# Catalog of Hard X-ray Solar Flares Detected with Mars Odyssey/HEND from the Mars Orbit in 2001-2016

## TL;DR

This paper presents a catalog of powerful solar flares detected by the HEND instrument on Mars Odyssey from 2001 to 2016, providing new data on hard X-ray emissions from the Sun from a unique vantage point.

## Contribution

It introduces a new calibration procedure and compiles a comprehensive catalog of solar flares observed in hard X-ray and gamma-ray bands from Mars orbit.

## Key findings

- Catalog includes 60 powerful solar flares from different solar disk positions.
- Provides detailed time profiles, spectra, and power law characteristics of the flares.
- Demonstrates the potential of HEND data for solar flare studies from a Mars orbit perspective.

## Abstract

The study of nonstationary processes in the Sun is of great interest, and lately, multiwavelength observations and registration of magnetic fields are carried out by means of both ground-based telescopes and several specialized spacecraft (SC) on near-Earth orbits. However the acquisition of the new reliable information on their hard X-ray radiation remains demanded, in particular if the corresponding SC provide additional information, e.g. in regard to the flare observations from the directions other than the Sun-Earth direction. In this article we present a catalog of powerful solar flares registered by the High Energy Neutron Detector (HEND) device designed in the Space Research Institute (IKI) of Russian Academy of Sciences. HEND is mounted onboard the 2001 Mars Odyssey spacecraft. It worked successfully during the flight to Mars and currently operates in the near-Mars orbit. Besides neutrons, the HEND instrument is sensitive to the hard X-ray and gamma radiation. This radiation is registered by two scintillators: the outer one is sensitive to the photons above 40 keV and the inner one to the photons above 200 keV. The catalog was created with the new procedure of the data calibration. For most powerful 60 solar flares on the visible and on the far sides of the Sun (in respect to a terrestrial observer), we provide time profiles of flare radiation, summed over all the channels of X-ray and in some cases of gamma-ray bands as well as the spectra and characteristics of their power law approximation. We briefly discuss the results of the previous articles on the study of the Sun with HEND instrument and the potential of the further use of these data.