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CDAWeb Served Heliophysics Datasets Beginning with 'V'

VENUS_HELIO1DAY_POSITION: Position in heliocentric coordinates from SPDF Helioweb - Natalia Papitashvili (NASA/GSFC/SPDF)
VG1_PWS_LR: Lowrate Plasma Waves Instrument - William Kurth (University of Iowa)
VG1_PWS_WF: Voyager 1, Plasma Waves Science, Wideband Electric Waveforms - W. Kurth (University Iowa)
VG2_PWS_LR: Lowrate Plasma Waves Instrument - William Kurth (University of Iowa)
VG2_PWS_WF: Voyager 2, Plasma Waves Science, Wideband Electric Waveforms - W. Kurth (University Iowa)
VOYAGER-1_LECP_ELEC-BGND-COR-1D: Voyager 1 LECP Background-corrected electron differential fluxes - Rob Decker (The John Hopkins Applied Physics Laboratory)
VOYAGER-2_LECP_ELEC-BGND-COR-1D: voyager 2 LECP Background-corrected electron differential fluxes - Rob Decker (The John Hopkins Applied Physics Laboratory)
VOYAGER1_10S_MAG: 9.6 Second Averaged Interplanetary Magnetic Field - Norman F. Ness (Bartol Research Institute)
VOYAGER1_2S_MAG: 1.92 Second Averaged Interplanetary Magnetic Field - Norman F. Ness (Bartol Research Institute)
VOYAGER1_48S_MAG: 48 second interplanetary magnetic field - Norman F. Ness (Bartol Research Institute)
VOYAGER1_48S_MAG-VIM: Voyager1 Magnetic field VIM - Len Burlaga (NASA/GSFC)
VOYAGER1_COHO1HR_MERGED_MAG_PLASMA: Merged hourly magnetic field, plasma, proton fluxes, and ephemeris data - Norman F. Ness (Bartol Research Institute)
VOYAGER1_CRS_DAILY_FLUX: Voyager-1 CRS Daily Averaged Flux - E. C. Stone (California Institute of Technology)
VOYAGER1_HELIO1DAY_POSITION: Position in heliocentric coordinates from SPDF Helioweb - Natalia Papitashvili (NASA/GSFC/SPDF)
VOYAGER1_PLS_COMPOSITION: Voyager1, VIPER-Fit Plasma Ion Composition near Jupiter - Dr. John D. Richardson (MIT Kavli Institute)
VOYAGER1_PLS_ELECTRONS_E1: Voyager-1 Jupiter Low-Energy Electron Current Spectra - Dr. John D. Richardson (MIT Kavli Institute)
VOYAGER1_PLS_ELECTRONS_E2: Voyager-1 Jupiter Low-Energy Electron Current Spectra - Dr. John D. Richardson (MIT Kavli Institute)
VOYAGER1_PLS_HIRES_PLASMA_DATA: HiRes plasma data - John D. Richardson (Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology.)
VOYAGER1_PLS_IONS_L: Voyager-1 Jupiter Low-Resolution Ion Current Spectra - Dr. John D. Richardson (MIT Kavli Institute)
VOYAGER1_PLS_IONS_M: Voyager-1 Jupiter Low-Resolution Ion Current Spectra - Dr. John D. Richardson (MIT Kavli Institute)
VOYAGER2_10S_MAG: 9.6 second interplanetary magnetic field - Norman F. Ness (Bartol Research Institute)
VOYAGER2_2S_MAG: 9.6 second interplanetary magnetic field - Norman F. Ness (Bartol Research Institute)
VOYAGER2_48S_MAG: 48 second interplanetary magnetic field - Norman F. Ness (Bartol Research Institute)
VOYAGER2_48S_MAG-VIM: Voyager2 Magnetic field VIM - Len Burlaga (NASA/GSFC)
VOYAGER2_COHO1HR_MERGED_MAG_PLASMA: Voyager-2 merged hourly magnetic field, plasma, proton fluxes, and ephemeris data - N. Ness (MAG) and J. Richardson (PLS) (Bartol, MIT)
VOYAGER2_HELIO1DAY_POSITION: Position in heliocentric coordinates from SPDF Helioweb - Natalia Papitashvili (NASA/GSFC/SPDF)
VOYAGER2_PLS_COMPOSITION: Voyager1, VIPER-Fit Plasma Ion Composition near Jupiter - Dr. John D. Richardson (MIT Kavli Institute)
VOYAGER2_PLS_ELECTRONS_E1: Voyager-1 Jupiter Low-Energy Electron Current Spectra - Dr. John D. Richardson (MIT Kavli Institute)
VOYAGER2_PLS_ELECTRONS_E2: Voyager-1 Jupiter Low-Energy Electron Current Spectra - Dr. John D. Richardson (MIT Kavli Institute)
VOYAGER2_PLS_HIRES_PLASMA_DATA: HiRes plasma data - John D. Richardson (Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology.)
