GOES Flux vs STIX counts

Fig. 1: Scatter plot of STIX counts (4 - 10 keV) versus GOES flux and histogram of STIX counts versus GOES flux. STIX counts are background subtracted and divided by the squared distances between Solar Orbiter and the Sun. 1045 flares with Earth look-angles smaller than 90 degrees were selected.

File:Goes-stix-flux-fit.png

Fig. 2 A profile of the histogram shown in Fig. 1. A cubic function fitted to the profile is also shown.

The GOES flux of a flare is estimated using

flux=10^(p0+p1*x+p2**x^2+p3*x^3),

with x=log10(stix_peak_counts)/r^2

where p0, p1, p2 are the parameters from the curve fit, peak_counts is the STIX QL LC peak counts and r is the distance between the Sun and solar orbiter in units of au. The error of an estimated flux is considered to be the same as the error of the nearest point, as shown in Fig. 2.