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

This aareadme file was significantly edited in November, 2010,
to reflect significant changes made by the IBEX team in going 
from Release 1 to Release 2 in the organization and content
of digital and PNG-format ENA images from the IBEX-Hi instrument.  

Each release was expected to cover six months of data, 
corresponding to the interval required to accumulate the
data needed for all-sky ENA maps.  However, Release 2
includes (only) IBEX-Hi map data for both the first and 
second six months of IBEX operations.  Release 1 IBEX-Hi 
images remain on nssdcftp, and are addressed near the end of 
this readme file, but can be considered to be superseded by 
the Release 2 data.

The Release 2 data consist of digital and image (PNG) versions
of maps, in both spacecraft frame and, as Compton-Getting corrected, 
heliospheric frame, in 5 IBEX-Hi energy bands (0.52-0.95, 0.84-1.55, 
1.36-2.50, 1.99-3.75, 3.13-6.00 keV) for the first and second 6-month 
intervals ("epochs 1 and 2").  In addition, for the heliospheric frame, 
there are 6 monoenergetic maps (at 0.71, 1.11, 1.74, 2.73, 3.0, 4.29
keV) for each epoch and 5 monoenergetic maps (exclude 3.0 keV from 
prior list) accumulated over the combination of epochs 1 and 2.

Our IBEX-Hi directory is, as previously, separated into digital
data and image (PNG format) data subdirectories.  Each of these 
has two subdirectories, for release_1 and release_2.  The release_1
subdirectories have the map files that were previously directly 
within the digital data and image data subdirectories.  The 
release_2 subdirectory itself has five subdirectories corresponding
to the IBEX team's structure:
map1 (Epoch 1, spacecraft frame data)
map2 (Epoch 2, spacecraft frame data)
map1_CG (Epoch 1, heliosphere frame data)
map2_CG (Epoch 2, heliosphere frame data)
map_combined1_2 (Epochs 1+2, heliosphere frame data)
Each of these subdirectories has ENA flux maps plus much ancillary
data, as described in more detail in lower lying readme files.

Release 1 data 

(Original content of this readme file follows.)

This directory provides subdirectories containing files 
of both digital and image (png) versions of maps of 
ENA fluxes in each of the IBEX-Hi energy bands (except
the lowest energy band at 0.38-0.59 keV).  This 
directory also includes a descriptive file created by 
the IBEX team.

Each full-sky map takes 6-months to accumulate, owing
to the way only a single 6.5 deg wide swath of sky is
seen during a given 8-day orbit while the spin axis is
sunward pointing.  Near each perigee, the spin vector 
direction is adjusted to regain its sun-pointing character.

The sky is binned into 720 0.5 deg longitude bins by 30
5 deg latitude bins, in J2000 ecliptic coordinates,
and 6-month-accumulated/averaged ENA (hydrogen) fluxes 
in each bin are given in the data files.

Files are named as HiMap-oBBB-oCCC_720x30-flux-D.EEE, where

BBB is the orbit number of the first orbit contributing to the file
CCC is the orbit number of the last orbit contributing to the file
(BBB and CCC include leading zeroes.)
D gives the energy band number (2, 3, ...6)
EEE is "txt" for the digital files, "png" for the images.