Fig. 2: Evolution of the observed R_βγ.

The top panel shows a spacetime map of R_βγ in which decreases in the ratio in response to the flare on 23 March 2024 were observed. The large spatial PSF results in ‘ghost images’ of the flare that (although weak in intensity) show up in R_βγ maps as that quantifies the relative response. The bottom panels show the lifetime of the decrease in R_βγ in flare sources from the strong ribbon (bottom left) and weaker ribbon (bottom right). The thin coloured lines represent light curves from different pixels within each source, the thick black line is the weighted mean R_βγ and the red dashed line is a Gaussian fit to the mean. The full-width at half-maximum (FWHM) of the mean light curve is indicated in each plot. The green curves are the Lyβ intensities from pixel 415 (solar − Y ≈ −251.49″) in the strong footpoint and pixel 386 (solar-Y ≈ −283.49″) in the weak footpoint, as functions of time relative to the R_βγ minimum. Error bars for R_βγ result from a standard error propagation of the uncertainties in individual intensities of Lyβ and Lyγ (which themselves account for the combined uncertainty⁵⁴ in intensity from photon shot noise, dark currents and readout noise). Note that a −50″ offset has been applied to SPICE’s solar-Y pointing information.