Lightcurves are produced for each science window:
scw/0051004X0010.001/isgri_lcr.fits (X=1..5)
To create a merged lightcurve in the 20-40 keV energy range (i.e. to store in one file all the available lightcurves of a given source) use lc_pick:
lc_pick source="4U 1700-377" attach=n \
group=og_ibis.fits+1 lc=4U1700-377.fits emin="20" emax="40"
The result is written to 4U1700-377.fits. It is possible to
create more than one merged lightcurve at a time if you specify a list
of desired minimum energies with the parameter emin. If you
have more than one energy range with the same minimal energy, then you
should use the parameter lcselect to define the unique energy
band, otherwise the lcselect parameter can be omitted.