This is the README file for MAGBLF
MAGBLF contains the Dynamics Explorer-2 (D2) MAGB instrument data, MAGB model
data, and LAPI magnetometer data presented in the frame of the LAPI instrument
(LAPI Frame - LF). The MAGB and model data were obtained from the MAGB VAX
binary data file; whereas, the LAPI magnetic field data came from the VAX
binary data file for LAPI data. These data were rotated into the LAPI frame
using the LAPI Shaft Encoder Angle. The LAPI Shaft Encoder Angle describes the
relation between the spacecraft frame and the LAPI frame. The following are
the extracted instrument values included within the MAGB LAPI Frame CDF files:
Sensor Parameter Unit valid Range
0 MAGB Measured Bx nT -65,000 to 65,000
1 MAGB Measured By nT -65,000 to 65,000
2 MAGB Measured Bz nT -65,000 to 65,000
7 Modeled Bx nT -65,000 to 65,000
8 Modeled By nT -65,000 to 65,000
9 Modeled Bz nT -65,000 to 65,000
16 LAPI Bx nT -65,000 to 65,000
17 LAPI By nT -65,000 to 65,000
18 LAPI Bz nT -65,000 to 65,000
In addition, the following items were added to the CDF file:
Sensor Parameter Unit valid Range
3 MAGB Bxy Projection nT 0 to 65,000
4 MAGB B Magnitude nT 0 to 65,000
5 MAGB Theta B deg -90 to 90
6 MAGB Phi B deg 0 to 360
10 Modeled Bxy Projection nT 0 to 65,000
11 Modeled B Magnitude nT 0 to 65,000
12 Modeled Theta B deg -90 to 90
13 Modeled Phi B deg 0 to 360
14 Measured B Pressure nPa 0 to 1.68e6
15 Modeled B Pressure nPa 0 to 1.68e6
19 LAPI Bxy Projection nT 0 to 65,000
20 LAPI B Magnitude nT 0 to 65,000
21 LAPI Theta B deg -90 to 90
22 LAPI Phi B deg 0 to 360
23 LAPI B Pressure nPa 0 to 1.68e6
Here Bxy is the magnitude Projection of the magnetic field in the x-y plane
of the LAPI instrument frame and B Magnitude is the total magnitude of the
magnetic field. The Theta B is the polar angle that the magnetic field
makes with the LAPI z axis (the same as the spacecraft z axis) and Phi B is
the azimuthal angle that the magnetic field makes with the LAPI x axis (note,
all angles are defined to be right handed). B Pressure is the magnetic
pressure computed by:
0.5 * B**2 / mu0
where mu0 = 4.0 * M_PI * 1.0e-7 and
M_PI is 3.14159265358979323846
All variables are stored as 4 byte real numbers where -3.4e+38 is used to
indicate a fill value.
Additional available units in the CDF are Gauss, Tesla, and Pascal.
No Status information is included in this CDF. The MAGBLF CDF files were
generated by converting the MAGB VAX binary format and LAPI VAX binary format
files stored at the Space Physics Data Facility (SPDF). The VAX binary format
was converted from the original Sigma-9 machine that was used to collect and
process Dynamics Explorer telemetry. The MAGB VAX binary file contained data
in the spacecraft reference frame and is rotated into the LAPI Frame via the
LAPI Shaft Encoder Angle. Both the MAGB and the LAPI magnetic field data are
stored at the cadence of the LAPI magnetic field sampling which is every two
seconds. The MAGB data is interpolated to match the LAPI magnetic field
sampling.
The LAPI magnetometer was not calibrated, so detailed analysis should not be
generated from LAPI magnetometer data. When possible, use the MAGB value for
the magnetic field.
Magnetometer values are considered instantaneous measurements. They have no
accumulation period, only data latency between measurements.