GOES 12 magnetic field data at 0.512 s time resolution. The vector magnetic field is given in the spacecraft Earth-referenced coordinate system: Hp, He, Hn, and Ht, where Hp is perpendicular to the satellite orbital plane, or parallel to spin axis of the Earth in the case of a 0° inclination orbit, He is perpendicular to Hp and directed earthward, Hn is perpendicular to both Hp and He and directed eastward, and Ht is the total field.
This data product also provides GOES 12 satellite positions and velocities derived from SSCWEB GEI ephemeris, interpolated to 1 min time resolution.
The magnetometer data are downlinked from the spacecraft in real-time to the NOAA Space Weather Prediction Center (SWPC) in Boulder, Colorado. The data from the raw Command and Data Acquisition (CDA) telemetry stream are processed by pre-processors at SWPC and from there 1 min averages are distributed to SWPC Space Weather Operations, as well a archived at the NOAA National Geophysical Data Center (NGDC) and the NASA Coordinated Data Analysis Web (http://cdaweb.gsfc.nasa.gov/). The raw high resolution data are corrected and processed at the NOAA SWPC, and later archived at NGDC.
The major issue for processing the high resolution data is correction for the magnetic signature of spacecraft torquer currents as briefly discussed in the magnetometer instrument descriptions. In normal operation, the magnetometer samples its three axes every 0.512 s, synchronized with the telemetry frames. The magnetometer has an anti-aliasing low-pass filter on each axis. As part of the attitude control on the spacecraft, there are two magnetic torquers. At the magnetometers, these torquers can generate magnetic fields larger than the ambient fields to be measured. Therefore signals from these torquer currents need to be removed. The torquer currents are measured at the same rate as the magnetometer rate, and the currents are used to correct the magnetometer measurements.
However, the torquer currents were not low-pass filtered. As a result, large instantaneous steps in the torquer currents show up in the magnetometer data as a delayed, slowly rising wave with some ringing, just what one would expect from the magnetometer low-pass filters. The so-called "Farthing coefficients" simulate, from a short past history of the torquer measurements, the effects of the magnetometer filters. The torquer current changes are asynchronous with the telemetry frames and the timing between these events must be measured to a eighth of a telemetry frame interval for good performance. The transient responses in changes in torquer currents are reduced, but not eliminated for large changes in torquer currents.
There exists one opportunity at the beginning of each mission to perform a spacecraft rotation maneuver to determine magnetometer offsets. These offsets are used through the duration of the lifetime of each satellite.
Approximate coefficients are:
Version:2.3.1
GOES 12 magnetic field data at 0.512 s time resolution. The vector magnetic field is given in the spacecraft Earth-referenced coordinate system: Hp, He, Hn, and Ht, where Hp is perpendicular to the satellite orbital plane, or parallel to spin axis of the Earth in the case of a 0° inclination orbit, He is perpendicular to Hp and directed earthward, Hn is perpendicular to both Hp and He and directed eastward, and Ht is the total field.
This data product also provides GOES 12 satellite positions and velocities derived from SSCWEB GEI ephemeris, interpolated to 1 min time resolution.
The magnetometer data are downlinked from the spacecraft in real-time to the NOAA Space Weather Prediction Center (SWPC) in Boulder, Colorado. The data from the raw Command and Data Acquisition (CDA) telemetry stream are processed by pre-processors at SWPC and from there 1 min averages are distributed to SWPC Space Weather Operations, as well a archived at the NOAA National Geophysical Data Center (NGDC) and the NASA Coordinated Data Analysis Web (http://cdaweb.gsfc.nasa.gov/). The raw high resolution data are corrected and processed at the NOAA SWPC, and later archived at NGDC.
The major issue for processing the high resolution data is correction for the magnetic signature of spacecraft torquer currents as briefly discussed in the magnetometer instrument descriptions. In normal operation, the magnetometer samples its three axes every 0.512 s, synchronized with the telemetry frames. The magnetometer has an anti-aliasing low-pass filter on each axis. As part of the attitude control on the spacecraft, there are two magnetic torquers. At the magnetometers, these torquers can generate magnetic fields larger than the ambient fields to be measured. Therefore signals from these torquer currents need to be removed. The torquer currents are measured at the same rate as the magnetometer rate, and the currents are used to correct the magnetometer measurements.
However, the torquer currents were not low-pass filtered. As a result, large instantaneous steps in the torquer currents show up in the magnetometer data as a delayed, slowly rising wave with some ringing, just what one would expect from the magnetometer low-pass filters. The so-called "Farthing coefficients" simulate, from a short past history of the torquer measurements, the effects of the magnetometer filters. The torquer current changes are asynchronous with the telemetry frames and the timing between these events must be measured to a eighth of a telemetry frame interval for good performance. The transient responses in changes in torquer currents are reduced, but not eliminated for large changes in torquer currents.
There exists one opportunity at the beginning of each mission to perform a spacecraft rotation maneuver to determine magnetometer offsets. These offsets are used through the duration of the lifetime of each satellite.
Approximate coefficients are:
| Role | Person | StartDate | StopDate | Note | |
|---|---|---|---|---|---|
| 1. | PrincipalInvestigator DataProducer | spase://SMWG/Person/Howard.J.Singer | |||
| 2. | DataProducer | spase://SMWG/Person/Ann.Newman | |||
| 3. | DataProducer | spase://SMWG/Person/Lorne.Matheson | |||
| 4. | MetadataContact | spase://SMWG/Person/Jan.Merka |
In CDF via HTTP from CDAWeb
For CDAWeb subset, plot and list capabilities
Web Service to this product using the HAPI interface.
GEOS 12 longitude time, UTC, in seconds since 1970-01-01T00:00:00
GEOS 12 longitude epoch
Satellite geographic west longitude at noon UTC
Magnetic local time at satellite position
Satellite position vector in GEI coordinates
Satellite position vector in GSM coordinates
Satellite velocity vector in GEI coordinates
Satellite velocity vector in GSM coordinates
g12_perpendicular
Data epoch range, UTC
GEOS 12 ephemeris time, UTC, in seconds since 1970-01-01T00:00:00
GEOS 12 ephemeris epoch, UTC
GEOS 12 sample time, UTC, in seconds since 1970-01-01T00:00:00
g12_sample_epoch
Magnetic field vector samples in ENP coordinates.
Coordinate description for historically used PEN system:
Magnetic field vector samples in GEI coordinates
Magnetic field vector samples in GSM coordinates
Total magnetic field strength
Magnetotorquer T1 filtered counts. Signed counts smoothed by 3-point average, delayed, or smoothed by Farthing coefficients.
Magnetotorquer T2 filtered counts. Signed counts smoothed by 3-point average, delayed, or smoothed by Farthing coefficients.
Data Quality Flag: An integer with a value from 1 through 7 indicating data quality, with 1 and 2 being no data, and 7 being the best data.
Possible data quality values:
Commands are not always available in the telemetry, in which case, a 3-point average is done.