Description of the data file structure in [SPASE] format [SPASE]: <https://doi.org/10.48322/E72C-5Y75> "Space Physics Archive Search and Extract (SPASE) Base Information Model, 2021, SPASE Group"
SPASE Metadata (NumericalData)
AZUR
Radiation Belts
AP-8 MAX
Heynderickx, D., & Kruglanski, M. (2026). AZUR/EI-88: Medium-energy low-altitude trapped proton and alpha-particle data (1969–1970) (Version 1) [Dataset]. Royal Belgian Institute for Space Aeronomy. https://doi.org/10.18758/40T59LOB
## AZUR The magnetically aligned spacecraft AZUR (also called GRS-A), launched into a near-polar orbit on 08 Nov 1969, was a product of a joint effort by NASA-GSFC and the German _Bundesministerium fuer Wissenschaftliche Forschung_ (BMWF) and had as its primary purpose the acquisition of terrestrial radiation belt data. The instrument complement included detectors to measure the directional and omnidirectional fluxes of protons and electrons. These instruments and the high quality of the resulting measurements made the AZUR mission particularly well suited for the study of the trapped radiation environment, despite the short duration of the mission. ## Experiment EI-88 The energetic proton measurements, which were collected during the maximum of Solar Cycle 20, were the basis for the low altitude part of the NASA model AP-8 MAX [Sawyer & Vette, 1976]. The payload consisted of seven instruments. Descriptions of each instrument package can be found in [Achtermann et al., 1970] (see also [Hovestadt et al., 1972]). The EI-88 experiment consisted of two identical proton-alpha particle telescopes, one oriented perpendicular and one oriented at 45 degrees with respect to the local magnetic field vector. In the northern hemisphere, the 45 degree telescope pointed upwards. The telescopes detected protons and alpha particles in the Earth's trapping region. Unfortunately, the data gathered after 5 March 1970 have been lost. __Principal Investigator__: D.K. Hovestadt, Max Planck Institut fuer Extra-Terrestrische Physik ## Dataset In the framework of the ESA/ESTEC [TREND-2] study, D. Heynderickx restored the data from the original NSSDC magnetic tapes [69-097A-02A,04A], performed detailed data checks and removed bad and suspicious data records. In the framework of the ESA/ESTEC [TREND-3] study, magnetic parameters were computed using [UNILIB]. ## Acknowledgment * National Space Science Data Center, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. * D.K. Hovestadt, Max Planck Institut fuer Extra-Terrestrische Physik * ESA/ESTEC TREND studies [TREND-2]: <https://doi.org/10.18758/A_393> "TREND-2 Trapped Radiation Environment Model Development - Final Report, Aeronomica Acta, Issue 393, 1995, J. Lemaire, A.D. Johnstone, D. Heynderickx, D.J. Rodgers, S. Szita, V. Pierrard" [TREND-3]: <https://orfeo.belnet.be/handle/internal/6606> "TREND-3 Radiation Environments of Astronomy Missions and LEO Missions - Final Report, 1998, J. Lemaire, D. Heynderickx, M. Kruglanski, A.D. Johnstone, D.J. Rodgers, S. Szita, G. Jones, E. Keppler, R. Friedel, G. Loidl" [Achtermann et al., 1970]: <https://julib.fz-juelich.de/vufind/Record/64778> "Die Experimente EI 88 und EI 93 zur Messung von energiereichen Elektronen, Protonen und Alphateilchen im Satelliten AZUR: Physikalische Eigenschaften und Testmessungen, E. Achtermann, B. Häusler, D. Hovestadt, G. Paschmann, E. Künneth, P. Laeverenz, 1970, BMBW-FBW 70-67, Bundesministerium für Bildung und Wissenschaft Forschungsbericht (ISSN 0170-6144)." [Hovestadt et al., 1972]: <https://doi.org/10.1007/978-94-010-2896-7_11> "New Observations of the Proton Population of the Radiation Belt Between 1.5 and 104 Mev., D. Hovestadt, E. Achtermann, B. Ebel, B. Häusler, G. Paschmann, 1972, in McCormac, B.M. (eds) Earth’s Magnetospheric Processes. Astrophysics and Space Science Library, vol 32. Springer" [69-097A-02A,04A]: <https://spdf.gsfc.nasa.gov/pub/data/azur/proton-electron_detector/particle_count_rates/grs-a_count-rates_69-097a-02a-04a_DSC_0244.pdf> "NSSDC, Tape 69-097A-02A,04A, GRS-A Particle Count Rates" [Sawyer & Vette, 1976]: <https://ntrs.nasa.gov/citations/19770012039> "AP-8 trapped proton environment for solar maximum and solar minimum, D.M. Sawyer, J.I. Vette, December 1976, Report NSSDC/WDC-A-R/S-76-06, NSSDC" [UNILIB]: <https://orfeo.belnet.be/handle/internal/6593> "TREND-3 Technical Note 10: UNIRAD Improvements and Subroutine Library, D. Heynderickx, M. Kruglanski, 1998"
AZUR/EI-88: Medium-energy low-altitude trapped proton and alpha-particle data (1969–1970)
