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MMS 3 Digital Signal Processor (DSP) Search Coil Magnetometer (SCM), Magnetic Field Power Spectral Density, Level 2 (L2), Slow Mode, 16 s Data

The MMS magnetic field power spectral density (BPSD) is computed onboard by the Digital Signal Processor (DSP). The fast Fourier transform (FFT) calculation is performed on a digitized version of analog signals from the Search Coil Magnetometer (SCM) in the SCM123 coordinate system (scm1 = - x sensor; scm2 = -z sensor; scm3 = -y sensor). This data product is computed in space from individual components that are not synchronized to the 1 second pulse. Therefore, the timing between channels can be inaccurate by a fraction of a second. The samples times are interval start times taken from the x component. The spectra are calculated via a 1024-point FFT algorithm on piecewise continuous sets of waveform data. Nine signals can be processed simultaneously. Six of the twelve DC-coupled E, DC-coupled V, or SCM signals (16384 samples/s) are selected for spectral processing at 100% duty cycle. In addition, the three AC-coupled signals (262,144 kS/s) each can be processed at 6.25% duty cycle. Each of the nine signals has 16, 1024-point FFT operations every second; the field-programmable gate array (FPGA) performs 144 FFTs per second. The FFT is performed by an arithmetic logic unit (ALU), which is controlled by a state machine. Both are hard-coded into the FPGA. The operation starts by applying a 1024-point Hanning window onto a waveform. Next, an FFT is implemented. The FFT is broken into a series of "butterfly" operations performed by the ALU. The result has real and imaginary data. Power spectra are calculated by taking the sum of squares of real and imaginary values (the ALU includes a multiplier), which produces a power spectrum with 512 frequency bins. The frequency bins are then combined to give pseudo-logarithmic frequency spacing (del f)/f. The spectra are reduced to 88 frequency bins with (del f)/f between 6% and 12% when possible. Narrow-band emissions can be fit to an accuracy of (del f)/f ~3%, allowing for an accurate determination of plasma density. The spectra can be averaged in time. The fastest reporting rate of any signal is 16 spectra per second. Reporting rates can be as slow a one spectra every 16 s (averaging 256 spectra). The averaging process has 48-bit accuracy to maximize the dynamic range. The amplitudes undergo a pseudo-logarithmic compression to an 8-bit number representing over 120 dB of dynamic range at ~5% precision.

Romo (ROE) Ground-based Vector Magnetic Field (L2) 1.0 min Data

Romo, Denmark, Ground-based Vector Magnetic Field Level 2 Data, 1.0 min Time Resolution, Station Code: (ROE), Station Location: (GEO Latitude 55.2, Longitude 8.6), DTU Network

Repulse Bay (RBAY/RBY) Ground-based Vector Magnetic Field (L2) 0.5 s Data

Repulse Bay, NU, Ground-based Vector Magnetic Field Level 2 Data, 0.5 s Time Resolution, Station Code: (RBAY/RBY), Station Location: (GEO Latitude 66.5, Longitude 273.8), MACCS Network

Voyager 1 9.6-s Averaged Triaxial Fluxgate Magnetometer (MAG) Interplanetary Magnetic Field in CDF Format

