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DE 1 8-sec Position Data

ResourceID
spase://NASA/NumericalData/DE1/Ephemeris/PT8S

Description

Two Dynamics Explorer (DE) spacecraft were launched August 3, 1981, and placed into coplanar polar orbits with DE-1 in a highly elliptical orbit and DE-2 in a lower more circular orbit. The primary objective of the DE program was to investigate magnetosphere-ionosphere-atmosphere coupling processes. The DE mission provided a wealth of new information on a wide variety of magnetospheric plasma wave phenomena including auroral kilometric radiation, auroral hiss, Z mode radiation, narrow-band electromagnetic emissions associated with equatorial upper hybrid waves, whistler mode emissions, wave-particle interactions stimulated by ground VLF transmitters, equatorial ion cyclotron emissions, ion Bernstein mode emissions, and electric field turbulence along the auroral field lines. These files contain 8 second resolution emphemeris and spacecraft attitude parameters that coincide with DE-1 telemetry frames containing PWI lowrate data. These parameters are not to be taken as an authoritative set, but are convenient when working with PWI science data products. Most of these data are provided in the Geocentric Equatorial Inertial (GEI) TOD reference frame. The Z axis of the GEI frame is parallel to Earth's spin axis; the X axis points towards the First Point of Aries with the Y axis aligned so as to generate a right-handed coordinate system.

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Details

Version:2.2.9

NumericalData

ResourceID
spase://NASA/NumericalData/DE1/Ephemeris/PT8S
ResourceHeader
ResourceName
DE 1 8-sec Position Data
AlternateName
Dynamics Explorer 1 8 Second Orbit and Attitude Data
AlternateName
DE-A 8 Second Orbit and Attitude Data
ReleaseDate
2020-07-07 21:14:31Z
Description

Two Dynamics Explorer (DE) spacecraft were launched August 3, 1981, and placed into coplanar polar orbits with DE-1 in a highly elliptical orbit and DE-2 in a lower more circular orbit. The primary objective of the DE program was to investigate magnetosphere-ionosphere-atmosphere coupling processes. The DE mission provided a wealth of new information on a wide variety of magnetospheric plasma wave phenomena including auroral kilometric radiation, auroral hiss, Z mode radiation, narrow-band electromagnetic emissions associated with equatorial upper hybrid waves, whistler mode emissions, wave-particle interactions stimulated by ground VLF transmitters, equatorial ion cyclotron emissions, ion Bernstein mode emissions, and electric field turbulence along the auroral field lines. These files contain 8 second resolution emphemeris and spacecraft attitude parameters that coincide with DE-1 telemetry frames containing PWI lowrate data. These parameters are not to be taken as an authoritative set, but are convenient when working with PWI science data products. Most of these data are provided in the Geocentric Equatorial Inertial (GEI) TOD reference frame. The Z axis of the GEI frame is parallel to Earth's spin axis; the X axis points towards the First Point of Aries with the Y axis aligned so as to generate a right-handed coordinate system.

Acknowledgement
Users of the DE-1 PWI data are encouraged to acknowledge NASA CDAWeb and The University of Iowa as the source of the data in any publication.
Contacts
RolePerson
1.PrincipalInvestigatorspase://SMWG/Person/Donald.A.Gurnett
2.MetadataContactspase://SMWG/Person/Jolene.S.Pickett
3.MetadataContactspase://SMWG/Person/Larry.J.Granroth
4.MetadataContactspase://SMWG/Person/Chris.W.Piker
InformationURL
Name
The University of Iowa DE-1 PWI Page
URL
Description
Language
en
PriorIDs
spase://VWO/NumericalData/DynamicsExplorer1/Ephemeris/PT8S
spase://VSPO/NumericalData/DynamicsExplorer1/Ephemeris/PT8S
spase://VSPO/NumericalData/DE1/Ephemeris/PT8S
AccessInformation
RepositoryID
Availability
Online
AccessRights
Open
AccessURL
Name
FTP access to files at SPDF
URL
Description

Direct link to CDF format data via FTP from the SPDF.

AccessURL
Name
HTTP access to files at SPDF
URL
Description

Direct link to CDF format data via HTTP from the SPDF.

AccessURL
Name
CDAWeb
URL
ProductKey
DE1_PWI_OR-AT
Description

Access to ASCII, CDF, and plots via NASA/GSFC CDAWeb.

Format
CDF
Encoding
None
Acknowledgement
Users of the DE-1 PWI data are encouraged to acknowledge NASA CDAWeb and The University of Iowa as the source of the data in any publication.
ProcessingLevel
Calibrated
InstrumentIDs
MeasurementType
Ephemeris
TemporalDescription
TimeSpan
StartDate
1981-09-16 05:21:48
StopDate
1984-06-28 20:35:55
Cadence
PT8S
Parameter #1
Name
Epoch
ParameterKey
Epoch
Description

NSSDC standard reference time associated with the start of a PWI SFR sweep

Units
ms
Support
SupportQuantity
Temporal
Parameter #2
Name
GEI Velocity
ParameterKey
GEI_velocity
Description

GEI (Geocentric Equatorial Inertial) Satellite Velocity Vector (km/sec). The order of the vector components is v(x), v(y), v(z).

