Cross-Calibration of SMART-1 XSM with GOES and RHESSI

TL;DR

This study compares X-ray observations from SMART-1 XSM with GOES and RHESSI instruments, providing flux calibration and analyzing differences in temperature, emission measures, and flux ratios to improve cross-calibration accuracy.

Contribution

It presents the first detailed cross-calibration of XSM with GOES and RHESSI, including flux calibration and comparison of physical parameters.

Findings

XSM and GOES fluxes agree within 6%

XSM observes higher temperatures and emission measures than GOES

XSM fluxes are about 2.6 times higher than RHESSI fluxes

Abstract

A number of X-ray instruments have been active in observing the solar coronal X-ray radiation this decade. We have compared XSM observations with simultaneous GOES and RHESSI observations. We present flux calibrations for all instruments, and compare XSM and GOES total emission measures (TEM) and temperatures (T). The model-independent flux comparison with XSM and GOES data at the 1 - 8 angstrom band shows that the fluxes agree with a ratio of 0.94 +/- 0.09 for the data up to April 2005. The Mewe model-dependent Ts and TEMs differ as XSM observes 1.47 +/- 0.03 times higher Ts than GOES and 1.23 +/- 0.08 times higher TEMs and 0.92 +/- 0.05 times lower fluxes. The comparison with RHESSI data at the 6 - 8 keV band shows that the average XSM/RHESSI flux ratio is 2.63 +/- 0.23. The discrepancies revealed in this study were similar to discrepancies observed in a number of other spaceborne cross-calibration studies.