The Venus Express (VEx) Analyzer of Space Plasmas and EneRgetic Atoms, 4th
edition (ASPERA-4) ELectron Spectrometer (ELS) Background data bundle.
This bundle was produced with funding from NASA Planetary Data Archiving, 
Restoration and Tools (PDART) 2016, grant #NNX17AL04G.

This bundle contains several collections, each of which is briefly described 
below:

document: Documents that should be considered required reading
          for this bundle. There are three documents in this collection:

      VEX_ASPERA-4_ELS_Spec - This is the Software Interface Specification
          (SIS) document. It describes the archive contents and structure,
          including file naming conventions, LID formulation, standards
          used, and details of the data products and their formats.

      VEX_ASPERA-4_ELS_Background_Data_Examples - This document explains
          background and gives an example of a background data file and
          the affect of background correction in analysis.

      VEX_ASPERA-4_ELS_Description - This document describes and gives
          full explanation of the ELS background - how the background is
          determined and how to apply background corrections. In addition,
          this document gives a full description of how to convert from
          the differential number flux units of the data in this archive
          to other physical quantities.

data_derived: This collection contains the VEx ELS derived data products,
              which includes the following:

      ELS05BK - The 5-minute averages and standard deviations of the ELS
          background per sector (16 sectors total) and the 5-minute
          average and standard deviation of the ELS anode (all sectors).
          This data product is organized as an ASCII table with 34 columns,
          16 sector averages + 16 sector standard deviations + anode
          average + anode standard deviation.

      ELSHRBCNF - The ELS High Range Background Corrected differential Number
          Flux data per sector (16 sectors total). The High Range refers to
          the ELS high energy levels given in eV. This data product is in
          ASCII Comma Separated Values (CSV) where there are 16 rows (one for
          each sector) per time period (or sweep). Nothing written between
          commas (e.g. ",,") represents a fill value.

      ELSLRBCNF - The ELS Low Range Background Corrected differential Number
          Flux data per sector (16 sectors total). The Low Range refers to
          the ELS low energy levels given in eV. This data product is in
          ASCII Comma Separated Values (CSV) where there are 16 rows (one for
          each sector) per time period (or sweep). Nothing written between
          commas (e.g. ",,") represents a fill value.

      ELSHRTHR - The ELS High Range THReshold data per sector (16 sectors
          total). This is the 1-count differential number flux threshold
          necessary to reconstruct the background corrected differential
          number flux spectrum. The High Range refers to the ELS high energy
          levels given in eV. This data product is in ASCII Comma Separated
          Values (CSV) where there are 16 rows (one for each sector) per
          time period (or sweep). Nothing written between commas (e.g. ",,")
          represents a fill value.

      ELSLRTHR - The ELS Low Range THReshold data per sector (16 sectors
          total). This is the 1-count differential number flux threshold
          necessary to reconstruct the background corrected differential
          number flux spectrum. The Low Range refers to the ELS low energy
          levels given in eV. This data product is in ASCII Comma Separated
          Values (CSV) where there are 16 rows (one for each sector) per
          time period (or sweep). Nothing written between commas (e.g. ",,")
          represents a fill value.

data_raw: This collection contains the VEx ELS raw data products, which
          includes the following:

      ELSHRCNTS - The ELS High Range raw CouNTS data per sector (16 sectors
          total). The High Range refers to the ELS high energy levels given
          in eV. This data product is in ASCII Comma Separated Values (CSV)
          where there are 16 rows (one for each sector) per time period (or
          sweep). Nothing written between commas (e.g. ",,") represents a
          fill value.

      ELSLRCNTS - The ELS Low Range raw CouNTS data per sector (16 sectors
          total). The Low Range refers to the ELS low energy levels given
          in eV. This data product is in ASCII Comma Separated Values (CSV)
          where there are 16 rows (one for each sector) per time period (or
          sweep). Nothing written between commas (e.g. ",,") represents a
          fill value.

data_eng: This collection contains the VEx ELS engineering data products
          needed for science analysis, which includes the following:

      ELSHRSTPS - The ELS High Range energy STePS in eV for each ELS sector
          (16 sectors total). These are the center energy steps (in electron
          volts, eV) at which each data value is measured per ELS sector and
          map directly to the science data (both derived and raw). This data
          product is in ASCII Comma Separated Values (CSV) where there are
          16 rows (one for each sector) per time period.

      ELSLRSTPS - The ELS Low Range energy STePS in eV for each ELS sector
          (16 sectors total). These are the center energy steps (in electron
          volts, eV) at which each data value is measured per ELS sector and
          map directly to the science data (both derived and raw). This data
          product is in ASCII Comma Separated Values (CSV) where there are
          16 rows (one for each sector) per time period.