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Voyager 1 1.92-s Averaged Triaxial Fluxgate Magnetometer (MAG) Interplanetary Magnetic Field in Binary Format

ResourceID
spase://NASA/NumericalData/Voyager1/MAG/Binary/PT1.92S

Description

This data set includes the Voyager spacecraft number (1 or 2), the date-time in
decimal year (90.00000 is day 1 of 1990), the magnetic field strength F1
computed from high-resolution magnitudes, the elevation and azimuth angles
(degrees) in heliographic (RTN) coordinates, and the magnetic field strength F2
computed from hour averages of the components. The vector components of B can be
computed from F2 and the two angles. Elevation angle is the latitude angle above
or below the solar equatorial plane, and azimuth angle is in the direction
orbital motion around the Sun from the projection of the Sun-to-spacecraft axis
into the solar equatorial plane. The Voyager MAG experiment and coordinates are
further described in the following publication: Behannon, K.W., M.H. Acuna,
L.F. Burlaga, R.P. Lepping, N.F. Ness, and F.M. Neubauer, Magnetic-Field
Experiment for Voyager-1 and Voyager-2, Space Science Reviews, 21 (3), 235-257,
1977...At the time of experiment proposal, it was expected that the required
accuracy of the measurements would be 0.1 nT, determined by the combined noise
of the sensors and the spacecraft field. The spacecraft magnetic field at the
outboard magnetic field sensor, referred to as the primary unit, was expected to
be 0.2 nT and highly variable, consistent with current estimates. Hence, the
dual magnetometer design (Ness et al., 1971, 1973; Behannon et al. 1977). ..At
distances > 40 AU, the heliospheric magnetic fields are generally much weaker
than 0.4 nT; the average magnetic field strength near 40 AU and 85 AU is about
0.15 nT and 0.05 nT, respectively. The use of roll calibrations lasting about 6
hours permits determination of the effective zero levels for the two independent
magnetic axes that are perpendicular to the roll axis (which is nearly parallel
to the radius vector to the Sun) at intervals of about 3 months. There is no
roll calibration for the third magnetic axis. Comparison of the two derived
magnetic vectors from the two magnetometers permits validation of the primary
magnetometer data with an accuracy of 0.02 to 0.05 nT. A discussion of the
uncertainties that must be considered when using these data is given in the
Appendix of Burlaga et al. [1994] and in Appendix A of Burlaga et al. [2002].
..References: ..Behannon, K.W., M.H. Acuna, L.F. Burlaga, R.P. Lepping, N.F.
Ness, and F.M. Neubauer, Magnetic-Field Experiment for Voyager-1 and Voyager-2,
Space Science Reviews, 21 (3), 235-257, 1977. ..Burlaga, L.F., Merged
interaction regions and large-scale magnetic field fluctuations during 1991 -
Voyager-2 observations, J. Geophys. Res., 99 (A10), 19341-19350, 1994.
..Burlaga, L.F., N.F. Ness, Y.-M. Wang, and N.R. Sheeley Jr., Heliospheric
magnetic field strength and polarity from 1 to 81 AU during the ascending phase
of solar cycle 23, J. Geophys. Res., 107 (A11), 1410, 2002. ..Ness, N., K.W.
Behannon, R. Lepping, and K.H. Schatten, J. Geophys. Res., 76, 3564, 1971.
..Ness et al., 1973
At distances > 40 AU, the heliospheric magnetic fields are generally much weaker
than 0.4 nT; the average magnetic field strength near 40 AU and 85 AU is about
0.15 nT and 0.05 nT, respectively. The use of roll calibrations lasting about 6
hours permits determination of the effective zero levels for the two independent
magnetic axes that are perpendicular to the roll axis (which is nearly parallel
to the radius vector to the Sun) at intervals of about 3 months. There is no
roll calibration for the third magnetic axis. Comparison of the two derived
magnetic vectors from the two magnetometers permits validation of the primary
magnetometer data with an accuracy of 0.02 to 0.05 nT. A discussion of the
uncertainties that must be considered when using these data is given in the
Appendix of Burlaga et al. [1994] and in Appendix A of Burlaga et al. [2002].
COORDINATE SYSTEMS: Interplanetary magnetic field studies make use of two
important coordinate systems, the Inertial Heliographic (IHG) coordinate system
and the Heliographic (HG) coordinate system.
The IHG coordinate system is use to define the spacecraft's position. The IHG
system is defined with its origin at the Sun. There are three orthogonal axes,
X(IHG), Y(IHG), and Z(IHG). The Z(IHG) axis points northward along the Sun's
spin axis. The X(IHG) - Y(IHG) plane lays in the solar equatorial plane. The
intersection of the solar equatorial plane with the ecliptic plane defines a
line, the longitude of the ascending node, which is taken to be the X(IHG) axis.
The X(IHG) axis drifts slowly with time, approximately one degree per 72 years.
Magnetic field orientation is defined in relation to the spacecraft. Drawing a
line from the Sun's center (IHG origin) to the spacecraft defines the X axis of
the HG coordinate system. The HG coordinate system is defined with its origin
centered at the spacecraft. Three orthogonal axes are defined, X(HG), Y(HG),
and Z(HG). The X(HG) axis points radially away from the Sun and the Y(HG) axis
is parallel to the solar equatorial plane and therefore parallel to the
X(IHG)-Y(IHG) plane too. The Z(HG) axis is chosen to complete the orthonormal
triad.
An excellent reference guide with diagrams explaining the IHG and HG systems may
be found in Space and Science Reviews, Volume 39 (1984), pages 255-316, MHD
Processes in the Outer Heliosphere, L. F. Burlaga.