VOYAGER2_PLS_HIRES_PLASMA_DATA_HSH: Voyager 2 high resolution plasma data in the heliosheath - John D. Richardson (Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology)
VOYAGER2_PLS_IONS_L: Voyager-1 Jupiter Low-Resolution Ion Current Spectra - Dr. John D. Richardson (MIT Kavli Institute)
VOYAGER2_PLS_IONS_M: Voyager-1 Jupiter Low-Resolution Ion Current Spectra - Dr. John D. Richardson (MIT Kavli Institute)
VENUS_HELIO1DAY_POSITION (spase://NASA/NumericalData/Planet/Venus/HelioWeb/Ephemeris/P1D)
Description
No TEXT global attribute value.
Dataset in CDAWeb
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VG1_PWS_LR (spase://NASA/NumericalData/Voyager1/PWS/CDF/PT4S)
Description
The data set overview 
can be found at 
https://space.physics.uiowa.edu/plasma-wave/voyager/data/voyager-1-pws-sa/docume
nt/FULL1_DS.TXT
F. L. Scarf and D. A. Gurnett, A Plasma Wave Investigation  for the Voyager
Mission,  Space Sci. Rev., 21, 289,  1977. 
https://space.physics.uiowa.edu/voyager/
Dataset in CDAWeb
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VG1_PWS_WF (https://doi.org/10.17189/g5fy-rz59)
Description
'A Plasma Wave Investigation for the Voyager Mission' F. L. Scarf and D. A.
Gurnett, Space Science Reviews, Vol. 21, p. 289, 1977.
Dataset in CDAWeb
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VG2_PWS_LR (spase://NASA/NumericalData/Voyager2/PWS/CDF/PT4S)
Description
The data set overview 
can be found at 
https://space.physics.uiowa.edu/plasma-wave/voyager/data/voyager-2-pws-sa/docume
nt/FULL2_DS.TXT
F. L. Scarf and D. A. Gurnett, A Plasma Wave Investigation  for the Voyager
Mission,  Space Sci. Rev., 21, 289,  1977. 
https://space.physics.uiowa.edu/voyager/
Dataset in CDAWeb
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VG2_PWS_WF (https://doi.org/10.17189/bwn5-bs17)
Description
'A Plasma Wave Investigation for the Voyager Mission' F. L. Scarf and D. A.
Gurnett, Space Science Reviews, Vol. 21, p. 289, 1977.
Dataset in CDAWeb
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VOYAGER-1_LECP_ELEC-BGND-COR-1D
Description
This data set contains data from the LECP instrument on the Voyager 1
spacecraft. Each record in a file contains 1-day (24-hour) scan-averaged fluxes
and flux uncertainties of electrons in two contiguous energy channels that cover
the energy range 26-70 keV. The period 2002/001 through 2012/240 includes
electrons measured upstream of the termination shock and in the heliosheath up
though ~2 days after the heliopause crossing. The Voyager 1 LECP instrument
steps through eight, 45 deg full-angle sectors, spending 192 sec in each sector,
yielding a full scan through 360 deg every 25.6 min. The LECP scan plane is
nearly parallel to RT-plane of the heliospheric RTN coordinate system. The
electron data are averaged over the seven active sectors S1-S7; S8 is behind the
sun-shield and not included in the average.
-- Electron channels designated EB01 and EB02
-- Data have been corrected to remove background due to penetrating cosmic ray
ions 
-- Fluxes and uncertainties (one st. dev.) in units: electrons/cm^2-s-sr-MeV
-- Data are 5-point running averages of daily values
-- Values -9.900e+01 used for missing or nonphysical data 
-- Negative year indicates filled data for the associated doy
Dataset in CDAWeb
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VOYAGER-2_LECP_ELEC-BGND-COR-1D
Description
This data set contains data from the LECP instrument on the Voyager 2
spacecraft. Each record in a file contains 1-day (24-hour) scan-averaged fluxes
and flux uncertainties of electrons in two contiguous energy channels that cover
the energy range 22-61 keV. The period 2006/001 through 2018/304 includes
electrons measured upstream of the termination shock and in the heliosheath up
to heliopause crossing. The voyager 2 LECP instrument steps through eight, 45
deg full-angle sectors, spending 192 sec in each sector, yielding a full scan
through 360 deg every 25.6 min. The LECP scan plane is nearly parallel to
RT-plane of the heliospheric RTN coordinate system. The electron data are
averaged over the seven active sectors S1-S7; S8 is behind the sun-shield and
not included in the average.
-- Electron channels designated EB01 and EB02
-- Data have been corrected to remove background due to penetrating cosmic ray
ions 
-- Fluxes and uncertainties (one st. dev.) in units: electrons/cm^2-s-sr-MeV
-- Data are 5-point running averages of daily values
-- Values -9.900e+01 used for missing or nonphysical data 
-- Negative year indicates filled data for the associated doy
Dataset in CDAWeb
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VOYAGER1_10S_MAG (spase://NASA/NumericalData/Voyager1/MAG/CDF/PT9.6S)
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.
