2.2.2 spase://VMO/NumericalData/GOES/11/MAG/PT0.512S GOES 11 high-resolution magnetometer data 2011-07-19T21:41:00Z GOES 11 magnetic field data at 0.512 second time resolution. The vector magnetic field is given in the spacecraft (s/c) earth-referenced coordinate system: Hp, He, Hn, and Ht, where Hp is perpendicular to the satellite orbital plane, or parallel to Earth's spin axis in the case of a zero degree inclination orbit; He is perpendicular to Hp and directed earthwards; Hn is perpendicular to both Hp and He and directed eastwards; and Ht is the total field. This data product also provides GOES 11 satellite positions and velocities derived from SSCWEB GEI ephemeris, interpolated to one minute time resolution. The magnetometer data are downlinked from the spacecraft in real-time to the NOAA Space Weather Prediction Center (SWPC) in Boulder, CO. The data from the raw Command and Data Acquisition (CDA) telemetry stream are processed by pre-processors at SWPC and from there 1-minute averages are distributed to SWPC Space Weather Operations, as well a archived at NOAA’s National Geophysical Data Center (NGDC) and NASA’s Coordinated Data Analysis Web (http://cdaweb.gsfc.nasa.gov/). The raw high-resolution data are corrected and processed at NOAA’s 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 seconds, 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 each satellite's lifetime. Approximate coefficients are: * 0.8 milliampere per torquer current count * 4 counts per torquer current command step (3.2 milliampere per command step) * 410 milliamperes full scale current * 32 magnetometer counts per nT (approximate) * 8 torquer step counts can be up to approximately 0.5 nT (depends on axis, which torquer, which satellite, etc.) NASA Contract NAS5-02099 spase://SMWG/Person/Howard.J.Singer PrincipalInvestigator DataProducer spase://SMWG/Person/Ann.Newman DataProducer spase://SMWG/Person/Lorne.Matheson DataProducer spase://SMWG/Person/Jan.Merka MetadataContact README document http://themis.ssl.berkeley.edu/data/goes/GOES8-12_readme_draft090108.doc Notes on GOES 8-12 magnetometer data by Howard J. Singer. spase://VMO/NumericalData/GOES11/MAG/PT0.512S spase://SMWG/Repository/UCB/THEMIS GOES 11 Level2 0.512S Magnetic Field Data http://themis.ssl.berkeley.edu/data/goes/mag/g11/l2/ CDAWeb http://cdaweb.gsfc.nasa.gov/ G11_L2_MAG For CDAWeb subset, plot and list capabilities CDF None spase://SMWG/Instrument/GOES/11/MAG MagneticField Ephemeris 2007-09-15T23:59:58 2008-06-30T23:59:58 PT0.512S Earth.Magnetosphere.Main Note that magnetic field values have been replaced with missing data values during calibration periods. Also, note that there can be small jumps in the data (typically < 1 nT) when the torquer counts go through 0. The magnitude of the effect can be different for different spacecraft. GOES 8-12 spacecraft are 3-axis stabilized and there is only one opportunity for a spin maneuver at the beginning of the mission to determine on-orbit offsets. There are additional complications that result from needing to know the changing offsets introduced by torquer coils on the satellites. Though comparisons of data to model fields during quiet times, we are doing rather well with the offsets, but it is not possible to give an exact number for the accuracy. We continue to look at comparisons of data and models, and data to other nearby spacecraft encounters. We are interested in anything learned by the user, or working with the user to help interpret the data, or to answer questions. While we have put in a significant effort to remove the effects of torquer coil interference, in the 0.512 s data there can be small, typically less than 1 nT spikes in the data at the time of torquer current changes. More information on this topic is included the more extensive “readme file.” This file is a living document that will be updated periodically. g11_longitude_time g11_longitude_time GEOS 11 longitude time, UTC, in seconds since 01-Jan-1970 00:00:00 Unleaped seconds P1D s 0.0 5.0E9 NaN Temporal g11_longitude_epoch g11_longitude_epoch GEOS 11 longitude epoch P1D 01-Jan-2001 00:00:00.000 31-Dec-2100 23:59:59.999 31-Dec-9999 