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Version:2.3.0

NumericalData

ResourceID
spase://NASA/NumericalData/Voyager1/MAG/Binary/PT1.92S
ResourceHeader
ResourceName
Voyager 1 1.92-s Averaged Triaxial Fluxgate Magnetometer (MAG) Interplanetary Magnetic Field in Binary Format
ReleaseDate
2021-06-02 21:15:53Z
Description

This data set includes the Voyager spacecraft number (1 or 2), the date-time in
decimal year (90.00000 is day 1 of 1990), the magnetic field strength F1
computed from high-resolution magnitudes, the elevation and azimuth angles
(degrees) in heliographic (RTN) coordinates, and the magnetic field strength F2
computed from hour averages of the components. The vector components of B can be
computed from F2 and the two angles. Elevation angle is the latitude angle above
or below the solar equatorial plane, and azimuth angle is in the direction
orbital motion around the Sun from the projection of the Sun-to-spacecraft axis
into the solar equatorial plane. The Voyager MAG experiment and coordinates are
further described in the following publication: Behannon, K.W., M.H. Acuna,
L.F. Burlaga, R.P. Lepping, N.F. Ness, and F.M. Neubauer, Magnetic-Field
Experiment for Voyager-1 and Voyager-2, Space Science Reviews, 21 (3), 235-257,
1977...At the time of experiment proposal, it was expected that the required
accuracy of the measurements would be 0.1 nT, determined by the combined noise
of the sensors and the spacecraft field. The spacecraft magnetic field at the
outboard magnetic field sensor, referred to as the primary unit, was expected to
be 0.2 nT and highly variable, consistent with current estimates. Hence, the
dual magnetometer design (Ness et al., 1971, 1973; Behannon et al. 1977). ..At
distances > 40 AU, the heliospheric magnetic fields are generally much weaker
than 0.4 nT; the average magnetic field strength near 40 AU and 85 AU is about
0.15 nT and 0.05 nT, respectively. The use of roll calibrations lasting about 6
hours permits determination of the effective zero levels for the two independent
magnetic axes that are perpendicular to the roll axis (which is nearly parallel
to the radius vector to the Sun) at intervals of about 3 months. There is no
roll calibration for the third magnetic axis. Comparison of the two derived
magnetic vectors from the two magnetometers permits validation of the primary
magnetometer data with an accuracy of 0.02 to 0.05 nT. A discussion of the
uncertainties that must be considered when using these data is given in the
Appendix of Burlaga et al. [1994] and in Appendix A of Burlaga et al. [2002].
..References: ..Behannon, K.W., M.H. Acuna, L.F. Burlaga, R.P. Lepping, N.F.
Ness, and F.M. Neubauer, Magnetic-Field Experiment for Voyager-1 and Voyager-2,
Space Science Reviews, 21 (3), 235-257, 1977. ..Burlaga, L.F., Merged
interaction regions and large-scale magnetic field fluctuations during 1991 -
Voyager-2 observations, J. Geophys. Res., 99 (A10), 19341-19350, 1994.
..Burlaga, L.F., N.F. Ness, Y.-M. Wang, and N.R. Sheeley Jr., Heliospheric
magnetic field strength and polarity from 1 to 81 AU during the ascending phase
of solar cycle 23, J. Geophys. Res., 107 (A11), 1410, 2002. ..Ness, N., K.W.
Behannon, R. Lepping, and K.H. Schatten, J. Geophys. Res., 76, 3564, 1971.
..Ness et al., 1973
At distances > 40 AU, the heliospheric magnetic fields are generally much weaker
than 0.4 nT; the average magnetic field strength near 40 AU and 85 AU is about
0.15 nT and 0.05 nT, respectively. The use of roll calibrations lasting about 6
hours permits determination of the effective zero levels for the two independent
magnetic axes that are perpendicular to the roll axis (which is nearly parallel
to the radius vector to the Sun) at intervals of about 3 months. There is no
roll calibration for the third magnetic axis. Comparison of the two derived
magnetic vectors from the two magnetometers permits validation of the primary
magnetometer data with an accuracy of 0.02 to 0.05 nT. A discussion of the
uncertainties that must be considered when using these data is given in the
Appendix of Burlaga et al. [1994] and in Appendix A of Burlaga et al. [2002].
COORDINATE SYSTEMS: Interplanetary magnetic field studies make use of two
important coordinate systems, the Inertial Heliographic (IHG) coordinate system
and the Heliographic (HG) coordinate system.
The IHG coordinate system is use to define the spacecraft's position. The IHG
system is defined with its origin at the Sun. There are three orthogonal axes,
X(IHG), Y(IHG), and Z(IHG). The Z(IHG) axis points northward along the Sun's
spin axis. The X(IHG) - Y(IHG) plane lays in the solar equatorial plane. The
intersection of the solar equatorial plane with the ecliptic plane defines a
line, the longitude of the ascending node, which is taken to be the X(IHG) axis.
The X(IHG) axis drifts slowly with time, approximately one degree per 72 years.
Magnetic field orientation is defined in relation to the spacecraft. Drawing a
line from the Sun's center (IHG origin) to the spacecraft defines the X axis of
the HG coordinate system. The HG coordinate system is defined with its origin
centered at the spacecraft. Three orthogonal axes are defined, X(HG), Y(HG),
and Z(HG). The X(HG) axis points radially away from the Sun and the Y(HG) axis
is parallel to the solar equatorial plane and therefore parallel to the
X(IHG)-Y(IHG) plane too. The Z(HG) axis is chosen to complete the orthonormal
triad.
An excellent reference guide with diagrams explaining the IHG and HG systems may
be found in Space and Science Reviews, Volume 39 (1984), pages 255-316, MHD
Processes in the Outer Heliosphere, L. F. Burlaga.