Dataset in CDAWeb
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VOYAGER1_2S_MAG (spase://NASA/NumericalData/Voyager1/MAG/CDF/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.
Dataset in CDAWeb
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VOYAGER1_48S_MAG (spase://NASA/NumericalData/Voyager1/MAG/CDF/PT48S)
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.
Support data calib_flag_on, calib_flag_MF and calib_flag_offset are added to
file version 2. Variable calib_flag_on consists of points where bit 4 or 5 in
variable magStatus equal 1. Variable calib_flag_MF represents observations where
magnetometer was in cailbration mode. Variable calib_flag_offset represent delay
between data points where magnetometer was in calibration mode and data points
where magStatus variable indicated calibration periods.Due to specific shape of
magnetometer data profile variable calibration_flag_MF may cover larger
intervals than calibration_flag_on.
Dataset in CDAWeb
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VOYAGER1_48S_MAG-VIM (spase://NASA/NumericalData/Voyager1/MAG/VIM/CDF/PT48S)
Description
The  main science objectives for the VOYAGER interplanetary mission are as  
follows: 
- investigate the structure of the solar wind magnetic fields and plasma in the
inner and outer heliosphere; 
- conduct long term study of heliospheric evolution during different phases of
the twenty-two year solar magnetic cycle and the eleven-year solar activity
cycle;
- study the long term solar modulation and determine the elemental and isotopic
abundances of galactic cosmic ray particles in the heliosphere;
- measure  radial gradients, spectra, and nuclear abundances of the anomalous
component of cosmic rays  from  acceleration at the solar wind termination
shock; 
- investigate local particle acceleration in the interplanetary medium from
solar flare shocks and corotating interaction regions; 
- study propagation of solar energetic particles in the heliosphere.
The average magnetic field strength produced by the spacecraft at the location
of the outboard magnetometer of the dual magnetometers system on V1 and V2 is
about 0.1 - 0.2 nT, comparable to the most probable magnetic field strength in
the inner heliosheath and significantly larger than the most probable magnetic
field strength in the distant supersonic solar wind. The spacecraft magnetic
field is a complex, time-dependent signal that must be removed from the measured
magnetic field signal in order to derive the ambient magnetic fields of the
solar wind and heliosheath. Corrections must also be made for spurious magnetic
signals and noise associated with the telemetry system, ground tracking systems,
and other factors. 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. We
estimate that for the V1 MAG data the 1-sigma the uncertainty the 48 sec
averages for each of the components of the magnetic field  BR, BT, and BN is
typically +/- 0.02 nT; the uncertainty in magnitude F1 is typically +/- 0.03 nT.
F1, BR, BT, and BN can differ from one another and they may vary with time, but
there is no practical way to determine these uncertainties more precisely at
present.
References
Daniel B. Berdichevsky, Voyager Mission, Detailed processing of weak magnetic
fields; I - Constraints to the uncertainties of the calibrated magnetic field
signal in the Voyager missions , 2009;
https://vgrmag.gsfc.nasa.gov/Berdichevsky-VOY_sensor_opu090518.pdf
Behannon, K.W., M.H. Acu..a, 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.
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VOYAGER1_COHO1HR_MERGED_MAG_PLASMA (spase://NASA/NumericalData/Voyager1/MAGandPLS/PT1H)
Description
The  main science objectives for the VOYAGER interplanetary mission are as  
follows: 
- investigate the structure of the solar wind magnetic fields and plasma in the
inner and outer heliosphere; 
- conduct long term study of heliospheric evolution during different phases of
the twenty-two year solar magnetic cycle and the eleven-year solar activity
cycle;
- study the long term solar modulation and determine the elemental and isotopic
abundances of galactic cosmic ray particles in the heliosphere;
- measure  radial gradients, spectra, and nuclear abundances of the anomalous
component of cosmic rays  from  acceleration at the solar wind termination
shock; 
- investigate local particle acceleration in the interplanetary medium from
solar flare shocks and corotating interaction regions; 
- study propagation of solar energetic particles in the heliosphere.
This directory contains hourly averages of parameters for the interplanetary
magnetic field, solar wind plasma and spacecraft trajectory coordinates
VOYAGER-1 data have been reprocessed to ensure a uniformity of content and
coordinate systems relative to data from other deep-space missions:
 - All spacecraft trajectory data were transformed to a Heliographic Inertial
(HGI) coordinate system.
