The IVM consists of two planar thermal ion sensors, a retarding potential analyzer (RPA) and an ion drift meter (IDM).

Time at the midpoint of the IVM measurements.

Binary Coded Integer from Technical Note ICN-TN-027.
1: Earth Day View
2: Earth Night View
4: Calibration Target View
8: Off-target View
16: Sun Proximity View
32: Moon Proximity View
64: North Magnetic Footpoint View
128: South Magnetic Footpoint View
256: Science Data Collection View
512: Calibration Data Collection View
1024: RAM Proximity View.

Binary Coded Integer from Technical Note ICN-TN-027.
1: Earth Day View
2: Earth Night View
4: Calibration Target View
8: Off-target View
16: Sun Proximity View
32: Moon Proximity View
64: North Magnetic Footpoint View
128: South Magnetic Footpoint View
256: Science Data Collection View
512: Calibration Data Collection View
1024: RAM Proximity View.

Geodetic Altitude of Spacecraft in WGS84.

Modified APEX height for S/C position.

Binary Coded Integer from Technical Note ICN-TN-027.
1: Earth Day View
2: Earth Night View
4: Calibration Target View
8: Off-target View
16: Sun Proximity View
32: Moon Proximity View
64: North Magnetic Footpoint View
128: South Magnetic Footpoint View
256: Science Data Collection View
512: Calibration Data Collection View
1024: RAM Proximity View.

Binary Coded Integer from Technical Note ICN-TN-027.
1: Earth Day View
2: Earth Night View
4: Calibration Target View
8: Off-target View
16: Sun Proximity View
32: Moon Proximity View
64: North Magnetic Footpoint View
128: South Magnetic Footpoint View
256: Science Data Collection View
512: Calibration Data Collection View
1024: RAM Proximity View
2048-32768: SPARE

Drift meter quality flag. 0 - Good data. 1 - Data may have artifacts due to s/c operations. 2 - Data temporarily removed for photoemission. 3 - Not enough O+ to measure arrival angle.

Velocity along local magnetic meridional direction, perpendicular to geomagnetic field and within local magnetic meridional plane, field-line mapped to apex/magnetic equator. The meridional vector is purely vertical at the magnetic equator, positive up. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the magnetic equator. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d).

Velocity along local magnetic zonal direction, perpendicular to geomagnetic field and the local magnetic meridional plane, field-line mapped to apex/magnetic equator. The zonal vector is purely horizontal when mapped to the magnetic equator, positive is generally eastward. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the magnetic equator. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d).

Altitude location of the magnetic footpoint in Northern Hemisphere at 150 km. These data were interpolated using tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times. These values should all be 150 km.

Altitude location of the magnetic footpoint in Northern Hemisphere at 150 km. These data were interpolated using tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times. These values should all be 150 km.

At the northern footpoint this is the x-component of the unit vector for field aligned ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the Southern footpoint this is the y-component of the unit vector for field aligned ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the northern footpoint this is the y-component of the unit vector for field aligned ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the Southern footpoint this is the y-component of the unit vector for field aligned ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the northern footpoint this is the z-component of the unit vector for field aligned ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the Southern footpoint this is the z-component of the unit vector for field aligned ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

Latitude location of the magnetic footpoint in Northern Hemisphere at 150 km. These data were interpolated using tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times.

Latitude location of the magnetic footpoint in Southern Hemisphere at 150 km. These data were interpolated using tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times.

Longitude location of the magnetic footpoint in Northern Hemisphere at 150 km. These data were interpolated using tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times.

Longitude location of the magnetic footpoint in Southern Hemisphere at 150 km. These data were interpolated using tricubic algorithm from IGRF and ephemeris data then linearly interploted to IVM times.

Calculated value of quesi dipole latitude of northern footpoint from IGRF.

Calculated value of quesi dipole latitude of southern footpoint from IGRF.

Calculated value of quesi dipole longitude of northern footpoint from IGRF.

Calculated value of quesi dipole longitude of southern footpoint from IGRF.

Velocity along local magnetic meridional direction, perpendicular to geomagnetic field and within local magnetic meridional plane, field-line mapped to northern footpoint. The meridional vector is purely vertical at the magnetic equator, positive up. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the magnetic footpoint. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d).

Velocity along local magnetic meridional direction, perpendicular to geomagnetic field and within local magnetic meridional plane, field-line mapped to southern footpoint. The meridional vector is purely vertical at the magnetic equator, positive up. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the magnetic footpoint. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d).

