Issue |
A&A
Volume 699, July 2025
|
|
---|---|---|
Article Number | A236 | |
Number of page(s) | 7 | |
Section | Astronomical instrumentation | |
DOI | https://doi.org/10.1051/0004-6361/202554731 | |
Published online | 14 July 2025 |
The Solar Orbiter merged magnetic field
1
LPC2E UMR7328, OSUC-University of Orléans-CNRS-CNES,
3A avenue de la recherche scientifique,
Orléans,
France
2
Department of Physics, Imperial College London,
SW7 2AZ
London,
UK
3
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris,
Meudon,
France
4
LPP UMR7648, CNRS, Ecole Polytechnique, Sorbonne Université, Observatoire de Paris, Université Paris-Saclay,
Palaiseau, Paris,
France
5
Space Sciences Laboratory, University of California,
Berkeley,
CA,
USA
6
International Space Science Institute,
Bern,
Switzerland
7
Department of Engineering Science, University of Oxford,
Parks Road,
Oxford
OX1 3PJ,
UK
★ Corresponding author: matthieu.kretzschmar@cnrs-orleans.fr
Received:
24
March
2025
Accepted:
8
June
2025
Context. In situ studies of the solar wind require precise magnetic field measurements at all frequencies. The Solar Orbiter mission carries two magnetometers to measure the solar wind magnetic field: the fluxgate magnetometer (MAG), which is best suited for frequencies from DC to a few Hertz, and the search coil magnetometer (SCM), which is best suited for frequencies above a few Hertz.
Aims. The aim of this paper is to produce a merged magnetic field data product that takes the best of both instruments and provides the community with high quality, easy to use magnetic field data over a wide range of frequencies.
Methods. We first compared the two instruments in their overlapping frequency range, then we performed the merging in Fourier space using a weighted function determined by the sensitivity of the two sensors.
Results. The two instruments are found to give consistent results in their overlapping frequency range. SCM has a lower gain than MAG by 14% around 1 Hz and MAG is delayed by about 20 ms with respect to SCM, and the merged magnetic field takes care of these discrepancies. It is basically identical to MAG data below 2 Hz and to SCM data above about 15 Hz (with amplitude increased by 14%). We show that the merged magnetic field is suitable to analyse waves and turbulence over a broad frequency range, in particular by confirming that ion cyclotron waves can lower the level of energy at the sub ionic scales. The merged magnetic field is distributed as daily files containing the magnetic field at either 256 or 4096 Hz, and either in the radial-tangential-normal co-ordinates or in the spacecraft reference frame co-ordinates.
Key words: instrumentation: miscellaneous / Sun: heliosphere / solar wind
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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