- calculation of the RTN Cartesian components of interplanetary magnetic field
from the RTN spherical components: 
         BR=|B|*cos(THETA)*cos(PHI) 
         BT=|B|*cos(THETA)*sin(PHI) 
         BN=|B|*sin(THETA)          
where THETA - spherical RTN latitude, PHI- spherical RTN longtitude 
- calculation of RTN Spherical components of the solar wind velocity from RTN
cartesian components:
         V = (Vr^2 + Vt^2 + Vn^2)^0.5
         THETA=asin(Vn/V)
         PHI=atan(Vt/Vr)
where THETA - spherical RTN latitude, PHI- spherical RTN longtitude
- calculation of given thermal speed Vth into temperature T (Kelvin):
         T=60.5*Vth^2 (Vth in km/s)
- merging of trajectory coordinates, magnetic field data, and plasma data files
into a single annual file VY1_YR.DAT, where YR is the year
- Data gaps were filled with dummy numbers for the missing hours or entire days
to make all files of equal length.  The character \Ə\' is used to fill all
fields for missing data according to their format, e.g. \' 9999.9\' for a field
with the FORTRAN format F7.1. Note that format F7.1 below really means
(1X,F6.1),etc.a
Notes on Voyager 1 and 2 Magnetometer Data After 1989.
  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; 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 ..0.15 nT and ..0.05
nT, respectively. The use of roll calibrations lasting ..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 ..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 nT - 0.05 nT. further informaion look at
https://omniweb.gsfc.nasa.gov/coho/html/cw_data.html
The Heliographic Inertial (HGI) coordinates are Sun-centered and inertially
fixed with respect to an X-axis directed along the intersection line of the
ecliptic and solar equatorial planes.  The solar equator plane is inclined at
7.25 degrees from the ecliptic.  This direction was towards ecliptic longitude
of 74.36 degrees on 1 January 1900 at 1200 UT; because of precession of the
celestial equator, this longitude increases by 1.4 degrees/century. The Z axis
is directed perpendicular and northward from the solar equator, and the  Y-axis
completes the right-handed set. This system differs from the usual  heliographic
 coordinates  (e.g. Carrington longitudes) which are fixed in the frame of the
rotating Sun. 
The RTN system is fixed at a spacecraft (or the planet). The R axis is  directed
radially away from the Sun, the T axis is the cross product of the solar
rotation axis and the R axis, and the N axis is the cross product of R and T. 
At zero Heliographic Latitude when the spacecraft is in the solar equatorial
plane the N and solar rotation axes are parallel.
Hour averages of the interplanetary solar wind data from, and hourly
heliocentric coordinates of, Voyager1/2 and other interplanetary spacecraft may
be also be accessed and plotted on-line through the COHOWeb service 
http://cohoweb.gsfc.nasa.gov/
Acknowledgement: Use of these data in publications should be accompanied at
minimum by acknowledgements of the National Space Science Data Center and the
responsible Principal Investigator defined in the experiment documentation
provided here.  Citation of NSSDC's Coordinated Heliospheric Observations (COHO)
data base would also be appreciated, so that other potential users will be made
aware of this service. 
For questions about this data set, please contact: Dr. N. Papitashvili,
natalia.e.papitashvili@nasa.gov, GSFC-Code 672
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VOYAGER1_CRS_DAILY_FLUX (spase://NASA/NumericalData/Voyager1/CRS/Flux/EnergyFlux/HydrogenHelium/LevelH3/CDF/P1D)
Description
Please visit Voyager CRS website https://voyager.gsfc.nasa.gov
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VOYAGER1_HELIO1DAY_POSITION (spase://NASA/NumericalData/Voyager1/HelioWeb/Ephemeris/P1D)
Description
No TEXT global attribute value.
Dataset in CDAWeb
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VOYAGER1_PLS_COMPOSITION (spase://NASA/NumericalData/Voyager1/PLS/Jupiter/Composition/VIPER/PT96S)
Description
These data are from a re-analysis of the Voyager Plasma Spectrometer (PLS) data
at Jupiter by the PLS group at the Laboratory for Atmospheric and Space Physics
(LASP) at the University of Colorado. Density, temperature, and flow velocity
fits for total and individual ions were done using the Voyager Ion PLS
Experiment Response (VIPER) code and error analysis as described at
http://lasp.colorado.edu/home.mop/missions/voyager/viper/. Fits are determined
from processing of the ion currents from the A, B, C, and D cups of the
instrument.. As per the Fit Case variable, one of five different constraints
were used in the VIPER fits for each 96-sec time interval: (1) free variation of
all parameters (mainly for the cold ion torus); (2) constraint of the ion
abundances for the five major species (O+, O++, S+, S++, S+++) to standard
composition as determined from Delamere et al. (2005); (3) fixed ion composition
and flow speed; (4) cold blobs in the plasma sheet where resolved peaks can be
fit with allowance for some variance in composition; (5) interpolation between
composition of cold torus and standard abundances at 6 RJ from Delamere et al.
(2005). 
Reference: Delamere, P. A., Bagenal, F., and Steffl, A. (2005), Radial
Variations in the Io Plasma Torus During the Cassini Era, Journal of Geophysical
Research Space Physics, 110(A12), A12223, doi: 10.1029/2005JA011251.