At the northern footpoint this is the x-component of the unit vector for meridional ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the Southern footpoint this is the y-component of the unit vector for meridional ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the northern footpoint this is the y-component of the unit vector for meridional ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the Southern footpoint this is the y-component of the unit vector for meridional ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the northern footpoint this is the z-component of the unit vector for meridional ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the Southern footpoint this is the z-component of the unit vector for meridional ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

Velocity along local magnetic zonal direction, perpendicular to geomagnetic field and the local magnetic meridional plane, field-line mapped to northern footpoint. The zonal vector is purely horizontal when mapped to the magnetic equator, positive is generally eastward. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the northern footpoint. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d).

Velocity along local magnetic zonal direction, perpendicular to geomagnetic field and the local magnetic meridional plane, field-line mapped to southern footpoint. The zonal vector is purely horizontal when mapped to the magnetic equator, positive is generally eastward. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame. Field-line mapping and the assumption of equi-potential field lines is used to translate the locally measured ion motion to the southern footpoint. The mapping is used to determine the change in magnetic field line distance, which, under assumption of equipotential field lines, in turn alters the electric field at that location (E=V/d).

At the northern footpoint this is the x-component of the unit vector for zonal ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the Southern footpoint this is the x-component of the unit vector for zonal ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the northern footpoint this is the y-component of the unit vector for zonal ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the Southern footpoint this is the y-component of the unit vector for zonal ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the northern footpoint this is the z-component of the unit vector for zonal ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

At the Southern footpoint this is the z-component of the unit vector for zonal ion drifts expressed in the Earth-Centered, Earth-Fixed frame.

Determined via a non-linear least squares fit of retarding potential analyzers currents.

Determined via a non-linear least squares fit of retarding potential analyzers currents.

Milliseconds since 1980-01-06 00:00:00 TAI (coincident with UTC) at middle of reading.

Time is generated from the time-code at byte 1015 of the IVM packet minus the time sync at byte 1019 of the IVM packet. This is the GPS time at the start of the integration period. The integration period is assumed to be 4 seconds so the center time is 2 seconds after that. The formula is (time-code * 1000ms) + 2000ms - (16 * time sync / 1000) in GPS milliseconds then converted to UTC time. See the UTD 206-024 Rev A document.

Time may be delayed by up to 10 ms due to FSW polling delay.

Maximum time is ~2150 UTC and minimum time is ~1970 UTC.

Incident plasma will have some potential relative to the IVM aperture plane. The aperture plane voltage matches that of a conductor allowed to float electrically with respect to the spacecraft. The flux of ions (driven by s/c motion) must be balanced by the flux of electrons (driven by electron temperature). The value of the aperture plane potential evolves naturally to limit the collection of electrons such the net flux is zero.

Ion density uses measured currents and co-rotating atmosphere to determine density.

Temperature is obtained by assuming single temperature value for all plasma.

Ion velocity relative to co-rotation along geomagnetic field lines. Positive along the main field vector. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame to express the observed vector along a geomagnetic basis.

Ion velocity along local magnetic meridional direction, perpendicular to geomagnetic field and within local magnetic meridional plane. The local meridional vector maps to vertical at the magnetic equator, positive is up. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame to express the observed vector along a geomagnetic basis.

Velocity is relative to co-rotation. Positive-x is normal to IVM aperture plane and in the direction of satellite motion. Velocity obtained through fitting of retarding potential analyzers currents to measure the along track ion velocity. Signals produced by the motion of the spacecraft and the rotation of the Earth are removed to produce this result.

Velocity is relative to co-rotation. Positive-y points generally southward. Velocity obtained through conversion of arrival angles measured by the DM into a cross track velocity using trigonometry. Signals produced by the motion of the spacecraft and the rotation of the Earth are removed to produce this result.

Velocity is relative to co-rotation. Positive-z is directed towards nadir (Earth). Velocity obtained through conversion of arrival angles measured by the DM into a cross track velocity using trigonometry. Signals produced by the motion of the spacecraft and the rotation of the Earth are removed to produce this result.

Ion velocity relative to co-rotation along the magnetic zonal direction, normal to local magnetic meridional plane and the geomagnetic field (positive east). The local zonal vector maps to purely horizontal at the magnetic equator. Velocity obtained using ion velocities relative to co-rotation in the instrument frame along with the corresponding unit vectors expressed in the instrument frame to express the observed vector along a geomagnetic basis.

WGS84 Latitude of spacecraft position (geodetic).

Geodetic Longitude of Spacecraft in WGS84.