This data set includes the Voyager spacecraft number (1 or 2), the date-time in decimal year (90.00000 is day 1 of 1990), the magnetic field strength, F1, computed from high-resolution magnitudes, the elevation and azimuth angles in heliographic (RTN) coordinates, and the magnetic field strength, F2, computed from 1-hr averages of the components. The vector components of B can be computed from F2 and the two angles. The elevation angle is the latitude angle above or below the solar equatorial plane, and the azimuth angle is in the direction orbital motion around the Sun from the projection of the Sun-to-spacecraft axis into the solar equatorial plane. The Voyager MAG experiment and coordinates are further described in the following publication: Behannon, K.W., M.H. Acuna, L.F. Burlaga, R.P. Lepping, N.F. Ness, and F.M. Neubauer, Magnetic-Field Experiment for Voyager-1 and Voyager-2, Space Sci. Rev., 21 (3), 235-257, 1977. At the time of experiment proposal, it was expected that the required accuracy of the measurements would be 0.1 nT, determined by the combined noise of the sensors and the spacecraft field. The spacecraft magnetic field at the outboard magnetic field sensor, referred to as the primary unit, was expected to be 0.2 nT and highly variable, consistent with current estimates. Hence, the dual magnetometer design (Ness et al., 1971, 1973; Behannon et al., 1977). At distances > 40 AU, the heliospheric magnetic fields are generally much weaker than 0.4 nT; the average magnetic field strength near 40 AU and 85 AU is about 0.15 nT and 0.05 nT, respectively. The use of roll calibrations lasting about 6 hours permits determination of the effective zero levels for the two independent magnetic axes that are perpendicular to the roll axis, which is nearly parallel to the radius vector to the Sun, at intervals of about 3 months. There is no roll calibration for the third magnetic axis. Comparison of the two derived magnetic vectors from the two magnetometers permits validation of the primary magnetometer data with an accuracy of 0.02 to 0.05 nT. A discussion of the uncertainties that must be considered when using these data is given in the Appendix of Burlaga et al. (1994) and in Appendix A of Burlaga et al. (2002). References: Behannon, K.W., M.H. Acuna, L.F. Burlaga, R.P. Lepping, N.F. Ness, and F.M. Neubauer, Magnetic-Field Experiment for Voyager-1 and Voyager-2, Space Science Reviews, 21 (3), 235-257, 1977. Burlaga, L.F., Merged interaction regions and large-scale magnetic field fluctuations during 1991 - Voyager-2 observations, J. Geophys. Res., 99 (A10), 19341-19350, 1994. Burlaga, L.F., N.F. Ness, Y.-M. Wang, and N.R. Sheeley, Jr., Heliospheric magnetic field strength and polarity from 1 to 81 AU during the ascending phase of solar cycle 23, J. Geophys. Res., 107 (A11), 1410, 2002. Ness, N., K.W. Behannon, R. Lepping, and K.H. Schatten, J. Geophys. Res., 76, 3564, 1971. Ness et al., 1973. Coordinate Systems: Interplanetary magnetic field studies make use of two important coordinate systems, the Heliographic Inertial (HGI) coordinate system and the Heliographic (HG) coordinate system. The HGI coordinate system is used to define the spacecraft's position. The HGI system is defined with its origin at the Sun. There are three orthogonal axes, X(HGI), Y(HGI), and Z(HGI). The Z(HGI) axis points northward along the Sun's spin axis. The X(HGI)-Y(HGI) plane lays in the solar equatorial plane. The intersection of the solar equatorial plane with the ecliptic plane defines a line, the longitude of the ascending node, which is taken to be the X(HGI) axis. The X(HGI) axis drifts slowly with time, approximately one degree per 72 years. The magnetic field orientation is defined in relation to the spacecraft. Drawing a line from the Sun's center (HGI origin) to the spacecraft defines the X axis of the HG coordinate system. The HG coordinate system is defined with its origin centered at the spacecraft. Three orthogonal axes are defined, X(HG), Y(HG), and Z(HG). The X(HG) axis points radially away from the Sun and the Y(HG) axis is parallel to the solar equatorial plane and therefore parallel to the X(HGI)-Y(HGI) plane as well. The Z(HG) axis is chosen to complete the orthonormal triad. An excellent reference guide with diagrams explaining the HGI and HG systems may be found in L.F. Burlaga, MHD Processes in the Outer Heliosphere, Space Sci. Rev., 39, 255-316, 1984.

Kullorsuaq (KUV) Ground-based Vector Magnetic Field (L2) 1.0 min Data

Kullorsuaq, Greenland, Ground-based Vector Magnetic Field Level 2 Data, 1.0 min Time Resolution, Station Code: (KUV), Station Location: (GEO Latitude 74.6, Longitude 302.8), DTU Network

Poker Flat (POKR) Ground-based Vector Magnetic Field (L2) 0.5 s Data

Poker Flat, AK, Ground-based Vector Magnetic Field Level 2 Data, 0.5 s Time Resolution, Station Code: (POKR), Station Location: (GEO Latitude 65.1, Longitude 212.6), University of Alaska Network