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VOYAGER1_PLS_ELECTRONS_E1 (spase://NASA/NumericalData/Voyager1/PLS/Jupiter/Electron/CurrentSpectra/LowEnergy/PT96S)
Description
1: These electron current spectra in the jovian magnetosphere are from the
Plasma Spectrometer (PLS) instrument on Voyager 1 during March 1979 flyby of
Jupiter. The instrument has four Faraday Cups A - D, the electron data come only
from D. The data are specified in terms of current per cup in femto-amps (10^-15
A) versus channel number and energy (eV). 
2: This data set is for the PLS E1 mode covering electron energies of 10 - 140
eV in 16 energy channels. PLS samples only one mode of electron (E1, E2) or ion
(L, M) spectra in each time intervals, so the E1 data are not continuous but
consecutive with the other modes in time. 
3: Reference: Bridge et al. (1977). The Plasma Experiment on the the 1977
Voyager Mission, Space Science Reviews, 21, 259-287.
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VOYAGER1_PLS_ELECTRONS_E2 (spase://NASA/NumericalData/Voyager1/PLS/Jupiter/Electron/CurrentSpectra/HighEnergy/PT96S)
Description
These electron current spectra in the jovian magnetosphere are from the Plasma
Spectrometer (PLS) instrument on Voyager 1 during the March 1979 flyby of
Jupiter. The instrument has four Faraday Cups A - D, the electron data come only
from D. The data are specified in terms of current per cup in femto-amps (10^-15
A) versus channel number and energy (eV). This data set is for the PLS E1 mode
covering electron energies of 10 - 140 eV in 16 energy channels. PLS samples
only one mode of electron (E1, E2) or ion (L, M) spectra in each time intervals,
so the E1 data are not continuous but consecutive with the other modes in time. 
Reference: Bridge et al. (1977). The Plasma Experiment on the the 1977 Voyager
Mission, Space Science Reviews, 21, 259-287.
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VOYAGER1_PLS_HIRES_PLASMA_DATA (spase://NASA/NumericalData/Voyager1/PLS/HIRES/CDF/PT12S)
Description
The files in this directory contain the Voyager fine resolution plasma data. The
plasma parameters are obtained by finding the best fit of a convected isotropic
Maxwellian distribution to the data. One sigma errors are typically less than
0.5% in the speed and VR, less than 5% for the density and thermal speed, and
vary greatly for VT and VN. Sampling times range from 12 to 192 sec., with
sampling generally more frequent early in the mission.
The velocity components are given in the RTN coordinate system, where R is
radially outward, T is in a plane parallel to the solar equatorial plane and
positive in the direction of solar rotation, and N completes a right-handed
system.
(WARNING: V_t, and V_n parameters are often NOT reliable after 1989)
Please consult with us, or at least send preprints, when you use this data to
prevent grievous errors or misconceptions. (John Richardson, jdr@space.mit.edu)
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VOYAGER1_PLS_IONS_L (spase://NASA/NumericalData/Voyager1/PLS/Jupiter/Ion/CurrentSpectra/LowEnergyResolution/PT96S)
Description
These ion current spectra in the jovian magnetosphere are from the Plasma
Spectrometer (PLS) instrument on Voyager 1 during the March 1979 flyby of
Jupiter. The instrument has four Faraday Cups A - D, the electron data come only
from D. The data are specified in terms of current per cup in femto-amps (10^-15
A) versus channel number and energy (eV). This data set is for the PLS L-mode
covering H+ ion energies of 10 - 5950 eV at low energy resolution in 16
logarithmic energy channels. PLS samples only one mode of electron (E1, E2) or
ion (L, M) spectra in each time interval, so the L-mode data are not continuous
but consecutive with the other modes in time. 
Reference: Bridge et al. (1977). The Plasma Experiment on the the 1977 Voyager
Mission, Space Science Reviews, 21, 259-287.
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VOYAGER1_PLS_IONS_M (spase://NASA/NumericalData/Voyager1/PLS/Jupiter/Ion/CurrentSpectra/HighEnergyResolution/PT96S)
Description
These ion current spectra in the jovian magnetosphere are from the Plasma
Spectrometer (PLS) instrument on Voyager 1 during the March 1979 flyby of
Jupiter. The instrument has four Faraday Cups A - D, the electron data come only
from D. The data are specified in terms of current per cup in femto-amps (10^-15
A) versus channel number and energy (eV). 
This data set is for the PLS M-mode covering H+ ion energies of 10 - 5950 eV at
high energy resolution in 128 logarithmic energy channels. PLS samples only one
mode of electron (E1, E2) or ion (L, M) spectra in each time interval, so the
M-mode data are not continuous but consecutive with the other modes in time.
Reference: Bridge et al. (1977). The Plasma Experiment on the the 1977 Voyager
Mission, Space Science Reviews, 21, 259-287.
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VOYAGER2_10S_MAG (spase://NASA/NumericalData/Voyager2/MAG/CDF/PT9.6S)
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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VOYAGER2_2S_MAG (spase://NASA/NumericalData/Voyager2/MAG/CDF/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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VOYAGER2_48S_MAG (spase://NASA/NumericalData/Voyager2/MAG/CDF/PT48S)
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.
