Dynamic radio spectrum (bottom) of the LOFAR observation of the Sun on June 23, 2012, showing the normalized flux density in arbitrary units. Time and frequency resolution are given by Δt and Δf. Typical signatures of three type-III bursts are found at 11:00:05, 11:00:11 and 11:01:54 UTC. The vertical features between the second and third burst are broadband radio frequency interference (RFI). The simultaneous X-ray flux from the GOES 15 satellite (top) does not indicate any flare activity.