https://spdf.gsfc.nasa.gov/pub/data/ibex/hi/time_series/histograms/band_4/aareadme.txt

This directory provides 8-day (full IBEX orbit) 
"histogram" files produced by the IBEX-Hi instrument
in energy band 4.  Energy band 4 covers 1.36-2.50 keV.

See the readme files in parent directories, and the 
IBEX team-generated documentation files contained in those
directories.