Support data calib_flag_on, calib_flag_MF and calib_flag_offset are added to
file version 2. Variable calib_flag_on consists of points where bit 4 or 5 in
variable magStatus equal 1. Variable calib_flag_MF represents observations where
magnetometer was in cailbration mode. Variable calib_flag_offset represent delay
between data points where magnetometer was in calibration mode and data points
where magStatus variable indicated calibration periods.Due to specific shape of
magnetometer data profile variable calibration_flag_MF may cover larger
intervals than calibration_flag_on.
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VOYAGER2_48S_MAG-VIM (spase://NASA/NumericalData/Voyager2/MAG/VIM/CDF/PT48S)
Description
The  main science objectives for the VOYAGER interplanetary mission are as  
follows: 
- investigate the structure of the solar wind magnetic fields and plasma in the
inner and outer heliosphere; 
- conduct long term study of heliospheric evolution during different phases of
the twenty-two year solar magnetic cycle and the eleven-year solar activity
cycle;
- study the long term solar modulation and determine the elemental and isotopic
abundances of galactic cosmic ray particles in the heliosphere;
- measure  radial gradients, spectra, and nuclear abundances of the anomalous
component of cosmic rays  from  acceleration at the solar wind termination
shock; 
- investigate local particle acceleration in the interplanetary medium from
solar flare shocks and corotating interaction regions; 
- study propagation of solar energetic particles in the heliosphere.
The average magnetic field strength produced by the spacecraft at the location
of the outboard magnetometer of the dual magnetometers system on V1 and V2 is
about 0.1 - 0.2 nT, comparable to the most probable magnetic field strength in
the inner heliosheath and significantly larger than the most probable magnetic
field strength in the distant supersonic solar wind. The spacecraft magnetic
field is a complex, time-dependent signal that must be removed from the measured
magnetic field signal in order to derive the ambient magnetic fields of the
solar wind and heliosheath. Corrections must also be made for spurious magnetic
signals and noise associated with the telemetry system, ground tracking systems,
and other factors. 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. We
estimate that for the V1 MAG data the 1-sigma the uncertainty the 48 sec
averages for each of the components of the magnetic field  BR, BT, and BN is
typically +/- 0.02 nT; the uncertainty in magnitude F1 is typically +/- 0.03 nT.
F1, BR, BT, and BN can differ from one another and they may vary with time, but
there is no practical way to determine these uncertainties more precisely at
present.
References
Daniel B. Berdichevsky, Voyager Mission, Detailed processing of weak magnetic
fields; I - Constraints to the uncertainties of the calibrated magnetic field
signal in the Voyager missions , 2009;
https://vgrmag.gsfc.nasa.gov/Berdichevsky-VOY_sensor_opu090518.pdf
Behannon, K.W., M.H. Acu..a, 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.
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VOYAGER2_COHO1HR_MERGED_MAG_PLASMA (spase://NASA/NumericalData/Voyager2/MAGandPLS/PT1H)
Description
The  main science objectives for the VOYAGER interplanetary mission are as  
follows: 
- investigate the structure of the solar wind magnetic fields and plasma in the
inner and outer heliosphere; 
- conduct long term study of heliospheric evolution during different phases of
the twenty-two year solar magnetic cycle and the eleven-year solar activity
cycle;
- study the long term solar modulation and determine the elemental and isotopic
abundances of galactic cosmic ray particles in the heliosphere;
- measure  radial gradients, spectra, and nuclear abundances of the anomalous
component of cosmic rays  from  acceleration at the solar wind termination
shock; 
- investigate local particle acceleration in the interplanetary medium from
solar flare shocks and corotating interaction regions; 
- study propagation of solar energetic particles in the heliosphere.
This directory contains hourly averages of parameters for the interplanetary
magnetic field, solar wind plasma and spacecraft trajectory coordinates
VOYAGER-1 data have been reprocessed to ensure a uniformity of content and
coordinate systems relative to data from other deep-space missions:
 - All spacecraft trajectory data were transformed to a Heliographic Inertial
(HGI) coordinate system.
- calculation of the RTN Cartesian components of interplanetary magnetic field
from the RTN spherical components: 
         BR=|B|*cos(THETA)*cos(PHI) 
         BT=|B|*cos(THETA)*sin(PHI) 
         BN=|B|*sin(THETA)          
where THETA - spherical RTN latitude, PHI- spherical RTN longtitude 
- calculation of RTN Spherical components of the solar wind velocity from RTN
cartesian components:
         V = (Vr^2 + Vt^2 + Vn^2)^0.5
         THETA=asin(Vn/V)
         PHI=atan(Vt/Vr)
where THETA - spherical RTN latitude, PHI- spherical RTN longtitude
- calculation of given thermal speed Vth into temperature T (Kelvin):
         T=60.5*Vth^2 (Vth in km/s)
- merging of trajectory coordinates, magnetic field data, and plasma data files
into a single annual file VY1_YR.DAT, where YR is the year
- Data gaps were filled with dummy numbers for the missing hours or entire days
to make all files of equal length.  The character \Ə\' is used to fill all
fields for missing data according to their format, e.g. \' 9999.9\' for a field
with the FORTRAN format F7.1. Note that format F7.1 below really means
(1X,F6.1),etc.a
Notes on Voyager 1 and 2 Magnetometer Data After 1989.