Contacts
RolePersonStartDateStopDateNote
1.PrincipalInvestigatorspase://SMWG/Person/Norman.F.Ness
2.CoInvestigatorspase://SMWG/Person/Leonard.F.Burlaga
InformationURL
InformationURL
Name
as defined for the original VMS binary format
URL
Description

Detailed Description of Variables

PriorIDs
spase://VSPO/NumericalData/P_VOYAGER1_HDR_MAG_1.92S_BIN
sspase://VSPO/NumericalData/Voyager1/MAG/PT1.92S
spase://VSPO/NumericalData/Voyager1/MAG/Binary/PT1.92S
AccessInformation
RepositoryID
Availability
Online
AccessRights
Open
AccessURL
Format
Text
AccessInformation
RepositoryID
Availability
Online
AccessRights
Open
AccessURL
Name
FTPS from SPDF (not with most browsers)
URL
Description

In binary via FTP from SPDF

AccessURL
Name
HTTPS from SPDF
URL
Description

In binary via HTTP from SPDF

Format
Binary
ProviderProcessingLevel
CALIBRATED
InstrumentIDs
MeasurementType
MagneticField
TemporalDescription
TimeSpan
StartDate
1977-09-05 14:19:47
StopDate
1991-12-27 00:00:42
Cadence
PT1.92S
ObservedRegion
Heliosphere.Outer
ObservedRegion
Heliosphere.Heliosheath
Caveats
Extracting the signal describing the solar wind and heliosheath from the many sources of uncertainty is a complex and partly subjective process that requires understanding of the instrument and judgment based on experience in dealing with the ever-changing extraneous signals. As a result, users should consult the specific caveats that are included in the header of each granule. The granule headers list any caveats that are specific to that time interval.
Parameter #1
Name
Spacecraft ID
ParameterKey
Column_1
Description

Spacecraft ID. Value FLT1 means Voyager 1.

