Weekly Bulletin on Solar and Geomagnetic Activity Highlights on 17 - 23.05.2021, Forecast on 24 - 30.05.2021, Carrington Rotation 2244 (7.69.06.2021) Earth out of ecliptic (-3.5 - -3.1) deg. (S38 - N30 is zone of geoeffectiveness) THE SUNSPOT-FORMING SOLAR ACTIVITY REMAINED ON LOW LEVEL. ES- TIMATED, MOST LIKELY WEEKLY AVERAGE VALUE OF THE SUNSPOT NUM- BER IN THE INTERNATIONAL SYSTEM (old) FOR PERIOD W= 12+6/-4 (Wn=19+11/-6). TWO SMALL SUNSPOT GROUP WAS OBSERVED ON THE SO- LAR VISIBLE DISK. NEXT WEEK SUNSPOT ACTIVITY WILL BE ON VERY LOW LEVEL. WEEKLY AVERAGE VALUE OF THE RELATIVE SUNSPOT NUMBER IN THE INTERNATI- ONAL SYSTEM (old) FOR NEXT WEEK IS W=020+10/-10. FLARE ACTIVITY WAS AT LOW LEVELS. THREE SOLAR FLARE OF X-RAY "M" CLASS, 16 - "C", 67 - "B" AND 13 CORONAL MASS EJECTIONS (18, 19, 21, 22, 23.05) WAS OBSERVED AT THE PERIOD. ------------------------------------------------------------------- FLARES >M1 X-RAY CLASSES to tm te local. Class E(1-8A) AR RII/IV CME X-ray/Ïp J/m-2 22.05 1703 1716 1711 N18E18L194 M1.1/1N 4.3E-03 12824 22.05 2130 2136 2143 N19E15L194 M1.4/1N 7.1E-03 12824 22/2212 23.05 1100 1114 1108 N20E05L194 2N/M1.1 5.3E-03 12824 DSF to te localization l deg. Fl AR CME/to 21.05 >0033 >1250 S50E35L260 38 22.05 >1527 >1334 N32W08L205 24 -------------------------------------------------------------------- NEXT WEEK THE FLARE ACTIVITY IS EXPECTED AT LOW AND VERY LOW LEVEL. ON THE VISIBLE SOLAR DISK THE FOLLOWING CORONAL HOLES WERE OBSERVED: --------------------------------------------------------------------- sign N end E end S end W end Sch EE R G Sp/craft * - low geoeffectivity, the substorms with duration <6 h. only. Sch - CH area in % solar hemisphere near the central meridian on https://www.solarmonitor.org/; n/d - no data; R - solar rotations; EE-date of possible geomagnetic disturbance in the Earth's environment. G(0-5)-geoeffectivity in last solar rotation on the middle latitudes. A-active geomagnetic condition. ---------------------------------------------------------------------- AFTER 12.05/0750 UT THE EARTH IS IN THE "-" SECTOR OF THE INTERPLA- NETARY MAGNETIC FIELD. THE FOLLOWING SECTOR BOUNDARY "-/+" IT CAN BE EXPECT 27.05. ---------------------------------------------------------------------- MAY 17 18 19 20 21 22 23 íáê Wus 011 024 024 013 013 019 030 F10.7 075 076 076 072 074 076 079 èbcg á7.3 á7.6 á6.7 á5.8 á7.1 ÷1.8 B1.4 GOES Sp 040 160 170 150 150 190 200 msh N 1 1 IMF - - - - - - - DSCOVR Å>2 2.4å+6 1.7E+6 2.2å+8 1.5E+6 2.7E+7 3.9E+7 3.8å+7 GOES Ie>2 414 177 154 117 819 1035 794 pfu Ap 6 10 6 24 7 5 4 nô Dst nô KIOTO Amsc 7 10 6 27 8 5 4 nô IZMIRAN ---------------------------------------------------------------------- Å>2 - Daily Electron Fluency e/(cm2-ster-day) with E>2 MeV. Ie>2 - the maximum intensity of electron flux in geostationary or- bits in days according to GOES-15 in (electrons/cm2.s.sr) for events > 1000 pfu. THE GREATER THAN 2 MeV RECURRENT ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT WAS OBSERVED 22.05 ONLY. NEXT WEEK THE GREATER THAN 2 MeV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT IS NOT EXPECTED. MINOR MAGNETIC STORM (G1, Ams=32, dur.=15 h) ACCORDING TO THE CEN- TER IN BOULDER DATA AND (G1, Ams= 43, dur.= 12 h) ACCORDING TO IZMIRAN DATA WAS OBSERVED ON 20.05 AS A CONSEQUENCE DISTURBANCES FROM SOLAR FILAMENT EJECTION IN THE CENTRAL ZONE OF THE VISIBLE SOLAR DISC. OTHER DAYS THE GEOMAGNETIC CONDITION REMAINED QUIET AND UNSETTLED. IN THE NEXT WEEK 26.05 A GROWTH OF GEOMAGNETIC DISTURBANCE IS POS- SIBLE BECAUSE OF THE SPLASH OF FLARE ACTIVITY 22.05. PROBABILITY OF A MAGNETIC STORM NOT MORE THAN 20%. IN OTHER DAYS THE MOST PRO- BABLE IS EXPECTED A QUITE AND UNSETTLED GEOMAGNETIC CONDITION. HIGHLIGHT AND FORECAST COMPOSED FROM DATA: NOAA SWPC, BOULDER, USA http://www.swpc.noaa.gov, THE SOLAR INFLUENCES DATA ANALYSIS CENTRE, SIDC, BRUSSELS, BELGIUM http://sidc.oma.be/index.php3, THE IZMIRAN, MOSCOW, TROITSK, RUSSIA http://www.izmiran.ru V. Ishkov