It was found that there are obvious artefacts in HMI observables in the WLF transients due to the time-lag in sampling of the spectral line by HMI, which led to an apparent change of the shape of the spectral line and thus false values of Doppler velocity. The authors point out that similar effects may be expected in the derived intensity of the line-of-sight magnetic field.

Thus we took and opportunity and searched for $I_{\rm c}$ emission causally connected to a set of solar flares. For the purpose of this work, we initially focused to strong flares only that were classified as M5.0 or stronger, thus with an X-ray 0.1–0.8 nm flux of $5\times10^{-5}$ Wm$^{-2}$ or larger. The lower limit is a technical one, white-light emission was observed for flares as weak as C-class [e.g. @2006SoPh..234...79H], and we propose to extend our work towards weaker flares in the future. In order to avoid possible problems with projection effects, we further limited our sample to flares that ignited not farther than 50 heliographic degrees from the disc centre. Those WLF candidates were searched for in the archive of events detected by GOES satellites, the first one considered was a M6.6-class flare 