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 Data
 STEREO
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Earth Orbit Phase |
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Plots The magnetic field plots can be drawn in both GSM and S/C coordinates at low (1 min) resolution and at medium resolution (1s) but only in S/C coordinates at full resolution (8 sample/sec). ASCII Listings The magnetic field data can be listed in both GSM and S/C coordinates at low and medium resolution but only in S/C coordinates at full resolution. A separate web page provides access to RTN coordinates for the Heliocentric Phase.
Time Format
Data Availability
Data are available in GSM coordinates from January 1, 2007 (Day 1) to January 31, 2007 (Day 31). Correlative Data Correlative solar wind and IMF data from Wind and ACE magnetometers are also available for comparative analysis, but lag behind the availability of STEREO data because we use only Level 2 data in the Web Server. Magnetometer Description Magnetometer Description Figure 1 1 shows the IMPACT magnetometer, MAG. MAG is a triaxial fluxgate Magnetometer built at Goddard Space Flight Center to measure the vector magnetic field in two ranges up to 65,536 nT and up to 500 nT with 0.1 nT accuracy. It is a high-heritage instrument, with updated features based on the MESSENGER magnetometer design (Acuna et al., 2006). The location of the magnetometer near the end of the ~5.8 m IMPACT boom minimizes the contribution of any spacecraft fields to the measurements. In addition, a magnetics cleanliness program was enforced from the beginning of the project in order to provide a minimum cost, intrinsically clean spacecraft from a magnetics perspective. This was achieved by sensitizing instrument and spacecraft providers to materials use and design and construction practices, by screening particularly troublesome parts such as reaction wheels, and by magnetically “sniffing” the instruments from all investigations prior to their delivery as well as the spacecraft and the integrated system. In addition, magnetic field data were obtained during integration and test phases to keep track of and characterize unavoidable signatures in the MAG data from permanent instrument and spacecraft features, and during spacecraft and instrument commissioning operations. The MAG design, calibration and operation is described in detail by Acuna et al. (in preparation, 2006). The digital resolution of the 500 nT range of the IMPACT MAG is 16 pT. Signals from the fluxgate sensor are processed by the analog electronics and then fed to the IDPU for interfacing to the spacecraft. These magnetometer raw data are low pass filtered, digitized, averaged, and then formatted into a MAG telemetry packet. The magnetometer has sufficient sensitivity and dynamic range to study the magnetic fields associated with all the phases and regions of interest in the mission. The limitation of the measurements is the amount of magnetic noise introduced by the spacecraft and its instruments. The nominal accuracy of ±0.1 nT is adequate to achieve the STEREO mission science objectives for the magnetometer. The nominal time resolution of the MAG data is 8 vectors/s, though 32 Hz (~.03 s) vector data are available during the IMPACT burst mode periods described below. Planned spacecraft rolls throughout the mission allow checks on the MAG sensor offsets and calibrations. No regular commanding is needed for MAG. We note that the sensors are operating in a much colder environment than that for which they were designed. The major impact of the cold environment is a greater than expected offset from the nominal zero level. Effects on gain and orthogonality are to be assessed. |
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For more information or help concerning the contents of this page, contact: polar@igpp.ucla.edu. For more information about Space Science Center contact: www@igpp.ucla.edu. Last updated: May 22, 2007 |
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