Units
km/sec
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
GEI
Support
SupportQuantity
Velocity
Parameter #3
Name
Altitude
ParameterKey
Altitude
Description

Altitude above a spheroid Earth, not above the geoid.

Units
km
Support
SupportQuantity
Positional
Parameter #4
Name
Geographic Latitude
ParameterKey
GLAT
Description

Geographic latitude of subsatellite point in degrees

Units
degrees
CoordinateSystem
CoordinateRepresentation
Spherical
CoordinateSystemName
GEO
ValidMin
-90.0
ValidMax
90.0
Support
SupportQuantity
Positional
Parameter #5
Name
Geographic Longitude
ParameterKey
GLON
Description

Geographic longitude of the satellite in degrees

Units
degrees
CoordinateSystem
CoordinateRepresentation
Spherical
CoordinateSystemName
GEO
ValidMin
-180.0
ValidMax
180.0
Support
SupportQuantity
Positional
Parameter #6
Name
MLT
ParameterKey
MLT
Description

Magnetic Local Time. MLT was defined via the conventional Solar Magnetic frame.

Units
hours
ValidMin
0.0
ValidMax
24.0
Support
SupportQuantity
Positional
Parameter #7
Name
L Shell
ParameterKey
L_Shell
Description

McIlwain's shell parameter (L)

Units
Re
Support
SupportQuantity
Positional
Parameter #8
Name
Invariant Latitude
ParameterKey
ILAT
Description

Current spacecraft field line footprint's geomagnetic latitude.

Units
degrees
ValidMin
-90.0
ValidMax
90.0
Support
SupportQuantity
Positional
Parameter #9
Name
B Magnitude
ParameterKey
B_Magnitude
Description

Magnetic field strength. Any discrepancy between these data and those provided by the magnetometer instrument's own files should be resolved in favor of the latter. See 'Magnetic Field Observations on DE-A and -B', W. H. Farthing, et al., Space Science Instrumentation 5 (1981) for more information.

Units
nT
Field
FieldQuantity
Magnetic
Parameter #10
Name
B Vector (GEI)
ParameterKey
GEI_B_vec
Description

GEI (Geocentric Equatorial Inertial) Magnetic Vector in nanoTesla. The order of the vector components is B(x), B(y), B(z). Any discrepancy between these data and those provided by the magnetometer instrument's own files should be resolved in favor of the latter. See 'Magnetic Field Observations on DE-A and -B', W. H. Farthing, et al., Space Science Instrumentation 5 (1981) for more information.

Units
nT
Field
FieldQuantity
Magnetic
Parameter #11
Name
Orbit Number
ParameterKey
Orbit_Number
Description

The orbit number from PWI archive files.

Support
SupportQuantity
Other
Parameter #12
Name
GEI Rotation
ParameterKey
GEI_rotation
Description

3-by-3 rotation matrix for the transformation from spacecraft coordinates to the GEI frame. The order of the elements is [1,1] = X(x), [1,2] = X(y), [1,3] = X(z), [2,1] = Y(x), [2,2] = Y(y), [2,3] = Y(z), [3,1] = Z(x), [3,2] = Z(y), and [3,3] = Z(z)

Support
SupportQuantity
Positional
Parameter #13
Name
GEI Position
ParameterKey
GEI_Position
Description

Spacecraft position in GEI coordinates, the order of the coordinates is X, Y, Z.

CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
GEI
Support
SupportQuantity
Positional
Parameter #14
Name
GEI Relative Velocity
ParameterKey
GEI_rel_vel
Description

GEI (Geocentric Equatorial Inertial) Satellite Velocity Vector (km/sec) relative to a rotating atmosphere.

Units
km/sec
CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
GEI
Support
SupportQuantity
Velocity
Parameter #15
Name
GEI Sun Position
ParameterKey
GEI_sun_pos
Description

GEI (Geocentric Equatorial Inertial) unit vector toward the sun. The order of the components is X, Y, Z.

CoordinateSystem
CoordinateRepresentation
Cartesian
CoordinateSystemName
GEI
Support
SupportQuantity
Positional
Parameter #16
Name
Spin Phase Angle
ParameterKey
Spin_Angle
Description

Angle between the Velocity Vector and the Spacecraft X-axis

Units
Degrees
ValidMin
-180.0
ValidMax
180.0
Support
SupportQuantity
Positional
Parameter #17
Name
SunFlag
ParameterKey
Sunlight
Description

Sunlight/Darkness flag, 0 = Darkness, 1 = Sunlight

Support
SupportQuantity
Other
Parameter #18
Name
Re
ParameterKey
Re
Description

Geocentric radial distance in Earth Radii. Here 1 Re = 6378.2 km

Units
Re
Support
SupportQuantity
Positional
Parameter #19
Name
Magnetic Latitude
ParameterKey
MLAT
Description

Magnetic latitude in degrees

Units
Degrees
ValidMin
-90.0
ValidMax
90.0
Support
SupportQuantity
Positional