If the MTB are active during any part of the measurement, it is recorded as active for whole measurement. Decoded from s/c housekeeping file: /disks/icondata/Temporary/ICON.SDC.Pipeline.IVM.Ancillary.2020-03-13T161524.20CD292B-2A3B-4142-86C9-5D73B55AFDCE/Input/ICON_L0_Spacecraft_Housekeeping-MTB_2019-11-01_v01r010.CSV If the MTB are active during any part of the measurement, it is recorded as active for whole measurement. Decoded from s/c housekeeping file.

Quasi-dipole magnetic latitude for spacecraft position.

Magnetic Local Time at spacecraft.

Quasi-dipole magnetic longitude for spacecraft position.

Earth Centered Inertial Earth Corotation Velocity Component of Earth's corotation velocity in the IVM instrament axes. [(X,Y,Z),Epoch].

Earth Centered Inertial Earth Corotation Velocity Component of Earth's corotation velocity in the IVM instrament axes. [(X,Y,Z),Epoch].

Earth Centered Inertial Earth Corotation Velocity Component of Earth's corotation velocity in the IVM instrament axes. [(X,Y,Z),Epoch].

Magnetic field from IGRF at v position, expressed in the Earth-Centered, Earth-Fixed frame. x - component

Magnetic field from IGRF at spacecraft position, expressed in the Earth-Centered, Earth-Fixed frame. y - component

Magnetic field from IGRF at spacecraft position, expressed in the Earth-Centered, Earth-Fixed frame. z - component

Velocity of spacecraft in Earth Centered Inertial, J2000, cooridinates. Array is set up as [(X,Y,Z),Epoch]

Velocity of spacecraft in Earth Centered Inertial, J2000, cooridinates. Array is set up as [(X,Y,Z),Epoch]

Velocity of spacecraft in Earth Centered Inertial, J2000, cooridinates. Array is set up as [(X,Y,Z),Epoch]

Orbit Number

Status flag for retarding potential analyzers. 0 - All retarding potential analyzers parameters are good. Ion temperatures correspond to both O+ and H+. 1 - Ram Ion Velocities are not good. Other parameters good. Plasma is presumed to be co-rotating when fitting retarding potential analyzers curves that have an insufficient quantity of O+. Ion temperatures correspond to H+ only. 2 - Geophysical outputs may be impacted by spacecraft operations..

This is the total ion velocity along direction into the retarding potential analyzers, including spacecraft motion.

This is the total ion velocity along direction into the retarding potential analyzers, including spacecraft motion.

This is the total ion velocity along direction into the retarding potential analyzers, including spacecraft motion.

Slew Status.

Local Solar Time at the spacecraft.

Solar Zenith Angle of spacecraft.

Standarized for several missions, not all codes are relevant. Binary Coded Integer from Technical Note ICN-TN-027.
1: Earth Shadow
2: Lunar Shadow
4: Atmospheric Absorption Zone
8: South Atlantic Anomaly
16: Northern Auroral Zone
32: Southern Auroral Zone
64: Periapsis Passage
128: Inner and Outer Radiation Belts
256: Deep Plasma Sphere
512: Foreshock Solar Wind
1024: Solar Wind Beam
2048: High Magnetic Field
4096: Average Plasma Sheet
8192: Bowshock Crossing
16384: Magnetopause Crossing
32768: Ground Based Observatories
65536: 2-Day Conjunctions
131072: 4-Day Conjunctions
262144: Time Based Conjunctions
524288: Radial Distance Region 1
1048576: Orbit Outbound
2097152: Orbit Inbound
4194304: Lunar Wake
8388608: Magnetotail
16777216: Magnetosheath
33554432: Science
67108864: Low Magnetic Latitude
134217728: Conjugate Observation.

Spacecraft Sun/Shadow Status Code.

Milliseconds since 1970-01-01 00:00:00 UTC at start of reading.

Time is generated from the time-code at byte 1015 of the IVM packet minus the time sync at byte 1019 of the IVM packet. This is the GPS time at the start of the integration period. The integration period is assumed to be 4 seconds so the center time is 2 seconds after that. The formula is (time-code * 1000ms) + 2000ms - (16 * time sync / 1000) in GPS milliseconds then converted to UTC time. See the UTD 206-024 Rev A document.

Time may be delayed by up to 10 ms due to FSW polling delay.

Maximum time is ~2150 UTC and minimum time is ~1970 UTC.

Milliseconds since 1970-01-01 00:00:00 UTC at end of reading.

