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PICsIT Image Reconstruction

To start the analysis, go to the working directory $REP_BASE_PROD/obs/picsit_ima and call the ibis_science_analysis script:

cd obs/picsit_ima
After a few seconds, the main page of the IBIS Graphical User Interface (GUI) appears, as shown in Figure [*]. Press "Reset"-button to be sure that you have the default ISDC_ENV parameters.
Figure: Main page of the IBIS GUI
Image gui_main

For PICsIT there were no major changes since the creation of revision 2 data, so you can start directly from the BIN_I level (startLevel=BIN_I). The end level for PICsIT image creation should be the default endLevel=IMA2. Disable ISGRI analysis by checking SWITCH_disableIsgri button, and enable PICsIT by unchecking SWITCH_disablePICsIT button.

PICsIT operates in an energy range (0.175-10 MeV) where background subtraction plays a very important role. The OSA for PICsIT provides a default set of maps for the background subtraction in certain energy bands, selected to optimize the instruments performance. By default, the software will automatically take subtraction with one set of maps (with about 1.7 Ms of integration time). The default energy bands are (in keV) for single events: , , , , , , , . For multiple events: 336 - 448, 448 - 672, 672 - 1036, 1036 - 1848, 1848 - 3584, 3584 - 6720, 6720 - 9072, 9072 - 13440.

This works for standard mode (mode 41) [*] only.

To select parameters specific for PICsIT analysis press the PICsIT button. The PICsIT GUI page is shown in Figure [*].

Figure: PICsIT page of the IBIS GUI
Image gui-pics

Depending on the observation mode (staring or dithering), there are two ways to analyze the PICsIT data. The first, by using the parameter staring=yes, can be used only for staring observation, where the difference between all the pointings is less than the value defined by the tolerance parameter(for PICsIT use tolerance=0.1). In this case, the corrected shadowgrams are integrated before the deconvolution. If staring=no, then deconvolution will be performed for each science window individually.

The science windows we use in the current example were observed in staring mode, so check the staring button.

SCW1_BKG_P_method defines the way to normalize the background maps to the observed shadowgram before performing the background subtraction. 0 means scaling with exposure, and 1 means scaling with the average counts value over the whole detector. Both generally provide the same results, though the second method, which serves as default, is sometimes a bit better.

PICSIT_inCorVar defines whether you would like the software to partially correct the variance shadowgram for systematic effects due to the background (value 1), or not, in order to estimate by yourself the degree of systematics present in the deconvolved maps (value 0).

PICSIT_outVarian defines whether you would like to have the variance maps in output (value 1), or not (value 0). Note that the varmosaic tool of HEASOFT needs variance maps to work.

Return to the main GUI window by clicking on OK. Without changing other default parameters, you are now ready to run the analysis; do so by clicking on Run.

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Next: Results of PICsIT image Up: PICsIT data analysis Previous: PICsIT data analysis