Voyager 1 48-s Triaxial Fluxgate Magnetometer (MAG) Magnetic Field Data Near and Beyond Termination Shock in CDF Format

The main science objectives for the Voyager Interplanetary Mission, VIM, are as follows: - investigate the structure of the solar wind magnetic fields and plasma in the inner and outer heliosphere; - conduct long term study of heliospheric evolution during different phases of the 22-year solar magnetic cycle and the 11-year solar activity cycle; - study the long term solar modulation and determine the elemental and isotopic abundances of galactic cosmic ray particles in the heliosphere; - measure radial gradients, spectra, and nuclear abundances of the anomalous component of cosmic rays from acceleration at the solar wind termination shock; - investigate local particle acceleration in the interplanetary medium from solar flare shocks and corotating interaction regions; - study propagation of solar energetic particles in the heliosphere. The average magnetic field strength produced by the spacecraft at the location of the outboard magnetometer of the dual magnetometers system on Voyager 1 and Voyager 2 is about 0.1-0.2 nT, comparable to the most probable magnetic field strength in the inner heliosheath and significantly larger than the most probable magnetic field strength in the distant supersonic solar wind. The spacecraft magnetic field is a complex, time-dependent signal that must be removed from the measured magnetic field signal in order to derive the ambient magnetic fields of the solar wind and heliosheath. Corrections must also be made for spurious magnetic signals and noise associated with the telemetry system, ground tracking systems, and other factors. Extracting the signal describing the solar wind and heliosheath from the many sources of uncertainty is a complex and partly subjective process that requires understanding of the instrument and judgement based on experience in dealing with the ever-changing extraneous signals. We estimate that for the Voyager magnetic field data the 1-sigma the uncertainty of the 48-s averages for each of the components of the magnetic field BR, BT, and BN is typically +/- 0.02 nT; the uncertainty in magnitude F1 is typically +/- 0.03 nT. F1, BR, BT, and BN can differ from one another and they may vary with time, but there is no practical way to determine these uncertainties more precisely at present. References: D.B. Berdichevsky, Voyager Mission, Detailed processing of weak magnetic fields; I - Constraints to the uncertainties of the calibrated magnetic field signal in the Voyager missions, 2009; https://vgrmag.gsfc.nasa.gov/Berdichevsky-VOY_sensor_opu090518.pdf Behannon, K.W., M.H. Acuna, L.F. Burlaga, R.P. Lepping, N.F. Ness, and F.M. Neubauer, Magnetic-Field Experiment for Voyager-1 and Voyager-2, Space Science Reviews, 21 (3), 235-257, 1977. Burlaga, L.F., Merged interaction regions and large-scale magnetic field fluctuations during 1991 - Voyager-2 observations, J. Geophys. Res., 99 (A10), 19341-19350, 1994. Burlaga, L.F., N.F. Ness, Y.-M. Wang, and N.R. Sheeley Jr., Heliospheric magnetic field strength and polarity from 1 to 81 AU during the ascending phase of solar cycle 23, J. Geophys. Res., 107 (A11), 1410, 2002. Ness, N., K.W. Behannon, R. Lepping, and K.H. Schatten, J. Geophys. Res., Spacecraft studies of the interplanetary magnetic field, 76, 3564, 1971.

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SAKIGAKE INTERPLANETARY MAGNETIC FIELD DATA V 1.0

The original Data Set Name was MST5IMF. The data was delivered personally by Oyama. The component values indicate a crossing of the neutral sheet. The magnetic field is defined in terms of solar ecliptic coordinates with spacecraft at the center and the x direction positive towards the Sun, the y direction in the ecliptic plane, and the z direction given by a left handed coordinate system. A total force value is also given.

