From the SIDC PRESTO alert on 1 February/13:49 UTC: "An X1.0 flare ... was observed in the GOES 19 x-ray flux data with start time 12:25 UTC, peak time 12:33 UTC and end time 12:37 UTC on 1 February. The flare is associated with SIDC Sunspot Group 784 (NOAA Active Region 4366). This is the largest, most complex and currently rather active sunspot group on the visible solar disk. It is classified as magnetic type beta-gamma-delta and has produced multiple M-class flaring over the past hours. No proton event has been associated to the flaring activity up to this moment. Further coronagraph and solar imagery is awaited to estimate any possible related coronal mass ejection (CME). Further M-class flaring related to this region is very likely with chances for more X-class flaring. Increase in the proton flux levels might be expected with a possible proton event over the next 24 hours."
The images (SDO/HMI) underneath show the quick development of NOAA 4366 over the last 40 hours (from 31 January at 00:00 UTC until 1 February near 16:00 UTC). The group has currently a size of 5 times the entire surface area of the Earth, and still growing. The next clip shows the magnetic structure of the group, clearly a mix of sunspots with an opposite magnetic polarity. Red colours represent magnetic field lines coming out of the solar surface ("positive"), blue is for magnetic field lines returning to the solar surface ("negative"). Sunspots with opposite polarities that are close to each other are likely structures to produce strong solar flares.
The clip underneath shows the flaring activity (bright "flashes") over NOAA 4366 but seen in extreme ultraviolet at temperatures of several million degrees (SDO/AIA 131). Several M-class ("medium") flares are preceding and following the main X1.0 event that peaked at 12:33 UTC. The blooming and diffraction patterns that can be seen in these images are instrumental (more information is in Note 1 of this STCE newsitem).
The eruption seems not to have been associated with any solar radiation storm (the flux of energetic protons has remained at background levels). Also, radio astronomy stations such as Humain (SIDC, Belgium) have not detected any obvious radio bursts (Type II) that may be linked to a coronal mass ejection (i.e. the ejection of a magnetic cloud filled with charged particles from the Sun into space). So far, none of the currently available coronagraphic images taken by SOHO or STEREO-A show a CME signature related to today's X-class flare. This may change over the coming days as the region further develops and rotates further to the central portion of the solar disk.
The ionizing radiation of the X-class flare itself affected the lower frequency portion of the High Frequency communication band (HF Com ; 3 - 30 MHz) on the dayside of the Earth, mainly over Africa, the southern portion of the Atlantic Ocean, and most of South-America. An advisory to civil aviation has been issued (PECASUS). The effects of the X1 flare on HF Com can be seen in the D-RAP (NOAA/SWPC) map underneath.
