Radiation Moniter (RDM)
Data
The radiation monitor (RDM) on Akebono has been observing electron fluxes in three energy ranges (0.3-0.95, 0.95-2.5, >2.5 MeV) [Takagi et al., 1993]. RDM is not designed to be a scientific instrument so that its capability is very limited. The sensor view is perpendicular to the Sun-pointing spin axis, and the spin period is 8 s. The sensor has a wide view angle. Although basic time resolution for particle measurements is 0.5 s, 16 s averaged data have enough counts to be statistically meaningful. Isotropic flux distributions should be assumed, and no pitch angle information is available. Only real-time data are received at two ground stations in Japan and Sweden now, and data coverage is approximately 20%. On 1 March 2014, the orbit has its apogee at an altitude of 4,230 km and its perigee at an altitude of 280 km. The recent observations are summarized in Nagai [2012].
The data from the >2.5 MeV electron channel are open to the public since noise levels become high in the 0.3-0.95 and 0.95-2.5 MeV electron channels. All the files from 2012 are available, here.
Data Format
| Column No. | Name | Unit | Format | |
|---|---|---|---|---|
| 1 | Date | YYYYMMDD | i8 | date of observation |
| 2 | Time | HHMMSS (UT) | 1x,i6 | start time of each 16-s period |
| 3 | L | f7.2 | L value with the model geomagnetic field with the IGRF 2005 | |
| 4 | INV | deg. | f6.2 | invariant latitude |
| 5 | FMLAT | deg. | f7.2 | magnetic latitude of the S/C footpoint |
| 6 | MLAT | deg. | f7.2 | magnetic latitude |
| 7 | MLT | hours | f6.2 | magnetic local time |
| 8 | ALT | km | f9.2 | altitude |
| 9 | GLAT | deg. | f7.2 | geographic latitude |
| 10 | GLON | deg. | f7.2 | geographic longitude |
| 11 | FEIO | 1/(cm2 s sr) | e11.3 | electron integral energy flux (> 2.5MeV) |
TDAS load procedure
Here, you can find a TDAS load procedure file for RDM data. RDM data analysis becomes available on TDAS with this load procedure. TDAS (THEMIS Data Analysis Software suite) has been developed by THEMIS project. See TDAS web page for details.
Data Policy and Credits
Data are free for scientific publications. If you have any questions or requests about the RDM data, please contact Prof. T. Nagai (Tokyo Institute of Technology). When you publish a paper, please inform Prof. Nagai of your publication. In any publications, the use of the Akebono/RDM data should be acknowledged, for example, as "The Akebono/RDM data were provided through DARTS at Institute of Space and Astronautical Science, JAXA."
Contact
- Prof. Tsugunobu Nagai
- Tokyo Institute of Technology
2-12-1 Ookayama, Meguro, Tokyo 152-8551
E-mail: nagai AT geo.titech.ac.jp
References
- Nagai, T., Rebuilding process of the outer electron radiation belt: The spacecraft Akebono observations, in Dynamics of the Earth's Radiation Belts and Inner Magnetosphere, Geophys. Monogr. Ser., vol 199, edited by D. Summers, I. R. Mann, D. N. Baker, and M. Schulz, pp.177-187, doi:10.1029/2012GM001281, AGU, Washington, D.C., 2012.
- Takagi, S., T. Nakamura, T. Kohno, N. Shiono, and F. Makino, Observations of space radiation environment with EXOS-D, IEEE Trans. Nucl. Sci., 40, 1491-1497, doi:10.1109/23.273513, 1993.
- Tsuruda, K., and H. Oya, Introduction to the EXOS-D (Akebono) Project, Geophys. Res. Lett., 18(2), 293-295, doi:10.1029/91GL00039, 1991.
Mapping Plot
Average electron distribution map plot (Format: GIF)
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Flux Plot
Daily electron flux versus L-value plot (Format: GIF)
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Daily average electron flux plot (Format: GIF)
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(*) Please note that there are large noises caused by sun for Dec. 2007.
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