PROBLEMS OF GEOCOSMOS

Proceedings of the 7th International Conference "Problems of Geocosmos" (St. Petersburg, Russia, 26-30 May 2008)
SUB-RELATIVISTIC ELECTRON PRECIPITATION AT HIGH
LATITUDES: LOW-ALTITUDE SATELLITES OBSERVATIONS
I.N. Myagkova, E.E. Antonova, S.N. Kuznetsov , Yu.I. Denisov,
B. V. Marjin, M.O. Riazantseva
Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119191, Moscow, Russia,
e-mail: irina@srd.sinp.msu.ru
Introduction.
Abstract. The precipitation of electrons with the energies more than 300 keV to the pole of
external radiation belt is studied. Results of observations of CORONAS-F satellite are used.
Low altitude (350-500 km) CORONAS-F satellite was launched into a circular orbit with an
inclination of ~82.5 o and with an initial altitude of about 500 km on July 31, 2001. It operated
until December 12, 2005 with a final altitude of about 350 km. Its orbital period (� 1.5 hours)
corresponds to about 15 circuits per day. Charged particles in different energy ranges (protons
with energy 1-90 MeV, electrons 0.3-12 MeV) were measured by semiconductor and plastic
scintillator telescopes. Localized electron precipitations were observed to the pole from the
external boundary of the external radiation belt. It is shown, that such kind of precipitations can
be observed for about a half of polar crossings. The most of them were observed during
southward Bz component of interplanetary magnetic field. Results of observations are compared
with data of auroral satellite Meteor-3M. The nature of observed phenomena is discussed.
Outer radiation belt is carefully analyzed from the moment of its discovery. However, the
processes of acceleration of relativistic electrons forming the outer radiation belt are not proper studied till
now. Outer radiation belt is filled as a rule by large particle fluxes during recovery phases of magnetic
storms. The dynamics of such filling and article losses is greatly variable. Radial distribution of the main
peaks of relativistic electrons is comparatively well known (Kuznetsov and Tverskaya, 2007). At the same
time, small-scale features of such distribution are not studied well. In this paper we present the results of
the preliminary simultaneous analysis of observations of relativistic electrons on CORONAS-F satellite and
plasma sheet particles on Meteor-3M satellite and try to show that an additional comparably stable peak of
relativistic electron precipitation can appear at auroral oval latitudes. We also discuss the possible
explanations of the observed phenomena.
Experiments.
CORONAS-F
Russian solar space observatory CORONAS-F was launched into a circular orbit with an inclination
of ~82.5 o and with an initial altitude of about 500 km on July 31, 2001. It operated until December 12, 2005
with a final altitude of about 350 km. Its orbital period equal � 1.5 hours corresponds to about 15 circuits
per day. Charged particles in different energy ranges (protons with energy 1-90 MeV, electrons 0.3-12
MeV) were measured by semiconductor and plastic scintillator telescopes. The devices were developed by
the Skobeltsyn Institute of Nuclear Physics, Moscow State University (Kuznetsov et al., 2002). Due to the
low circular polar orbit of the CORONAS-F satellite fluxes of solar protons and electrons were measured by
the MKL-device on board CORONAS-F experiment only in the south and north polar caps (areas of open
magnetic field lines) during 15-20 minute intervals every ~45 minutes.
Meteor-3M
The satellite Meteor-3M was launched on December 10, 2001 into the orbit with altitude ~ 1000 km
and inclination ~ 99,6�. Its time of circulation was ~105 min (Marjin et al., 2004). The scientific
information was collected from Febriary 19, 2002 till June 12, 2005. Presented data were obtained with the
help of the device MSGI-5EI. MSGI-5EI measures the fluxes of protons and electrons with energies 0.1-10
keV in 50 energy channels and the integral flux of electrons with energies >40 keV. Comparison of
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