Kaktovik (KAKO) Ground-based Vector Magnetic Field (L2) 1.0 s Data

Kaktovik, AK, Ground-based Vector Magnetic Field Level 2 Data, 1.0 s Time Resolution, Station Code: (KAKO), Station Location: (GEO Latitude 70.1, Longitude 216.4), University of Alaska Network

Nuuk (GHB) Ground-based Vector Magnetic Field (L2) 1.0 min Data

Nuuk (Godthap), Greenland, Ground-based Vector Magnetic Field Level 2 Data, 1.0 min Time Resolution, Station Code: (GHB), Station Location: (GEO Latitude 64.2, Longitude 308.3), DTU Network

Pioneer 10 hourly merged magnetic field and plasma data

This is an hourly resolution, merged magnetic field and plasma data set created at NSSDC for COHOWeb. Magnetic field vectors and plasma flow direction angles are given in RTN coordinates. Spacecraft position data are given in Heliographic inertial (HGI coordinates).

Harris (HRIS) Ground-based Vector Magnetic Field (L2) 0.5 s Data

Harris, MN, Ground-based Vector Magnetic Field Level 2 Data, 0.5 s Time Resolution, Station Code: (HRIS), Station Location: (GEO Latitude 45.6, Longitude 93.0), THEMIS GBO Network

Tiksi (TIK) Ground-based Vector Magnetic Field (L2) 1.0 min Data

Tiksi, Russia, Ground-based Vector Magnetic Field Level 2 Data, 1.0 min Time Resolution, Station Code: (TIK), Station Location: (GEO Latitude 71.6, Longitude 128.9), AARI Network

Wind Magnetic Field Investigation (MFI) Composite Data

Wind MFI composite data in GSE and GSM coordinates. The files contain multiple time resolution data: 3-second, 1-minute, and 1-hour. Final Version 5 data are accessible to within about 3 months of current date, newly defined Version 4 data (with final Bz offsets and not-yet-final spacecraft position vectors) between 3 months and about 2 weeks of current date, and newly defined Version 3 data (with the most recently determined Bz offset value, not yet final for the Version 3 interval) from 2 weeks to about 2 days of current.

Igloolik (IGLO/IGL) Ground-based Vector Magnetic Field (L2) 0.5 s Data

Igloolik, NU, Ground-based Vector Magnetic Field Level 2 Data, 0.5 s Time Resolution, Station Code: (IGLO/IGL), Station Location: (GEO Latitude 69.3, Longitude 278.2), MACCS Network

Pioneer 10 Helium Vector Magnetometer (MAG), Magnetic Field in RTN Coordinates and One Way Light Time Delays, Cruise Phase

This Data Set from the Pioneer 10 Helium Vector Magnetometer, HVM, consists of 1 min Averages of Vector Components and Scalar Magnitudes of the Interplanetary Magnetic Field. The three Components, Br, Bt, Bn, are given in Radial-Tangential-Normal, RTN, Coordinates and all Magnetic Fields are expressed in nT. The Scalar Magnitudes, B, are Averages of higher-resolution Scalar Magnitudes. The Time Tag for each 1 min Interval is the Midpoint of the averaging Interval in Spacecraft Event Time-UT, SCET-UT. The Averages were originally calculated over 1 min Intervals in Ground Received Time, and the Midpoints have been converted to SCET-UT. The File P10_LIGHTTIME contains Daily Values for the one way Light Time Delay. No records are written for Data Gaps. Most Files cover from 28 up to 35 Days, but there are a Number of shorter Files, particularly at Year Boundaries. Data for the Jupiter Encounter, Days 329 through 349 of 1973, are not included. The RTN System is fixed to the Sun-Spacecraft Line and aligned with the Solar Heliographic Equator. The R Axis is the Radial Direction to the Spacecraft, the T Axis is the Cross Product of the Solar Rotation Axis and the R Axis, and N is the Cross Product of the R and T Axes. The File P10HVM_15M.SFD provides a detailed Description of the Pioneer Spacecraft, the HVM Experiment, and the Data. This ASCII Document is written in Standard Formatted Data Unit, SFDU, Format as Part of NSSDC Data Set 72-012A-01I for 15 min. Averaged Data covering 1972-03-03 to 1975-11-17. Data Set Files: P10HVMMN_FMT.txt, this Document, ASCII; P10HVM_15M.SFD, SFDU Metadata Extract from Pioneer 10 HVM 15 min Data Set; Myyddd.asc, 1 min Data Files from Pioneer 10 HVM starting at Date yyddd; and P10_LIGHTTIME.asc, Data File with One Way Light Time Delays, ASCII. Related Information and Data: Further Details on the Spacecraft, Experiment, Data Sets at NSSDC, and related WWW Sites can be found on the Pioneer 10/Pioneer 11 Flight Project Page under https://nssdc.gsfc.nasa.gov/space/. Pioneer 10 and Pioneer 11 Hourly of the Interplanetary Solar Wind Data Averages and Heliocentric Coordinates and other Interplanetary Spacecraft may be also be accessed and plotted Online through the COHOWeb Service, https://cohoweb.gsfc.nasa.gov/coho/. Pioneer Data on the NASA Data Archive and Distribution Service, NDADS, may be located on the WWW via the SPyCAT Service at the first URL listed above or by an E-Mail Message to the Automated Retrieval Mail System, ARMS, at archives@ndadsa.gsfc.nasa.gov with $apos;HOLDINGS$apos; on the Subject Line. Data Set Coverage, yyyy-mm-dd: 1972-03-03 to 1975-11-17, Data Set Contact: Joyce Wolf, NASA JPL.

