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Data Access
Voyager/MAG team site
FTPS from SPDF (not with most browsers)
HTTPS from SPDF
Voyager 2 1.92-s Averaged Triaxial Fluxgate Magnetometer (MAG) Interplanetary Magnetic Field in Binary Format
var authors='Ness, Norman F.; Burlaga, Leonard F.';
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(2025).
Voyager 2 1.92-s Averaged Triaxial Fluxgate Magnetometer (MAG) Interplanetary Magnetic Field in Binary Format.
[Data set].
Space Physics Data Facility.
https://doi.org/10.48322/v23v-rm50. Accessed on document.write(currentDateStr);.
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ResourceID
spase://NASA/NumericalData/Voyager2/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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NumericalData
ResourceID
spase://NASA/NumericalData/Voyager2/MAG/Binary/PT1.92S
NamingAuthority
NASA
ResourceType
NumericalData
ResourceHeader
ResourceName
Voyager 2 1.92-s Averaged Triaxial Fluxgate Magnetometer (MAG) Interplanetary Magnetic Field in Binary Format
DOI
https://doi.org/10.48322/v23v-rm50
ReleaseDate
2026-07-21 12:08:58Z
RevisionHistory
RevisionEvent
ReleaseDate
2021-06-02 21:15:58Z
Note
Only known prior ReleaseDate of the metadata
RevisionEvent
ReleaseDate
2025-11-14 16:03:02Z
Note
Added PublicationInfo. Added ResourceType and NamingAuthority. Changed http to https in top-level schemaLocation attribute. Fixed version number separator in top-level schemaLocation attribute. Matched version number in schemaLocation attribute to updated value in Version tag. ZCB
RevisionEvent
ReleaseDate
2025-12-04 13:32:37Z
Note
Added MetadataRightsList and RightsList(s). Updated to 2.7.1. ZCB
RevisionEvent
ReleaseDate
2026-02-17 18:48:03Z
Note
Added DOI. TLK
RevisionEvent
ReleaseDate
2026-06-26 13:31:22Z
Note
Add 'Z' to TemporalDescription:TimeSpan:StartDate, TemporalDescription:TimeSpan:StopDate. ZCB
RevisionEvent
ReleaseDate
2026-07-21 12:08:58Z
Note
Added HelioData InformationURL. JWL
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.
PublicationInfo
Authors
Ness, Norman F.; Burlaga, Leonard F.
PublicationDate
2025-11-14 16:03:02Z
PublishedBy
Space Physics Data Facility
Contacts
Role
Person
StartDate
StopDate
Note
1.
PrincipalInvestigator
spase://SMWG/Person/Norman.F.Ness
2.
CoInvestigator
spase://SMWG/Person/Leonard.F.Burlaga
InformationURL
Name
Readme at Voyager MAG team web site
URL
https://vgrmag-data.gsfc.nasa.gov/pub/data/voyager/vgrmag-data/summary/readme.summary
InformationURL
Name
as defined for the original VMS binary format
URL
https://spdf.gsfc.nasa.gov/pub/data/voyager/voyager2/magnetic_fields/ip_summary_vmsbin/voysum.txt
Description
Detailed Description of Variables
InformationURL
Name
HelioData
URL
https://helio.data.nasa.gov/dataset/Voyager2_MAG_Binary_PT1.92S
Description
The HelioData dataset page provides an overview of the dataset with access links, associated variables, and more.
PriorIDs
spase://VSPO/NumericalData/P_VOYAGER2_HDR_MAG_1.92S_BIN
sspase://VSPO/NumericalData/Voyager2/MAG/PT1.92S
spase://VSPO/NumericalData/Voyager2/MAG/Binary/PT1.92S
AccessInformation
RepositoryID
spase://SMWG/Repository/NASA/GSFC/Voyager/MAG
Availability
Online
AccessRights
Open
RightsList
Rights
SchemeURI
https://spdx.org/licenses/
RightsIdentifierScheme
SPDX
RightsIdentifier
CC0-1.0
RightsURI
https://spdx.org/licenses/CC0-1.0.html
RightsName
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available NASA Heliophysics data products
AccessURL
Name
Voyager/MAG team site
URL
https://vgrmag-data.gsfc.nasa.gov/pub/data/voyager/vgrmag-data/summary/v2/
Format
Text
AccessInformation
RepositoryID
spase://SMWG/Repository/NASA/GSFC/SPDF
Availability
Online
AccessRights
Open
RightsList
Rights
SchemeURI
https://spdx.org/licenses/
RightsIdentifierScheme
SPDX
RightsIdentifier
CC0-1.0
RightsURI
https://spdx.org/licenses/CC0-1.0.html
RightsName
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available NASA Heliophysics data products
AccessURL
Name
FTPS from SPDF (not with most browsers)
URL
ftps://spdf.gsfc.nasa.gov/pub/data/voyager/voyager2/magnetic_fields/ip_summary_vmsbin/
Description
In binary via FTP from SPDF
AccessURL
Name
HTTPS from SPDF
URL
https://spdf.gsfc.nasa.gov/pub/data/voyager/voyager2/magnetic_fields/ip_summary_vmsbin/
Description
In binary via HTTP from SPDF
Format
Binary
ProviderProcessingLevel
CALIBRATED
InstrumentIDs
spase://SMWG/Instrument/Voyager2/MAG
MeasurementType
MagneticField
TemporalDescription
TimeSpan
StartDate
1977-08-20 15:57:30Z
StopDate
1991-01-01 00:01:09Z
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