Data Set Overview  :   A global map of the concentration of iron, with units of weight  percent, within the regolith of 1 Ceres is provided as an ASCII table.  The map data are given for twenty-degree, quasi-equal-area pixels.   The data reduction and analysis methods are presented in the Supplement  of PRETTYMANETAL2017. The full-energy interaction rate of 7.6 MeV  gamma rays produced by neutron capture with Fe within Ceres' regolith  with GRaND's large-volume, bismuth germanate scintillator was  determined as a function of time while in low altitude mapping orbit  (with a mean altitude of 385 km). The counting data were corrected for  variations in the flux of galactic cosmic rays (GCR) and measurement  geometry and mapped onto 20-degree quasi-equal-area pixels. An  interpolation algorithm described by PRETTYMANETAL2017 (Supplement)  was used to determine the concentration of Fe from the gamma ray  counting data and measurements of thermal+epithermal neutrons.   The reported uncertainties are the propagated statistical uncertainty  in the Fe capture gamma ray counting data and give the  statistical precision of the Fe measurement.   Parameters  :   Each row of the table gives the concentration of hydrogen for a  single rectangular pixel.   The format for each row is '(I10,4(F7.1),2(E14.4))'.   East longitude convention is used (-180 to 180 degrees).   Each pixel spans a separate and unique portion of Vesta's surface, and  together, the pixels provide full global coverage. The BROWSE directory  displays the data as a global map. The column descriptions follow:   COLUMN NAME FORMAT DESCRIPTION UNITS  0 PIXEL_INDEX (I10) N/A  1 MIN_LAT (F7.1) Pixel latitude lower boundary deg  2 MAX_LAT (F7.1) Pixel latitude upper boundary deg  3 MIN_LON (F7.1) Pixel longitude lower boundary deg  4 MAX_LON (F7.1) Pixel longitude upper boundary deg  5 HYDROGEN_CONCENTRATION  (F8.1) Iron concentration wt.%  6 SIG_HYDROGEN_CONCENTRATION  (F8.1) Uncertainty wt.%

Confidence Level Overview  :   The data set is a high order data product derived from Fe capture gamma  and thermal + epithermal neutron counting data acquired by GRaND in  low altitude mapping orbit as described by PRETTYMANETAL2017.   Review  :   This data set is in review by NASA Planetary Data System.   Data Coverage and Quality  :   The data set contains a global map of the concentration of iron within  Ceres' regolith. There are no gaps in coverage. The depth sampled  by the gammas and neutrons used to determine Fe concentration is a few  decimeters (for example, see PRETTYMANETAL2011).   Coordinate System  :   The prime meridian is anchored by a small crater called Kait at 2 degrees  South [RUSSELLETAL2016]. East longitude convention is used.   Limitations  :   Assumptions underlying the analysis of iron in Ceres' subsurface  are presented by PRETTYMANETAL2017 (Supplement).   The analysis assumes the composition of Ceres' regolith is uniform  with depth. This assumption is valid near the equator, where water ice  is thought to be at depths greater than sensed by GRaND, and at high  latitudes, where ice is very close to the surface. The assumption  may not be valid at mid-latitudes where the ice table is within  depths sensed by GRaND.