algorithm used for spectral extraction is given is Section 12.9.1.

Launch ibis_science_analysis, and on the main GUI page change Start Level to BIN_S, and End Level to SPE. After that press the ISGRI SPE and LCR button.

Figure 18: Page of IBIS GUI for Spectral and Ligtcurve extraction

On the screen that appears (see Figure 18), you can specify:

Spectral energy binning:
With the help of the parameter IBIS_SI_inEnergyValues you can specify the file (and its extension) describing the desired binning of the response matrix. By default (set with empty line), the latest available file with the rebinned response matrix is used. See sections 8.3 and 9.5 if you want to define your own spectral binning.

Background maps:
With the SCW2_BKG_I_isgrBkgDol parameter you can specify the background map to be used in the spectral and timing analysis. It is recommended to use the same background map as in the imaging case. Default empty value corresponds to the default map ($REP_BASE_PROD/ic/ibis/bkg/isgr_back_bkg_0011.fits).

Input catalog for Spectral and Lightcurve extraction:
By default a spectrum will be created for all sources listed in the isgri_srcl_res.fits catalog created during the IMA step. The position of the source will be taken from RA_FIN, DEC_FIN columns. Note however that spectral extraction is time consuming, and it is not recommended to include sources that are faint in comparison with the source of interest. Moreover it is not recommended to have more than 30 sources in the input catalog, as the software might crash otherwise. Copy isgri_srcl_res.fits to another file, say specat.fits as shown below, leaving only sources with significance higher than a threshold ( in the example below):

cd  $REP_BASE_PROD/obs/isgri_gc
fcopy "isgri_srcl_res.fits[ISGR-SRCL-RES][DETSIG >= 7.0]" specat.fits

(Note, that there should be spaces around " ").

Note that it is important to make the resulting catalog read only to avoid that it gets corrupted during the analysis:

 chmod -w specat.fits

Part of the resulting specat.fits catalog is shown in Figure 19.

Figure 19: List of sources used for the spectral analysis

The same catalog will be used later for the lightcurve extraction.

In the GUI, set the SCW2_cat_for_extract parameter to point to specat.fits (use the browse button to get the full path)and press Ok, the window disappears and you are back to the main GUI page. There, press Run to launch the analysis.