ISEE 3 Vector Helium Magnetometer (MAG), Magnetic Field, 1 min CDF Data

This Data Set contains averaged 1 min magnetic field data converted from simple ASCII records. It was created at the NSSDC from a more complex, multi-resolution data set with the current NSSDC ID of SPHE-00673 and old NSSDC ID of 78-079A-02D, provided by the Principal Investigator Team and now available from ftps://spdf.gsfc.nasa.gov/pub/data/isee/isee3/magnetic_fields/1min_ascii_extracted/. The Coordinate System for the magnetic field components is the JPL-defined I,S Coordinate System set at the origin at the spacecraft: I is the unit vector in the direction of the ISEE 3 spin axis, positive in the northward direction, and S is the unit vector from the spacecraft to the sun. The Z-Axis is parallel to I, the Y-Axis is parallel to the cross product I ⨯ S, and the X-Axis is parallel to Y ⨯ Z. The I,S coordinate system is approximately the same as the Solar Ecliptic, SE, System since the Spacecraft Z-Axis, the Spin Axis, is maintained within 0.5° of perpendicular to the Ecliptic Plane. The SE coordinate system is defined in the same way as GSE, but with the spacecraft point of observation substituted for the position of the earth. For years 1984 through 1990 the spacecraft position in HGI coordinates was added to the data product. The HGI coordinate system is sun-centered and inertially fixed with respect to an X-Axis directed along the intersection line of the Ecliptic and Solar Equatorial planes, which defines the 0° longitude direction. The Solar Equatorial plane is inclined at 7.25° from the Ecliptic. This direction was towards an Ecliptic longitude equal to 74.367° on January 1, 1900 at 12:00 UT, but because of the precession of the earth's equator, this longitude increases by 1.4° per century. The Z-Axis is directed perpendicular to and northward of the solar equator and the Y-Axis completes the right-handed Set. The HGI longitude increase from 0° in the X-Direction towards the positive Y-Direction. The HGI latitude increases to +90° at the north pole and decreases to -90° at the south pole. Note that the values listed are 1 min averages, so that B ^2 may not equal B^2 .

Fort Nelson (FTN) Ground-based Vector Magnetic Field (L2) 1.0 s Data

Fort Nelson, BC, Ground-based Vector Magnetic Field Level 2 Data, 1.0 s Time Resolution, Station Code: (FTN), Station Location: (GEO Latitude 58.9, Longitude 237.2), STEP Polar Network

Upernavik (UPN) Ground-based Vector Magnetic Field (L2) 1.0 min Data

Upernavik, Greenland, Ground-based Vector Magnetic Field Level 2 Data, 1.0 min Time Resolution, Station Code: (UPN), Station Location: (GEO Latitude 72.8, Longitude 303.8), DTU Network

STEREO-B In-Situ Measurements of Particles and CME Transients (IMPACT) Fluxgate Magnetometer (MAG) Magnetic Field Vectors, in Spacecraft (SC) Coordinates

STEREO Behind In-situ Measurements of Particles and CME Transients, IMPACT, Magnetometer Instrument, MAG, Magnetic Field Vectors, Level 1 Data