The Gamma-Ray Background Model for Detectors Onboard Low-Altitude and High-Inclination Satellites in the Energy Band up to Several MeV

Abstract

Results are presented from an analysis of the temporal behavior of the background count rate in an energy band of up to several MeV for the γ-ray detectors onboard low-altitude satellites, using data of the AVS-F instrument as an example. The instrument was installed onboard the CORONAS-F satellite with orbital parameters of an altitude of ~500 km and an inclination of 82.5°. The temporal profiles of the background count rate in the equatorial orbit regions are approximated by fourth- or fifth-degree polynomials. The applicability of the approximating polynomials is shown for the instruments installed onboard satellites with orbital inclinations of up to 38°, allowing for the evolution of the Kp index in the preceding time interval of 12–24 h before passing the geomagnetic equator. In modeling the RHESSI data of October 27, 2003, at an initial orbital altitude of ~600 km and an inclination of 38°, a mean count rate value of 1017 ± 8 s⁻¹ is obtained in the geomagnetic latitude interval ±5° in the energy range Е > 0.1 MeV (analysis of the data yields a value of 1094 ± 153 s⁻¹).