Support
SupportQuantity
Other
Parameter #2
Name
Coordinate system
ParameterKey
Column_2
Description

Flag for coordinate system. Virtually all values are HG,
meaning Heliographic Inertial

Support
SupportQuantity
Other
Parameter #3
Name
Year
ParameterKey
Column_3
Description

Year of the measurement, 2 digits

Support
SupportQuantity
Temporal
Parameter #4
Name
Day of year
ParameterKey
Column_4
Description

Fractional day of year of the measurement (Jan 1 = 1).

ValidMin
1
ValidMax
366.9999
Support
SupportQuantity
Temporal
Parameter #5
Name
B
ParameterKey
Column_5
Description

The magnetic field strength, the average of higher resolution field strengths, in nT

Units
nT
Field
Qualifier
Magnitude
Qualifier
Average
FieldQuantity
Magnetic
Parameter #6
Name
Magnitude average
ParameterKey
Column_6
Description

Magnitude of vector constituted by average field components

Units
nT
Field
Qualifier
Magnitude
Qualifier
Average
FieldQuantity
Magnetic
Parameter #7
Name
Field elevation angle
ParameterKey
Column_7
Description

Elevation angle of magnetic field vector

Units
Deg
CoordinateSystem
CoordinateRepresentation
Spherical
CoordinateSystemName
RTN
ValidMin
-90.
ValidMax
90.
Field
Qualifier
DirectionAngle.ElevationAngle
Qualifier
Average
FieldQuantity
Magnetic
Parameter #8
Name
Field azimuth angle
ParameterKey
Column_8
Description

Azimuth angle of magnetic field vector

Units
Deg
CoordinateSystem
CoordinateRepresentation
Spherical
CoordinateSystemName
RTN
ValidMin
0.
ValidMax
360.
Field
Qualifier
DirectionAngle.AzimuthAngle
Qualifier
Average
FieldQuantity
Magnetic
Parameter #9
Name
Br
ParameterKey
Column_9
Description

Radial component of vector magnetic field in RTN coordinates.

Units
nT
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
RTN
Field
Qualifier
Component.I
Qualifier
Average
FieldQuantity
Magnetic
Parameter #10
Name
Bt
ParameterKey
Column_10
Description

Transverse component of vector magnetic field in RTN coordinates

Units
nT
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
RTN
Field
Qualifier
Component.J
Qualifier
Average
FieldQuantity
Magnetic
Parameter #11
Name
Bn
ParameterKey
Column_11
Description

Normal component of vector magnetic field in RTN coordinates

Units
nT
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
RTN
Field
Qualifier
Component.K
Qualifier
Average
FieldQuantity
Magnetic
Parameter #12
Name
dBr
ParameterKey
Column_12
Description

1-sigma uncertainty in the radial component of vector magnetic field in RTN coordinates.

Units
nT
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
RTN
Field
Qualifier
Component.I
Qualifier
StandardDeviation
FieldQuantity
Magnetic
Parameter #13
Name
dBt
ParameterKey
Column_13
Description

1-sigma uncertainty in the transverse component of vector magnetic field in RTN coordinates

Units
nT
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
RTN
Field
Qualifier
Component.J
Qualifier
StandardDeviation
FieldQuantity
Magnetic
Parameter #14
Name
dBn
ParameterKey
Column_14
Description

1-sigma uncertainty in the normal component of vector magnetic field in RTN coordinates

Units
nT
UnitsConversion
1e-9>T
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
RTN
Field
Qualifier
Component.K
Qualifier
StandardDeviation
FieldQuantity
Magnetic
Parameter #15
Name
X
ParameterKey
Column_15
Description

X component of HGI spacecraft position vector.

Units
AU
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
HGI
Support
Qualifier
Component.I
SupportQuantity
Positional
Parameter #16
Name
Y
ParameterKey
Column_16
Description

Y component of HGI spacecraft position vector.

Units
AU
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
HGI
Support
Qualifier
Component.J
SupportQuantity
Positional
Parameter #17
Name
Z
ParameterKey
Column_17
Description

Z component of HGI spacecraft position vector.

Units
AU
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
HGI
Support
Qualifier
Component.K
SupportQuantity
Positional
Parameter #18
Name
R
ParameterKey
Column_18
Description

Heliocentric radial distance of spacecraft.

Units
AU
Support
SupportQuantity
Positional