Time is generated from the time-code at byte 1015 of the IVM packet minus the time sync at byte 1019 of the IVM packet. This is the GPS time at the start of the integration period. The integration period is assumed to be 4 seconds so the center time is 2 seconds after that. The formula is (time-code * 1000ms) + 2000ms - (16 * time sync / 1000) in GPS milliseconds then converted to UTC time. See the UTD 206-024 Rev A document.

Time may be delayed by up to 10 ms due to FSW polling delay.

Maximum time is ~2150 UTC and minimum time is ~1970 UTC.

ISO 9601 formatted UTC timestamp (at middle of reading).

Time is generated from the time-code at byte 1015 of the IVM packet minus the time sync at byte 1019 of the IVM packet. This is the GPS time at the start of the integration period. The integration period is assumed to be 4 seconds so the center time is 2 seconds after that. The formula is (time-code * 1000ms) + 2000ms - (16 * time sync / 1000) in GPS milliseconds then converted to UTC time. See the UTD 206-024 Rev A document.

Time may be delayed by up to 10 ms due to FSW polling delay.

Maximum time is ~2150 UTC and minimum time is ~1970 UTC.

Positive along the field, generally northward. Unit vector is along the geomagnetic field. The unit vector is expressed in the IVM coordinate system, x - along RAM, z - towards nadir, y - completes the system, generally southward. Calculated using the corresponding unit vector in Earth-Centered, Earth-Fixed and the orientation of the IVM also expressed in Earth-Centered, Earth-Fixed (sc_hat_).

Positive along the field, generally northward. Unit vector is along the geomagnetic field. The unit vector is expressed in the IVM coordinate system, x - along RAM, z - towards nadir, y - completes the system, generally southward. Calculated using the corresponding unit vector in Earth-Centered, Earth-Fixed and the orientation of the IVM also expressed in Earth-Centered, Earth-Fixed (sc_hat_).

Positive along the field, generally northward. Unit vector is along the geomagnetic field. The unit vector is expressed in the IVM coordinate system, x - along RAM, z - towards nadir, y - completes the system, generally southward. Calculated using the corresponding unit vector in Earth-Centered, Earth-Fixed and the orientation of the IVM also expressed in Earth-Centered, Earth-Fixed (sc_hat_).

Positive is aligned with vertical at geomagnetic equator. Unit vector is perpendicular to the geomagnetic field and in the plane of the meridian.The unit vector is expressed in the IVM coordinate system, x - along RAM, z - towards nadir, y - completes the system, generally southward. Calculated using the corresponding unit vector in Earth-Centered, Earth-Fixed and the orientation of the IVM also expressed in Earth-Centered, Earth-Fixed (sc_hat_).

Positive is aligned with vertical at geomagnetic equator. Unit vector is perpendicular to the geomagnetic field and in the plane of the meridian.The unit vector is expressed in the IVM coordinate system, x - along RAM, z - towards nadir, y - completes the system, generally southward. Calculated using the corresponding unit vector in Earth-Centered, Earth-Fixed and the orientation of the IVM also expressed in Earth-Centered, Earth-Fixed (sc_hat_).

Positive is aligned with vertical at geomagnetic equator. Unit vector is perpendicular to the geomagnetic field and in the plane of the meridian.The unit vector is expressed in the IVM coordinate system, x - along RAM, z - towards nadir, y - completes the system, generally southward. Calculated using the corresponding unit vector in Earth-Centered, Earth-Fixed and the orientation of the IVM also expressed in Earth-Centered, Earth-Fixed (sc_hat_).

Positive towards the east. Zonal vector is normal to magnetic meridian plane. The unit vector is expressed in the IVM coordinate system, x - along RAM, z - towards nadir, y - completes the system, generally southward. Calculated using the corresponding unit vector in Earth-Centered, Earth-Fixed and the orientation of the IVM also expressed in Earth-Centered, Earth-Fixed (sc_hat_).

Positive towards the east. Zonal vector is normal to magnetic meridian plane. The unit vector is expressed in the IVM coordinate system, x - along RAM, z - towards nadir, y - completes the system, generally southward. Calculated using the corresponding unit vector in Earth-Centered, Earth-Fixed and the orientation of the IVM also expressed in Earth-Centered, Earth-Fixed (sc_hat_).

Positive towards the east. Zonal vector is normal to magnetic meridian plane. The unit vector is expressed in the IVM coordinate system, x - along RAM, z - towards nadir, y - completes the system, generally southward. Calculated using the corresponding unit vector in Earth-Centered, Earth-Fixed and the orientation of the IVM also expressed in Earth-Centered, Earth-Fixed (sc_hat_).