Document title: Readme.doc for NDADS DE-2 VEFIMAGB datatype: VEFI and MAGB
merged data 
Project: DE 
NDADS Datatype: VEFIMAGB                
Super-EID: DOCUMENT                      
There may be other documents also identified by this super-EID.
NDADS filename: VEFIMAGB_README.DOC
TRF entry B46572.txt in NSSDC's controlled digital document library. Feb. 1998.
Document text follows:
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   DYNAMICS EXPLORER 2 (DE-2) VECTOR ELECTRIC FIELD INSTRUMENT (VEFI) AND
                    MAGNETOMETER (MAGB) MERGED DATA BASE


This data set is a combination of the VEFI and MAGB high resolution data sets
in SPC coordinates submitted to NSSDC.  The following OA parameters have been 
added to the data set:  Model magnetic field in SPC coordinates, altitude of
the satellite, geographic latitude and longitude, magnetic local time, and
invariant latitude.

The VEFI data set is described in the file VEFIVOLDESC.SFD and the MAGB data set
is described in the file MAGBVOLDESC.SFD, these files are portions of the SFDU
metadata files submitted with the VEFI and MAGB data to NSSDC and are included
in each volume of this data set.

This data set consists of daily files from day 81227 to day 83047.  Each file 
contains all the data available for a given day.  During the merging of the 
data sets it was found that although VEFI and MAGB should cover the same 
time spans, they do not, due perhaps to the fact that the original MAGB high 
resolution data set was created on the DE Sigma-9 using the DE telemetry tapes, 
while the VEFI high resolution data set was created on the DE MicroVAX system 
using the DE telemetry data base on optical disk.  In order to keep the largest 
amount of data possible, the merged data set includes all the available VEFI 
and MAGB data, for those times when VEFI data was available but MAGB was not 
(6.54%), a fill data value of 9999999. was given to the MAGB data and for 
those times when MAGB data was available but VEFI was not (6.87%), the fill 
data value was assigned to the VEFI data.  Times for which both VEFI and MAGB 
data were fill values in the original data sets were not included in the merged 
data set.  There were also times when certain OA parameters were fill values in
the OA data base and they are therefore also fill values in this merged data 
set.  The model magnetic field had fill values for 8.55% of the data.  Statistics 
were not kept for the other OA parameters. 

Each daily file contains a record per measurement.  The total number of records
in each file varies depending on the amount of data available for a given day.
Each record of each daily file contains the following information:

VTIME    Integer*4    Time of the VEFI measurement in tenths of milliseconds
EX       Real*4       X-Component of the VEFI electric field in SPC coordinates
EY       Real*4       Y-Component of the VEFI electric field in SPC coordinates
MTIME    Integer*4    Time of the MAGB measurement in tenths of milliseconds
BX       Real*4       X-Component of the MAGB magnetic field in SPC coordinates
BY       Real*4       Y-Component of the MAGB magnetic field in SPC coordinates
BZ       Real*4       Z-Component of the MAGB magnetic field in SPC coordinates
BXM      Real*4       X-Component of the model magnetic field in SPC coordinates
BYM      Real*4       Y-Component of the model magnetic field in SPC coordinates
BZM      Real*4       Z-Component of the model magnetic field in SPC coordinates
ALT      Real*4       Altitude of the satellite
GLAT     Real*4       Geographic Latitude
GLONG    Real*4       Geographic Longitude
MLT      Real*4       Magnetic Local Time
ILAT     Real*4       Invariant Latitude

Each record was writen in VAX binary and can be read in VAX fortran using the
following statement: 

     READ(UNIT) VTIME,EX,EY,MTIME,BX,BY,BZ,BXM,BYM,BZM,ALT,GLAT,GLONG,MLT,ILAT

Care must be taken to declare VTIME as integer*4 and MLT and ILAT as real*4