  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; 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 ..0.15 nT and ..0.05
nT, respectively. The use of roll calibrations lasting ..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 ..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 nT - 0.05 nT. further informaion look at
https://omniweb.gsfc.nasa.gov/coho/html/cw_data.html
The Heliographic Inertial (HGI) coordinates are Sun-centered and inertially
fixed with respect to an X-axis directed along the intersection line of the
ecliptic and solar equatorial planes.  The solar equator plane is inclined at
7.25 degrees from the ecliptic.  This direction was towards ecliptic longitude
of 74.36 degrees on 1 January 1900 at 1200 UT; because of precession of the
celestial equator, this longitude increases by 1.4 degrees/century. The Z axis
is directed perpendicular and northward from the solar equator, and the  Y-axis
completes the right-handed set. This system differs from the usual  heliographic
 coordinates  (e.g. Carrington longitudes) which are fixed in the frame of the
rotating Sun. 
The RTN system is fixed at a spacecraft (or the planet). The R axis is  directed
radially away from the Sun, the T axis is the cross product of the solar
rotation axis and the R axis, and the N axis is the cross product of R and T. 
At zero Heliographic Latitude when the spacecraft is in the solar equatorial
plane the N and solar rotation axes are parallel.
Hour averages of the interplanetary solar wind data from, and hourly
heliocentric coordinates of, Voyager1/2 and other interplanetary spacecraft may
be also be accessed and plotted on-line through the COHOWeb service 
http://cohoweb.gsfc.nasa.gov/
Acknowledgement: Use of these data in publications should be accompanied at
minimum by acknowledgements of the National Space Science Data Center and the
responsible Principal Investigator defined in the experiment documentation
provided here.  Citation of NSSDC's Coordinated Heliospheric Observations (COHO)
data base would also be appreciated, so that other potential users will be made
aware of this service. 
For questions about this data set, please contact: Dr. N. Papitashvili,
natalia.e.papitashvili@nasa.gov, GSFC-Code 672
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VOYAGER2_HELIO1DAY_POSITION (spase://NASA/NumericalData/Voyager2/HelioWeb/Ephemeris/P1D)
Description
No TEXT global attribute value.
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VOYAGER2_PLS_COMPOSITION (spase://NASA/NumericalData/Voyager2/PLS/Jupiter/Composition/VIPER/PT96S)
Description
These data are from a re-analysis of the Voyager Plasma Spectrometer (PLS) data
at Jupiter by the PLS group at the Laboratory for Atmospheric and Space Physics
(LASP) at the University of Colorado. Density, temperature, and flow velocity
fits for total and individual ions were done using the Voyager Ion PLS
Experiment Response (VIPER) code and error analysis as described at
http://lasp.colorado.edu/home.mop/missions/voyager/viper/. Fits are determined
from processing of the ion currents from the A, B, C, and D cups of the
instrument.. As per the Fit Case variable, one of five different constraints
were used in the VIPER fits for each 96-sec time interval: (1) free variation of
all parameters (mainly for the cold ion torus); (2) constraint of the ion
abundances for the five major species (O+, O++, S+, S++, S+++) to standard
composition as determined from Delamere et al. (2005); (3) fixed ion composition
and flow speed; (4) cold blobs in the plasma sheet where resolved peaks can be
fit with allowance for some variance in composition; (5) interpolation between
composition of cold torus and standard abundances at 6 RJ from Delamere et al.
(2005). 
Reference: Delamere, P. A., Bagenal, F., and Steffl, A. (2005), Radial
Variations in the Io Plasma Torus During the Cassini Era, Journal of Geophysical
Research Space Physics, 110(A12), A12223, doi: 10.1029/2005JA011251.
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VOYAGER2_PLS_ELECTRONS_E1 (spase://NASA/NumericalData/Voyager2/PLS/Jupiter/Electron/CurrentSpectra/LowEnergy/PT96S)
Description
These electron current spectra in the jovian magnetosphere are from the Plasma
Spectrometer (PLS) instrument on Voyager 1 during the March 1979 flyby of
Jupiter. The instrument has four Faraday Cups A - D, the electron data come only
from D. The data are specified in terms of current per cup in femto-amps (10^-15
A) versus channel number and energy (eV). This data set is for the PLS E1 mode
covering electron energies of 10 - 140 eV in 16 energy channels. PLS samples
only one mode of electron (E1, E2) or ion (L, M) spectra in each time intervals,
so the E1 data are not continuous but consecutive with the other modes in time. 
