Weekly Bulletin on Solar and Geomagnetic Activity Highlights on 20 - 26.04.2020, Forecast on 27.04 - 05.05.2020, Carrington Rotations 2229, 2230 (28,37.03; 24,65.04.2020) Earth out of ecliptic (-5.3 - -5.0) deg. (S35 - N20 is zone of geoeffectiveness) THE SUNSPOT-FORMING SOLAR ACTIVITY REMAINED VERY LOW. SPOT- LESS VISIBLE DISK HAVE BEEN OBSERVED BEFORE 25.04 (90 SPOT- LESS DAYS IN THE 2020). ESTIMATED, MOST LIKELY WEEKLY AVERA- GE VALUE OF THE RELATIVE SUNSPOT NUMBER IN THE INTERNATIONAL SYSTEM (old) FOR PERIOD W = 2.1+6/-2.1 (Wn=3.6+11/-3.6). ONE SOLAR SUNSPOT GROUP OF CURRENT SOLAR CYCLE WAS APPEARED ON VI- SIBLE SOLAR DISC AT 25.04. NEXT WEEK THE LEVEL OF SUNSPOT ACTIVITY WAS ON VERY LOW LEVEL. LIKELY WEEKLY AVERAGE VALUE OF THE RELATIVE SUNSPOT NUMBER IN THE INTERNATIONAL SYSTEM (old) FOR NEXT WEEK IS W=010+10/-10. FLARE ACTIVITY WAS AT THE VERY LOW LEVEL, BUT 7 SOLAR FLARE OF A CLASSES (23, 26.04) AND ONE CORONAL MASS EJECTIONS (23.04) WAS OBSERVED OF 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 DSF to te localization l × ÇÒÁÄ. Fl AR CME/to -------------------------------------------------------------------- NEXT WEEK THE FLARE ACTIVITY IS EXPECTED AT 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 Spacecraft CH* + N10L355 S05L017 S15L007 N07L315 10.8% 27/04 R1 SDO,SOHO... * - 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 12.03/20 UT THE IMF SECTOR SIGN WAS "-". NEXT WEEK THE BEHAVIOR OF THE SECTOR STRUCTURE SIGN WILL NOT CHANGE. THE REAL PROVISION OF THE NEXT SECTOR BOUNDARY IS NOT IMPOSSIBLE, MAY BE BECAUSE OF THE CON- DITIONS OF A DEEP MINIMUM (TOPIC FOR STUDY!!!). ----------------------------------------------------------------------- APRIL 20 21 22 23 24 25 26 APRIL Wus 000 000 000 000 000 011 014 F10.7 068 069 071 069 071 069 069 èbcg >A1.0 2 1.5E+6 1.2å+6 2.9E+6 9.1E+6 5.4E+6 2.7E+6 3.2å+6 GOES Ie>2 195 190 217 342 194 211 225 pfu Ap 18 9 8 4 8 5 6 nô Dst nô KIOTO Amsc 13 10 6 4 6 5 6 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 ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT NOT OBSERVED. NEXT WEEK THE GREATER THAN 2 MeV ELECTRON FLUX AT GEOSYNCHRONOUS OR- BIT IS NOT EXPECTED. THE GEOMAGNETIC CONDITION CHANGED FROM ACTIVE TO QUITE. 20.04 ACCOR- DING TO THE CENTER IN BOULDER TO OBSERVE SUBSTORM G1 INTENSITY AND DURATION 9 HOURS. ACCORDING IZMIRAN DATA IT WAS 6 h. SUBSTORM G0 IN- TENSITY. SOURCE OF DISTURBANCE HAS COME SLOWLY CME FROM SOLAR FILA- MENT EJECTION 15.04. NEXT WEEK THE MOST PROBABLY QUIET AND UNSETTLED GEOMAGNETIC CONDI- TION WILL OBSERVED. 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