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Voyager 2 1-hr Averaged Triaxial Fluxgate Magnetometer (MAG) Interplanetary Magnetic Field in CDF Format
var authors='Ness, Norman F.';
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(2025).
Voyager 2 1-hr Averaged Triaxial Fluxgate Magnetometer (MAG) Interplanetary Magnetic Field in CDF Format.
[Data set].
Space Physics Data Facility.
https://doi.org/10.48322/3kc2-rh71. Accessed on document.write(currentDateStr);.
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ResourceID
spase://NASA/NumericalData/Voyager2/MAG/CDF/PT1H
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 in heliographic (RTN) coordinates, and the magnetic field strength, F2, computed from 1-hr averages of the components. The vector components of B can be computed from F2 and the two angles. The elevation angle is the latitude angle above or below the solar equatorial plane, and the 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 Sci. Rev., 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.
Coordinate Systems: Interplanetary magnetic field studies make use of two important coordinate systems, the Heliographic Inertial (HGI) coordinate system and the Heliographic (HG) coordinate system.
The HGI coordinate system is used to define the spacecraft's position. The HGI system is defined with its origin at the Sun. There are three orthogonal axes, X(HGI), Y(HGI), and Z(HGI). The Z(HGI) axis points northward along the Sun's spin axis. The X(HGI)-Y(HGI) 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(HGI) axis. The X(HGI) axis drifts slowly with time, approximately one degree per 72 years.
The magnetic field orientation is defined in relation to the spacecraft. Drawing a line from the Sun's center (HGI 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(HGI)-Y(HGI) plane as well. The Z(HG) axis is chosen to complete the orthonormal triad.
An excellent reference guide with diagrams explaining the HGI and HG systems may be found in L.F. Burlaga, MHD Processes in the Outer Heliosphere, Space Sci. Rev., 39, 255-316, 1984.
Metadata Rights
CC0-1.0:
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available SPASE metadata descriptions. The actual data/software may be subject to a different license.
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Details
Version:2.7.1
NumericalData
ResourceID
spase://NASA/NumericalData/Voyager2/MAG/CDF/PT1H
NamingAuthority
NASA
ResourceType
NumericalData
ResourceHeader
ResourceName
Voyager 2 1-hr Averaged Triaxial Fluxgate Magnetometer (MAG) Interplanetary Magnetic Field in CDF Format
DOI
https://doi.org/10.48322/3kc2-rh71
ReleaseDate
2026-07-21 12:08:59Z
RevisionHistory
RevisionEvent
ReleaseDate
2020-07-07 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 18:48:04Z
Note
Added DOI. TLK
RevisionEvent
ReleaseDate
2026-06-26 13:31:23Z
Note
Add 'Z' to TemporalDescription:TimeSpan:StartDate, TemporalDescription:TimeSpan:StopDate. ZCB
RevisionEvent
ReleaseDate
2026-07-21 12:08:59Z
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 in heliographic (RTN) coordinates, and the magnetic field strength, F2, computed from 1-hr averages of the components. The vector components of B can be computed from F2 and the two angles. The elevation angle is the latitude angle above or below the solar equatorial plane, and the 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 Sci. Rev., 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.
Coordinate Systems: Interplanetary magnetic field studies make use of two important coordinate systems, the Heliographic Inertial (HGI) coordinate system and the Heliographic (HG) coordinate system.
The HGI coordinate system is used to define the spacecraft's position. The HGI system is defined with its origin at the Sun. There are three orthogonal axes, X(HGI), Y(HGI), and Z(HGI). The Z(HGI) axis points northward along the Sun's spin axis. The X(HGI)-Y(HGI) 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(HGI) axis. The X(HGI) axis drifts slowly with time, approximately one degree per 72 years.
The magnetic field orientation is defined in relation to the spacecraft. Drawing a line from the Sun's center (HGI 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(HGI)-Y(HGI) plane as well. The Z(HG) axis is chosen to complete the orthonormal triad.
An excellent reference guide with diagrams explaining the HGI and HG systems may be found in L.F. Burlaga, MHD Processes in the Outer Heliosphere, Space Sci. Rev., 39, 255-316, 1984.
Acknowledgement
Please acknowledge the Principal Investigator, Norman F. Ness of the Bartol Research Institute, University of Delaware, and the NASA National Space Science Data Center (NSSDC) for usage of data from this site in publications and presentations.
PublicationInfo
Authors
Ness, Norman 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.
MetadataContact
spase://SMWG/Person/Robert.E.McGuire
3.
MetadataContact
spase://SMWG/Person/Lee.Frost.Bargatze
InformationURL
Name
HelioData
URL
https://helio.data.nasa.gov/dataset/Voyager2_MAG_CDF_PT1H
Description
The HelioData dataset page provides an overview of the dataset with access links, associated variables, and more.
PriorIDs
spase://VSPO/NumericalData/Voyager2/MAG/CDF/PT1H
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_cdaweb/mag_1hr/
Description
In CDF via ftp from SPDF.
AccessURL
Name
HTTPS from SPDF
URL
https://spdf.gsfc.nasa.gov/pub/data/voyager/voyager2/magnetic_fields_cdaweb/mag_1hr/
Description
In CDF via http from SPDF.
