Radiation Moniter (RDM)


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.NameUnitFormat
1DateYYYYMMDDi8date of observation
2TimeHHMMSS (UT)1x,i6start time of each 16-s period
3Lf7.2L value with the model geomagnetic field with the IGRF 2005
4INVdeg.f6.2invariant latitude
5FMLATdeg.f7.2magnetic latitude of the S/C footpoint
6MLATdeg.f7.2magnetic latitude
7MLThoursf6.2magnetic local time
9GLATdeg.f7.2geographic latitude
10GLONdeg.f7.2geographic longitude
11FEIO1/(cm2 s sr)e11.3electron 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."


Prof. Tsugunobu Nagai
Tokyo Institute of Technology
2-12-1 Ookayama, Meguro, Tokyo 152-8551
E-mail: nagai AT geo.titech.ac.jp


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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Last Modified: 05 January 2021