Weekly Bulletin on Solar and Geomagnetic Activity Highlights on 05 - 11.04.2021, Forecast on 12 - 19.04.2021, Carrington Rotation 2242, 2243 (14,23.04; 11,47.05.2021) Earth out of ecliptic (-6.6 - -6.2) deg. (S35 - N25 is zone of geoeffectiveness) THE SUNSPOT-FORMING SOLAR ACTIVITY REMAINED ON VERY LOW LEVEL. THE SUNSPOT OBSERVED 5-6.04 (41 SPOTLESS DAYS AT 2021). ESTIMA- TED, MOST LIKELY WEEKLY AVERAGE VALUE OF THE SUNSPOT NUMBER IN THE INTERNATIONAL SYSTEM (old) FOR PERIOD W=2+5/-2 (Wn=4+7/-4). THERE ARE ONE SMALL SUNSPOT GROUP ON NOTHERN HEMISPHERE HAVE BE- EN OBSERWED. 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 LEVEL. 18 SOLAR FLARE OF X-RAY CLASS "A" AND 6 CORONAL MASS EJECTIONS (8, 10-11.04) WAS OBSERVED. ------------------------------------------------------------------- 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 deg. 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 Sp/craft CH - S05L151 S30L172 S35L146 S30L144 ~2% 05.04 1 - SOHO,SDO... * - 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 11.04/0210 UT THE EARTH IS IN THE "-" SECTOR OF THE INTERPLA- NETARY MAGNETIC FIELD. THE FOLLOWING SECTOR BOUNDARY "-/+" IT CAN BE EXPECT 20.04. ---------------------------------------------------------------------- MARCH 05 06 07 08 09 10 11 áðòåìø Wus 011 011 000 000 000 000 000 F10.7 072 074 076 074 076 078 073 èbcg 2 3.2E+6 1.9å+6 1.6E+6 1.5E+6 1.6E+6 1.4å+6 1.4E+6 GOES Ie>2 398 212 157 132 165 141 136 pfu Ap 3 3 17 3 3 5 6 nô Dst nô KIOTO Amsc 3 3 18 4 2 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 NO OBSERVED. NEXT WEEK THE GREATER THAN 2 MeV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT IS NOT EXPECTED. GEOMAGNETIC CONDITION ALL THE PERIOD REMAINED QUIET AND UNSETTLED EXCEPT 7.04 WHEN ON THE CENTER DATA IN BOULDER WAS OBSERVED 9h G1 -SUBSTORM. ON THE DATA ISMIRAN IT WAS A G1-SUBSTORM WITH A DURATI- ON OF 6h. THE MAGNETIC DISTURBANCE WAS CAUSED BY THE EARTH's PAS- SAGE OF INTERACTING WEAK HIGH-VELOCITY STREAMS FROM A CONGLOMERATE OF SMALL CORONAL HOLES WITH WEAK MAGNETIC FIELDS. IN THE NEXT WEEK THE MOST PROBABLE IS EXPECTED A QUITE AND UNSET- TLED 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