https://spdf.gsfc.nasa.gov/pub/data/ibex/hi/maps/digital_data/aareadme_ibex_hi_maps_digital.txt

Release_1 data were for the first six months of 
IBEX operations (Epoch 1, 12/2008 - 6/2009).

Release_2 data, issued about 6 months after 
Release_1, were IBEX_Hi maps and related files
and covered both Epochs 1 and 2 (06/2009 - 12/2009).

Release_2 data were significantly different from 
Release_1 data in organization and content.  
Release_1 IBEX-Hi map data were superseded by
Release_2.