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In this Section, we give an overview of the analysis of IBIS data.

Each photon detected by IBIS is analyzed with the on-board electronics and tagged with the arrival time, type (ISGRI , PICsIT, Compton[*] etc.), energy, position etc. according to the operation mode (i.e., photon-by-photon, standard, calibration etc.). These data are then sent to ground in telemetry (TM) packets.

During Pre-Processing the TM packet information is deciphered and rewritten into a set of FITS files (RAW data). Then, the local on-board time is converted into the common on-board time (OBT) and the House Keeping (HK) parameters into physical units (PRP data).

These steps are done at ISDC and results stored into the available archive of data. In the Appendix A and B, you will respectively find the description of the raw and prepared data and also the description of the instrument characteristic files that are used in the Scientific Analysis.

INTEGRAL data are organized into the so-called Science Windows (see Introduction to the INTEGRAL Data Analysis [1] for more explanations). During the scientific analysis, all the Science Windows belonging to the same observation are grouped together to form the ``Observation Group''.

Figure [*] shows in details the different steps performed by the scientific analysis script, ibis_science_analysis. This high-level script consists of four smaller ones: ibis_scw1_analysis, ibis_obs1_analysis, ibis_scw2_analysis and ibis_obs2_analysis. ibis_scw1_analysis and ibis_scw2_analysis work on a Science Window basis while ibis_obs1_analysis and ibis_obs2_analysis work on the Observation Group basis. Each subscript performs the tasks shown in Figure [*], explained in more details in the text below.

Figure: Science Analysis Overview
Image analysis_seq_brief

Revision 3 (rev_3) of the INTEGRAL Archive is the default data format and the older Revision 2 (rev_2) archive is no more available. Rev_3 data have been regenerated starting from INTEGRAL telemetry, including an optimal time correlation and the data selection and calibrations used in OSA9. Even if the data correction step (COR), as well as the instrumental GTI and deadtime handling (DEAD) steps have already been performed at science window level, the energy reconstruction has become inaccurate. To fully exploit OSA11 improvements, it is mandatory to rerun the analysis from COR step included, as new algorithms and calibration files are available.

The resulting OSA count rates in scientific products are corrected for the off-axis transparency of the mask supporting structure.

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