ii_light

For every PIF found in the Science Window, ii_light extracts simultaneously a lightcurve for each source and one light curve for background in all specified energy bands. Dead pixel, data gaps, off-axis correction, energy low threshold and illumination factors are taken into account.

The method used is a fit of hyperplane through the cloud of points formed by the number of counts versus PIF fraction for every source. In the case of one source this is just a linear regression. The intercept gives the background, while the slope gives the flux of the source in one fully illuminated pixel. Normalization is a number of counts in a perfect detector if source is on axis (half of all detector pixels illuminated).

There are two methods to extract the flux for one source:
1. the source flux is extracted considering the source alone.
2. the source flux is extracted taking into account that other sources are in the FOV.
For a faint source in the PCFOV it is important to take into account all bright (typically larger than 0.1 Crab) sources in the entire FOV, whereas to analyse a faint source in the FCFOV it is necessary to consider only bright sources in the PCFOV.

The sources that need to be considered simultaneously for the lightcurve extraction are the ``essential sources'' (the DOL to the list is stored in source_selectDol parameter). The list however should include the lower possible number of sources (defined through the maxessential parameter). This is due to the fact that extracting simultaneously the flux of many (N) sources takes a longer (of order ) computation time than extracting a source alone.

Care has been taken so that the output structure is compatible with HEASARC tools.
There are no limits on the size of time bin (up to 0.1s), and number of energy bands.

ii_light should be used mainly to check relative variability of bright sources within a given Science Window, rather than for a long term absolute flux estimate. An extended comparison between the lightcurve extraction tool (ii_lc_extract) and ii_light can be found in Grinberg et al. 2011 [16]

Table 28: ii_light parameters.

Name	Type	Description
inSwg	string	DOL of the input Observation Group. default: `` ''
outSwg	string	DOL of the output Observation Group default: `` ''
outLC	string	Dol of the light curves file default: `` ''
context	string	DOL of the context where we can find low threshold default: `` ''
GTIname	string	Name of the GTI to be applied default: `` ''
select	string	Event selection condition default: `` ''
pifDOL	string	Dol of the PIF (or of the index of PIF) default: `` ''
deadDOL	string	Dol of the ISGR-DEAD-SCP" default: `` ''
corrDol	string	DOL of the isgri off-axis corrections default: `` ''
backDol	string	DOL of the background maps default: `` ''
delta_t	real	Time bin in seconds. possible values: 0.1 - 10000 default: 100
num_e	integer	Number of energy channels possible values: 1 - 10 default: 2
e_min	string	List of low energy boundaries default: ``15 40''
e_max	string	List of high energy boundaries default: ``40 300''
onlydet	boolean	Do only detector light curve? default: NO
idxSwitch	string	DOL of the index of pixels switches list. default: `` ''
idxNoise	string	DOL of the index of noisy pixels default: `` ''
evttype	integer	Type of data 0=ISGRI; comprised between 0 and 5 default: 0
source_selectDol	string	DOL containing column NAME of essential sources default: `` ''
maxessential	integer	Max number of essential sources (between 1 and 300) default: 3
cleanobt	boolean	Discard equal time photons default: NO
chatter	integer	Verbosity of output. (0: min verbosity; 5: max verbosity) default: 2
barycenter_correction	boolean	Perform barycentric correction on event times
default: no
RA	float	right ascension of the source to perform barycentric correction (decimal)
default: 360
DEC	declination of the source to perform barycentric correction (decimal)
default: 0

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