23:59:59.999 Temporal g11_longitude g11_longitude Satellite geographic west longitude at noon UTC P1D deg Spherical GEO -180.0 180.0 NaN DirectionAngle.AzimuthAngle Positional g11_mlt g11_mlt Magnetic local time at satellite position PT1M hours (g11_mlt - 12)*15>deg Spherical SM 0.0 24.0 NaN DirectionAngle.AzimuthAngle Positional g11_pos_gei g11_pos_gei Satellite position vector in GEI coordinates PT1M km Cartesian GEI 3 X, GEI Component.I 1 Y, GEI Component.J 2 Z, GEI Component.K 3 -1000000.0 1000000.0 NaN Vector Positional g11_pos_gsm g11_pos_gsm Satellite position vector in GSM coordinates PT1M km Cartesian GSM 3 X, GSM Component.I 1 Y, GSM Component.J 2 Z, GSM Component.K 3 -1000000.0 1000000.0 NaN Vector Positional g11_vel_gei g11_vel_gei Satellite velocity vector in GEI coordinates PT1M km/s Cartesian GEI 3 Vx, GEI Component.I 1 Vy, GEI Component.J 2 Vz, GEI Component.K 3 -1000.0 1000.0 NaN Vector Velocity g11_vel_gsm g11_vel_gsm Satellite velocity vector in GSM coordinates PT1M km/s Cartesian GSM 3 Vx, GSM Component.I 1 Vy, GSM Component.J 2 Vz, GSM Component.K 3 -1000.0 1000.0 NaN Vector Velocity g11_perp g11_perp g11_perpendicular PT1M Cartesian GEI 3 Px, GEI Component.I 1 Py, GEI Component.J 2 Pz, GEI Component.K 3 -1.0 1.0 NaN Vector Other range_epoch range_epoch Data epoch range, UTC ms 1e-3>s 01-Jan-1990 00:00:00.000 31-Dec-2029 23:59:59.999 31-Dec-9999 23:59:59.999 Temporal g11_ephem_time g11_ephem_time GEOS 11 ephemeris time, UTC, in seconds since 01-Jan-1970 00:00:00 Unleaped seconds PT1M s 0.0 5.0E9 NaN Temporal g11_ephem_epoch g11_ephem_epoch GEOS 11 ephemeris epoch, UTC PT1M 01-Jan-2001 00:00:00.000 31-Dec-2100 23:59:59.999 31-Dec-9999 23:59:59.999 Temporal g11_sample_time g11_sample_time GEOS 11 sample time, UTC, in seconds since 01-Jan-1970 00:00:00 Unleaped seconds PT0.512S s 0.0 5.0E9 NaN Temporal g11_sample_epoch GEOS 11 sample epoch, UTC g11_sample_epoch PT0.512S 01-Jan-2001 00:00:00.000 31-Dec-2100 23:59:59.999 31-Dec-9999 23:59:59.999 Temporal g11_b_enp g11_b_enp Magnetic field vector samples in ENP coordinates. Coordinate description for historically used PEN system: * Hp:  magnetic field vector component, points northward, perpendicular to orbit plane which for a zero degree inclination orbit is parallel to Earth's spin axis. * He:  magnetic field vector component, perpendicular to Hp and Hn and points earthward. * Hn:  magnetic field vector component, perpendicular to Hp and He and points eastward. * Ht:  total field PT0.512S nT 1e-9>T Cartesian 3 He, LH-ENP (sat to earth) Component.I 1 Hn, LH-ENP (east, in plane) Component.J 2 Hp, LH-ENP (perpendicular to plane) Component.K 3 -1000000.0 1000000.0 NaN Vector Magnetic g11_b_gei g11_b_gei Magnetic field vector samples in GEI coordinates PT0.512S nT 1e-9>T Cartesian GEI 3 Bx, GEI Component.I 1 By, GEI Component.J 2 Bz, GEI Component.K 3 -1000000.0 1000000.0 NaN Vector Magnetic g11_b_gsm g11_b_gsm Magnetic field vector samples in GSM coordinates PT0.512S nT 1e-9>T Cartesian GSM 3 Bx, GSM Component.I 1 By, GSM Component.J 2 Bz, GSM Component.K 3 -1000000.0 1000000.0 NaN Vector Magnetic g11_b_tot g11_b_tot Total magnetic field strength PT0.512S nT 1e-9>T -1000000.0 1000000.0 NaN Magnitude Magnetic g11_t1_counts g11_t1_counts Magnetotorquer T1 filtered counts. Signed counts smoothed by 3-point average, delayed, or smoothed by Farthing coefficients. PT0.512S counts -1000000.0 1000000.0 NaN Other g11_t2_counts g11_t2_counts Magnetotorquer T2 filtered counts. Signed counts smoothed by 3-point average, delayed, or smoothed by Farthing coefficients. PT0.512S counts -1000000.0 1000000.0 NaN Other g11_dataqual g11_dataqual 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: * 0=no satellite data * 1=no Magnetometer data * 2=satellite is in storage (spinning) mode or non-standard attitude * 3=satellite is in calibration mode * 4=3-pt averaging failed * 5=torquer value not adjusted for commands * 6=smoothed with commands but not with Farthing coefficients * 7=best quality: smoothed with commands and Farthing coefficients Commands are not always available in the telemetry, in which case, a 3-point average is done. PT0.512S none 0 7 4294967295 Other