M4.3-Class Solar Flare Observed at the Bucharest Solar Observatory

Solar activity has increased again, and on April 23, 2026, at 08:30 UTC, an M4.3-class flare occurred in active region AR14422. We observed the flare with the H-alpha instrument at the Bucharest Solar Observatory, and the solar radio SDR spectrograph recorded a series of Type III bursts in the HF-VHF band, from 15 MHz to 65 MHz.

Three other M-class flares were recorded that day, some accompanied by CMEs, and the next day two major X2.5-class flares were recorded, as can be seen in the GOES X-ray flux diagram. The active region was near the western limb, and the associated CMEs were not Earth-directed.

The time-lapse animation consists of frames taken one minute apart, and the total duration of the eruption was about 30 minutes.

The strong Type III radio bursts are generated by electron beams moving at relativistic speeds, approximately 0.1–0.5c, in the magnetic field. This phenomenon occurs slightly later, when the shock waves from the eruption reach the solar corona. The spectrogram is 15 minutes long.

Octavian Blagoi, AIRA Scientific Researcher  https://solar.astro.ro

Published on: Apr 28, 2026