Reference: Bridge et al. (1977). The Plasma Experiment on the the 1977 Voyager
Mission, Space Science Reviews, 21, 259-287.
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VOYAGER2_PLS_ELECTRONS_E2 (spase://NASA/NumericalData/Voyager2/PLS/Jupiter/Electron/CurrentSpectra/HighEnergy/PT96S)
Description
These electron current spectra in the jovian magnetosphere are from the Plasma
Spectrometer (PLS) instrument on Voyager 1 during the March 1979 flyby of
Jupiter. The instrument has four Faraday Cups A - D, the electron data come only
from D. The data are specified in terms of current per cup in femto-amps (10^-15
A) versus channel number and energy (eV). This data set is for the PLS E1 mode
covering electron energies of 10 - 140 eV in 16 energy channels. PLS samples
only one mode of electron (E1, E2) or ion (L, M) spectra in each time intervals,
so the E1 data are not continuous but consecutive with the other modes in time. 
Reference: Bridge et al. (1977). The Plasma Experiment on the the 1977 Voyager
Mission, Space Science Reviews, 21, 259-287.
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VOYAGER2_PLS_HIRES_PLASMA_DATA (spase://NASA/NumericalData/Voyager2/PLS/HIRES/CDF/PT12S)
Description
The files in this directory contain the Voyager fine resolution plasma data. The
plasma parameters are obtained by finding the best fit of a convected isotropic
Maxwellian distribution to the data. One sigma errors are typically less than
0.5% in the speed and VR, less than 5% for the density and thermal speed, and
vary greatly for VT and VN. Sampling times range from 12 to 192 sec., with
sampling generally more frequent early in the mission.
The velocity components are given in the RTN coordinate system, where R is
radially outward, T is in a plane parallel to the solar equatorial plane and
positive in the direction of solar rotation, and N completes a right-handed
system.
(WARNING: V_t, and V_n parameters are often NOT reliable after 1989)
Please consult with us, or at least send preprints, when you use this data to
prevent grievous errors or misconceptions. (John Richardson, jdr@space.mit.edu)
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VOYAGER2_PLS_HIRES_PLASMA_DATA_HSH
Description
The files in this directory contain the Voyager fine resolution plasma data. The
plasma parameters are obtained by finding the best fit of a convected isotropic
Maxwellian distribution to the data. One sigma errors are typically less than
0.5% in the speed and VR, less than 5% for the density and thermal speed, and
vary greatly for VT and VN. Sampling times range from 12 to 192 sec., with
sampling generally more frequent early in the mission.
The velocity components are given in the RTN coordinate system, where R is
radially outward, T is in a plane parallel to the solar equatorial plane and
positive in the direction of solar rotation, and N completes a right-handed
system.
(WARNING: V_t, and V_n parameters are often NOT reliable after 1989)
Please consult with us, or at least send preprints, when you use this data to
prevent grievous errors or misconceptions. (John Richardson, jdr@space.mit.edu)
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VOYAGER2_PLS_IONS_L (spase://NASA/NumericalData/Voyager2/PLS/Jupiter/Ion/CurrentSpectra/LowEnergyResolution/PT96S)
Description
These ion current spectra in the jovian magnetosphere are from the Plasma
Spectrometer (PLS) instrument on Voyager 2 during the July 1979 flyby of
Jupiter. The instrument has four Faraday Cups A - D, the electron data come only
from D. The data are specified in terms of current per cup in femto-amps (10^-15
A) versus channel number and energy (eV). This data set is for the PLS L-mode
covering H+ ion energies of 10 - 5950 eV at low energy resolution in 16
logarithmic energy channels. PLS samples only one mode of electron (E1, E2) or
ion (L, M) spectra in each time interval, so the L-mode data are not continuous
but consecutive with the other modes in time. 
Reference: Bridge et al. (1977). The Plasma Experiment on the the 1977 Voyager
Mission, Space Science Reviews, 21, 259-287.
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VOYAGER2_PLS_IONS_M (spase://NASA/NumericalData/Voyager2/PLS/Jupiter/Ion/CurrentSpectra/HighEnergyResolution/PT96S)
Description
These ion current spectra in the jovian magnetosphere are from the Plasma
Spectrometer (PLS) instrument on Voyager 2 during the July 1979 flyby of
Jupiter. The instrument has four Faraday Cups A - D, the electron data come only
from D. The data are specified in terms of current per cup in femto-amps (10^-15
A) versus channel number and energy (eV). 
This data set is for the PLS M-mode covering H+ ion energies of 10 - 5950 eV at
high energy resolution in 128 logarithmic energy channels. PLS samples only one
mode of electron (E1, E2) or ion (L, M) spectra in each time interval, so the
M-mode data are not continuous but consecutive with the other modes in time.
Reference: Bridge et al. (1977). The Plasma Experiment on the the 1977 Voyager
Mission, Space Science Reviews, 21, 259-287.
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