Format
CDF
Encoding
None
Acknowledgement
Please acknowledge the Principal Investigator, Norman F. Ness of the Bartol Research Institute, University of Delaware, and the NASA National Space Science Data Center (NSSDC) for usage of data from this site in publications and presentations. Please acknowledge the data providers and CDAWeb when using these data.
ProcessingLevel
Calibrated
InstrumentIDs
spase://SMWG/Instrument/Voyager2/MAG
spase://SMWG/Instrument/Voyager1/Ephemeris
MeasurementType
MagneticField
TemporalDescription
TimeSpan
StartDate
1990-01-01 00:00:00.000Z
StopDate
1990-12-31 17:59:59.416Z
Cadence
PT1H
ObservedRegion
Heliosphere
ObservedRegion
Heliosphere.Outer
ObservedRegion
Heliosphere.Heliosheath
Parameter #1
Name
Time, Beginning of Interval
ParameterKey
Epoch
Description
Time, Beginning of Interval
Caveats
This parameter exhibits an increasing monotonic progression.
Cadence
PT1H
Units
ms
UnitsConversion
1e-3>s
RenderingHints
AxisLabel
Epoch
ValueFormat
E14.8
ScaleMin
6.2987652219904e+13
ScaleMax
6.3745034619904e+13
ScaleType
LinearScale
ValidMin
01-Jan-1996 00:00:00.000
ValidMax
01-Jan-2020 00:00:00.000
FillValue
-1.0e+31
Support
SupportQuantity
Temporal
Parameter #2
Name
Spacecraft Identification
Set
Time series defined by using: EPOCH
ParameterKey
Spacecraft
Description
Spacecraft Identification. 1 for Voyager 1, 2 for Voyager 2, List only
Cadence
PT1H
RenderingHints
AxisLabel
Spacecraft
ValueFormat
I1
ValidMin
1
ValidMax
2
FillValue
-128
Support
SupportQuantity
Other
Parameter #3
Name
Decimal Year
Set
Time series defined by using: EPOCH
ParameterKey
Decimal_Year
Description
Decimal Year, 90.00000 is at the Start of Day 1 for Year 1990
Cadence
PT1H
RenderingHints
DisplayType
TimeSeries
AxisLabel
Decimal Year
ValueFormat
F12.8
ValidMin
1.0
ValidMax
367.0
Support
SupportQuantity
Temporal
Parameter #4
Name
B Field Magnitude by Method 1, F1
Set
Time series defined by using: EPOCH
ParameterKey
F1Mag
Description
Magnetic Field Magnitude by Method 1, F1, 1-hr Average of High-Resolution Magnitudes
Caveats
This is the hourly time average of magnitudes from high resolution data.
Cadence
PT1H
Units
nT
UnitsConversion
1e-9>T
RenderingHints
DisplayType
TimeSeries
AxisLabel
F1 Magnitude
ValueFormat
F6.3
ValidMin
0.0
ValidMax
10.0
FillValue
999.0
Field
Qualifier
Magnitude
Qualifier
Average
FieldQuantity
Magnetic
Parameter #5
Name
Elevation Angle
Set
Time series defined by using: EPOCH
ParameterKey
elevation
Description
The Elevation Angle in Heliographic (HG) RTN Coordinates
Caveats
This is the latitude angle above or below the solar equatorial plane.
Cadence
PT1H
Units
°
UnitsConversion
0.0174532925>rad
CoordinateSystem
CoordinateRepresentation
Spherical
CoordinateSystemName
HGI
RenderingHints
DisplayType
TimeSeries
AxisLabel
elevation angle
ValueFormat
F6.1
ValidMin
-90.0
ValidMax
90.0
FillValue
999.0
Support
Qualifier
DirectionAngle.ElevationAngle
SupportQuantity
Positional
Parameter #6
Name
Azimuthal Angle
Set
Time series defined by using: EPOCH
ParameterKey
azimuth
Description
The Azimuthal Angle in Heliographic (HG) RTN Coordinates
Caveats
This is the longitude angle in the direction of orbital motion around the Sun from the Sun-to-spacecraft direction.
Cadence
PT1H
Units
°
UnitsConversion
0.0174532925>rad
CoordinateSystem
CoordinateRepresentation
Spherical
CoordinateSystemName
HGI
RenderingHints
DisplayType
TimeSeries
AxisLabel
elevation angle
ValueFormat
F6.1
ValidMin
0.0
ValidMax
360.0
FillValue
999.0
Support
Qualifier
DirectionAngle.AzimuthAngle
SupportQuantity
Positional
Parameter #7
Name
B Field Magnitude by Method 2, F2
Set
Time series defined by using: EPOCH
ParameterKey
F2Mag
Description
Magnetic Field Magnitude by Method 2, F2, 1-hr Average derived from 1-hr Averages of the B1, B2, and B3 Component Data, the value is computed by using sqrt(B1^2+B2^2+B3^2)
Caveats
The vector components are computed from F2mag and the two angles for elevation (latitude) and azimuth (longitude).
Cadence
PT1H
Units
nT
UnitsConversion
1e-9>T
RenderingHints
DisplayType
TimeSeries
AxisLabel
F1 Magnitude
ValueFormat
F6.3
ValidMin
0.0
ValidMax
10.0
FillValue
999.0
Field
Qualifier
Magnitude
Qualifier
Average
FieldQuantity
Magnetic