The IBEX second data release consists of maps of the heliosphere in two
epochs, plus maps made from the combination of the two epochs.  The data
release also contains a preprint of McComas et al. 2010, "The evolving 
outer heliosphere: Large-scale stability and time variations observed by 
the Interstellar Boundary Explorer".

The maps provided in the second data release were make using data taken
taken with the IBEX Hi sensor in its energy bands 2 through 6.  The first 
epoch's maps, found in directories Map1 and Map1_CG, were made using data 
from orbits 11 through 33 (December 2008 through June 2009);  the second 
epoch's maps, found in directories Map2 and Map2_CG, were made using data 
from orbits 34 through 56 (June 2009 through December 2009).  The combined
maps were made with data from orbits 11 through 56.

There are five map folders in the IBEX second data release.  Folders Map1
and Map2 contain maps in each of the five Hi sensor energy bands of the 
ENA flux as seen the IBEX spacecraft frame.  Folders Map1_CG and Map2_CG 
contain Compton-getting-corrected maps in the heliospheric frame for each 
of the two epochs;  these folders also contain monoenergetic maps at five 
energies derived from the maps in the Hi sensor energy bands.  The 
monoenergetic maps created from the combination of epoch 1 and epoch 2
Compton-getting-corrected data are found in the folder Combined_Maps.

In the folders, each map is shown as a .png file, and the data used to
calculate that map are stored in a number of .txt files with the same
filename prefix.  The files with prefix "ha60.hide-trp-flux100-hi-X" are 
from data detected the Hi sensors energy band "X", where X ranges from 2 to
6.  The files with prefix "ha60.hide-trp-mono_80-Y.YY" are monoenergetic 
maps at the energy "Y.YY" keV.  The files in the Combined_Maps folder begin 
with "combined-Y.YY", where Y.YY is, again, energy in keV.

Each .txt file consists of header - - lines beginning with '#' - - followed 
by the map grid data in ASCII format.  The map grid consists of 60 bins 
in longitude and 30 bins in latitude, corresponding to six-degree-square 
pixels.  As consecutive orbits differ in longitude by ~7 degrees, the bins 
in longitude are centered on the orbit longitude and any gaps are filled 
using a "nearest neighbor" method in the longitudinal direction.  The maps 
were constructed only using data collected in times of clean sensor viewing.

The text files which are labelled "flux" give the Hydrogen ENA flux as a 
function of J2000 ecliptic coordinates.  The flux map is also shown in a
corresponding .png file.  The .txt files used in the calculation of the
flux file are also given:

  - the "cnts" file gives net counts per bin
  - the "ener" file gives energy per bin
  - the "fexp" file gives net exposure time per bin
  - the "fraw" file gives raw counts per bin
  - the "fsnr" file gives the S/N ratio of the flux per bin
  - the "fvar" file gives the variance of the flux per bin
  - the "numb" file gives the number of samples per bin

Each .txt file consists of 30 rows of data, each with 60 columns.  Row 1 
corresponds to the South Ecliptic Pole, while row 30 corresponds to the 
North Ecliptic Pole.  The columns start at ecliptic longitude 0 and step 
through to ecliptic longitude 360:  the values of the first and last columns 
in each map are identical.  The layout of the columns corresponds to Solar
Ecliptic East Longitude, right to left as seen outward by IBEX.

Contact:  Nathan Schwadron (n.schwadron@unh.edu).