25 CYCLE OF SOLAR ACTIVITY, THE BRANCH OF RISE: THE PHASE OF MINIMUM Weekly Bulletin on Solar and Geomagnetic Activity Highlights on 11 - 17.10.2021, Forecast on 18 - 25.10.2021 Carrington Rotations 2249, 2250 (24,59.09; 21,88.10.2021) Earth out of ecliptic (-0.6 - -1.4) deg. (S30 - N30 is zone of geoeffectiveness) THE SUNSPOT-FORMING SOLAR ACTIVITY WAS ON LOW AND VERY LOW LEVELS. AFTER 17.10 TYE SUN WAS SPOTLESS (2021 total:60 days- 21%). ESTIMATED MOST LIKELY WEEKLY AVERAGE VALUE OF THE SUN- SPOT NUMBER IN THE INTERNATIONAL SYSTEM (old) FOR PERIOD IS W= 12+9/-12 (Wn=19+16/-19). THERE WERE THREE SMALL INACTIVE SUN- SPOT GROUPS ON VISIBLE SOLAR DISK, ALL - ON N-HEMISPHERES)HAS BEEN OBSERVED. NEXT WEEK SUNSPOT ACTIVITY WILL BE ON VERY LOW AND LOW LEVELS. WEEKLY AVERAGE VALUE OF THE RELATIVE SUNSPOT NUMBER IN THE IN- TERNATIONAL SYSTEM (old) FOR NEXT WEEK IS W=020+20/-20. FLARE ACTIVITY WAS AT MIDDLE AND LOW LEVELS. 5 FLARES OF X- RAY CLASS "C", 56 - CLASS "B", TWO SOLAR FILAMENT EJECTIONS AND 13 CORONAL MASS EJECTIONS (11-16.10) HAVE BEEN 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 (EPL) to te localization l deg. Fl AR CME/to 12.10 0146 0203 N23W28L158 6 B9.5 12882 CME/0324 15.10 1509 1559 N15w90L170 ~10 B9.7 12885 CME/1600 -------------------------------------------------------------------- NEXT WEEK THE FLARE ACTIVITY IS EXPECTED AT VERY LOW AND LOW LEVELS. 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 + N40L080 N35L085 N22L062 N32L057 1.7% 19.10 1 - SDO,SOHO,ACE CH - S10L051 S35L066 S45L056 S25L021 1.1 20.10 2 A SDO,SOHO,ACE * - 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. ---------------------------------------------------------------------- 16.10/09 UT THE EARTH IS IN THE "+" SECTOR OF THE INTERPLANETARY MAG- NETIC FIELD. FOLLOWING SECTOR BOUNDARY "+/-" IT CAN BE EXPECT 21.10. ----------------------------------------------------------------------- OCTOBER 11 12 13 14 15 16 17 OCTOBER Wus 035 026 027 024 011 011 000 F10.7 089 084 084 083 084 078 077 èbcg B1.0 á8.9 A7.4 á7.1 A5.3 A5.9 A4.9 GOES Sp 270 280 270 260 250 120 000 msh N 1 IMF ~ +/- - - - -/+ + DSCOVR Å>2 2.6E+6 2.7E+6 1.4E+6 3.7E+6 9.4å+6 1.2E+7 3.6E+6 GOES Ie>2 273 322 193 284 430 671 251 pfu Ap 13 45 6 6 5 5 10 nô Dst -24 -53 -33 -23 nô KIOTO Amsc 12 34 5 8 4 5 13 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. Pr>10 MeV: To=09/~14; max 09/~20 - 1.31pfu; Te=12/~02 UT. THE GREATER THAN 2 MeV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT NOT OBSERVED. NEXT WEEK THE GREATER THAN 2 MeV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT IS CAN EXPECTED 20 - 25.10. A MINOR MAGNETIC STORM (G2, Ams=49, dur.=18 h) ACCORDING TO THE CENTER IN BOULDER DATA AND (G1, Ams= 33, dur.= 27 h) ACCORDING TO THE IZMIRAN DATA, 11-12.10 BECAMT THE RESULT OF THE COMING OF DIS- TURBATION FROM FLARE EVENT OF CLASS M1.6/1N 09.10. ON OTHER DAYS THE GEOMAGNETIC CONDITION WERE QUIET AND UNSETTLED . THE NEXT WEEK 19-20.10 IS PROBABLE TO EXPECT A MAGNETIC STORM DUE TO THE EARTH PASSAGE HIGH SPEED STREAMS FROM CORONAL HOLES (CH-Tab- le) AND ARRIVAL OF THE DISTURBATION FROM THE SOLAR FLARE B9.7 WITH SOLAR FILAMENT EJECTION AND CME 15.10. IN OTHER DAYS MOST PROBABLE QUIET 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