Dataset generated in the framework of the ESA/ESTEC TREND-2 and TREND-3 studies (contract No 9828/92/NL/FM and 11711/95/NL/JG)
Royal Belgian Institute for Space Aeronomy
Koninklijk Belgisch Instituut voor Ruimte-Aeronomie
Institut royal d'Aéronomie Spatiale de Belgique
The file includes 230,974 records and one header lines. Each record includes 35 fields: ### `cdf_epoch` (column 01) [CDF] Epoch, milliseconds since year 0 (proleptic Gregorian calendar with astronomical year numbering). ### `epoch` (column 02) Epoch in [RFC3339] format. ### `quality` (column 03) Original data quality flag (0: _good_; 1: _average_; 2: _bad_). ### `position_gei_x`, `position_gei_y`, `position_gei_z` (columns 04-06) Satellite position in Geocentric Equatorial Inertial (GEI) Cartesian coordinates (x, y, z), in km. ### `b_meas_bx`, `b_meas_by`, `b_meas_bz` (columns 07-09) Measured magnetic field components (x,y,z), in Gauss. ### `fpdu_1_1.5-2.7`, `fpdu_1_2.7-5.2`, `fpdu_1_5.2-10.4`, `fpdu_1_10.4-22.0`, `fpdu_1_22.4-48.8`, `fpdu_1_48.8-104.0` (columns 10-15) Differential directional proton fluxes measured by the telescope oriented perpendicular with respect to the local magnetic field vector, in cm⁻² s⁻¹ sr⁻¹ MeV⁻¹, for the six energy channels * 1.5 - 2.7 MeV * 2.7 - 5.2 MeV * 5.2 - 10.4 MeV * 10.4 - 22.0 MeV * 22.4 - 48.8 MeV * 48.8 - 104.0 MeV ### `fpdu_2_1.5-2.7`, `fpdu_2_2.7-5.2`, `fpdu_2_5.2-10.4`, `fpdu_2_10.4-22.0`, `fpdu_2_22.4-48.8`, `fpdu_2_48.8-104.0` (columns 16-21) Differential directional proton fluxes measured by the telescope oriented at 45° with respect to the local magnetic field vector (in the northern hemisphere, the telescope pointed upwards), in cm⁻² s⁻¹ sr⁻¹ MeV⁻¹, for the six energy channels * 1.5 - 2.7 MeV * 2.7 - 5.2 MeV * 5.2 - 10.4 MeV * 10.4 - 22.0 MeV * 22.4 - 48.8 MeV * 48.8 - 104.0 MeV ### `fadu_1_6.0-19.0` (column 22) Differential directional alpha flux measured by the 90° telescope, in cm⁻² s⁻¹ sr⁻¹ MeV⁻¹. Energy range: 6.0 - 19.0 MeV. ### `fadu_2_6.0-19.0` (column 23) Differential directional alpha flux measured by the 45° telescope, in cm⁻² s⁻¹ sr⁻¹ MeV⁻¹. Energy range: 6.0 - 19.0 MeV. ### UNILIB data (columns 24-35) Magnetic field related coordinates computed with [UNILIB] for both telescopes using a combination of the International Geomagnetic Reference Field (IGRF) and the [Olson & Pfitzer quiet] external magnetic field. * `unilib_bm_1`, `unilib_bm_2` (columns 24-25): Magnetic field intensity Bm at the mirror points, in nT. * `unilib_i_1`, `unilib_i_2` (columns 26-27): Integral invariant function _I_, in Earth radii (Re, 6,371.2 km). * `unilib_l_1`, `unilib_l_2` (columns 28-29): [McIlwain]'s _L_ parameter, in Earth radii. * `unilib_l_star_1`, `unilib_l_star_2` (columns 30-31): [Roederer]'s _L_* shell parameter, in Earth radii. * `unilib_alpha_eq_1`, `unilib_alpha_eq_2` (columns 32-33): Equatorial pitch angle, in degree. * `unilib_b_eq` (column 34): Equatorial magnetic field strength, in nT. * `unilib_mlt` (column 35): Magnetic Local Time, in hours. [CDF]: <https://cdf.gsfc.nasa.gov/> "NASA/SPDF Common Data Format" [RFC3339]: <https://doi.org/10.17487/RFC3339> "Date and Time on the Internet: Timestamps, G. Klyne, C. Newman, July 2002, RFC 3339" [UNILIB]: <https://orfeo.belnet.be/handle/internal/6593> "TREND-3 Technical Note 10: UNIRAD Improvements and Subroutine Library, D. Heynderickx, M. Kruglanski, 1998" [Olson & Pfitzer quiet]: <https://www.osti.gov/biblio/7212748> "Magnetospheric magnetic field modeling, W.P. Olson, K. A. Pfitzer, 1977, Annual Scientific Report, AFOSR Contract No. F44620-75-C-0033" [McIlwain]: <https://doi.org/10.1029/JZ066i011p03681> "Coordinates for Mapping the Distribution of Magnetically Trapped Particles, C.E. McIlwain, J. Geophys. Res., 66, pp. 3681-3691, 1961" [Roederer]: <https://doi.org/10.1007/978-3-642-49300-3> "Dynamics of Geomagnetically Trapped Radiation, J. G. Roederer, Springer-Verlag, 1970"
Dataset AZUR/EI-88