This is the README file for D2GMTR

D2GMTR contains the isotropic ratios of the Dynamics Explorer-2 (D2) 
Geiger-Mueller Tube (GMT) data which was generated at SwRI from the GMT 
data that was included with the LAPI VAX binary data file.  The D2GMT
data were generated by converting the VAX binary format stored at the
Space Physics Data Facility (SPDF).  The VAX binary format was converted
from the original Sigma-9 machine used to collect and process Dynamics
Explorer telemetry.  As part of the LAPI experiment, there were two
Geiger-Mueller Tubes for measuring high energy particles, one mounted
at 0 degrees (sensor 0) and the second mounted at 90 degrees (sensor 1).
The 0 deg GMT measures precipitating particles, whereas, the 90 deg GMT
measures trapped particles above the LAPI energy range.  The GMTs provide
an integral measurement.  The D2GMTR CDF files contain the ratio of the
0 deg to 90 deg (sensor 0) GMTs and the 90 deg to 0 deg (sensor 1) GMTs.
The ratio indicates how trapped or precipitating the high energy particles
are and aids in identifying the trapping boundary.  These isotropic ratios
are pure real numbers, without units attached.

GMT measurements are accumulated every second and are synchronized with
the 1 second LAPI spectral measurement cycle.  When the LAPI spectral 
measurement cycle is a multiple of 1 sec, the GMT measurement repeats to
encompass 1 second measurements within the LAPI spectral measurement cycle.
All variables are stored as 4 byte real numbers where -3.4e+38 is used to
indicate a fill value.

A status byte is included in this CDF and indicates the Status of 
processing achieved at Goddard Space Flight Center (GSFC).  

    Status  Meaning                        Number of Bits
      0     SPDF Status Flag - All               8

Each bit which makes up the status byte was extracted so that each bit
could be individually examined.  These were labeled starting at bit 0
as follows:

    Status  Meaning                        Number of Bits
      1     SPDF StatusFlag - Bit 7              1
      2     SPDF StatusFlag - Bit 6              1
      3     SPDF StatusFlag - Bit 5              1
      4     SPDF StatusFlag - Bit 4              1
      6     SPDF StatusFlag - Bit 3              1
      7     SPDF StatusFlag - Bit 2              1
      8     SPDF StatusFlag - Bit 1              1
      9     SPDF StatusFlag - Bit 0              1

The SPDF Status byte defines the processing undergone when converting 
the original DE telemetry from its Sigma-9 format to its VAX binary format.
The SPDF Status byte was meant to describe the values that were encountered 
when reading the Sigma-9 magnetic tape.  Bits 3, 6, and 7 are contained 
within Status 0.  Bit 3 indicates the SPDF Bad Sensor ID, bit 6 when the 
SPDF Previous Sensors Differs from the current sensors, and bit 7 when the 
SPDF detected a Time Gap in telemetry.  The remainder of the bits were
not defined in the SPDF documentation.  These SPDF flags are specific to 
LAPI sensor data and telemetry.

In addition two status bytes (8 bits each) are included within the CDF.  
These indicate the number of sensors sets (groups of sensors) which were 
included within a record of the LAPI VAX binary data file.  These is one 
for the 0 deg GMT and one for the 90 deg GMT.  Values are bit orientated
and there are normally 8 measurements included within the sensor set.
A bit is set to 0 when no value was reported and 1 when there was a value.
Thus, if all GMT data are available, the byte will have a value of 255.