------------------------------------------------------------------- THE RELATIVE MONTHLY MEAN SUNSPOT NUMBER ON APRIL 2021 HAS MADE Wmar. = 14.7 24.5(n-in new system) THAT GIVES FOR 10 MONTH (2020, OCTOBER) OF DEVELOPMENT CURRENT 25 SOLAR CYCLE THE SMOOTHED MONTHLY MEAN SUNSPOT NUMBER W*oct. = 7.1 11.9 - × ÎÏ×ÏÊ ÓÉÓÔÅÍÅ W*sep. = 6.2 10.3 - × ÎÏ×ÏÊ ÓÉÓÔÅÍÅ On July 1, 2015 Centre in Brussels moved to a new system of calcu- lation the relative number of sunspots and practically all of the values were replaced throughout the numbered series of Wolf numbers (see link). While there is addictive, I recalculated (0.6) to the old system, but only W*, and present below the new values for the minimum and maximum of 25 cycles SA. THE BEGINNING OF 25 SOLAR CYCLE - I 2020 with W*=1.3; (1.8n) MAXIMUM OF THE CURRENT 25 CYCLE - VI 2024 - Wmax =90-100; (150n) THE END OF 25 SOLAR CYCLE (THE POINT OF MINIMUM) - I - VI 2031; Provisional daily International Sunspot Numbers for April 2021 (70 observatories): 1.. 0 6.. 6 11.. 10 16.. 35 21.. 46 26.. 50 2.. 0 7.. 0 12.. 14 17.. 15 22.. 44 27.. 55 3.. 4 8.. 0 13.. 19 18.. 19 23.. 36 28.. 46 4.. 13 9.. 0 14.. 21 19.. 36 24.. 54 29.. 37 5.. 10 10.. 0 15.. 25 20.. 57M 25.. 55 30.. 29 Minimum : 0 on 1, 2, 7, 8, 9, 10 [The daily value W in old system close to true (in a minimum phase) can be received, multiplying by k = 0.6]. THE MONTHLY MEAN OF OBSERVED RADIO FLUX OF THE 10 cm (2800 MHz) ON APRIL 2021, AND SMOOTHES ON 2020, OCTOBER F10.7apr. = 74.5 F*10.7oct.= 75.2 THE MONTHLY MEAN OF GEOMAGNETIC Ap-index ON APRIL 2021, AND SMOOTHES ON 2021, OCTOBER 2020 Ap apr.= 8.6 Ap*oct. = xxx --------------------------------------------------------------------- Weekly Bulletin on Solar and Geomagnetic Activity Highlights on 03 - 09.05.2021, Forecast on 10 - 16.05.2021, Carrington Rotation 2243, 2244 (11,47.05; 7.69.06.2021) Earth out of ecliptic (-4.5 - -4.1) deg. (S30 - N30 is zone of geoeffectiveness) THE SUNSPOT-FORMING SOLAR ACTIVITY REMAINED ON VERY LOW LEVEL AND BEFORE 07.05 THE SUN WAS SPOTLESS (46 DAYS AT 2021). ESTI- MATED, MOST LIKELY WEEKLY AVERAGE VALUE OF THE SUNSPOT NUMBER IN THE INTERNATIONAL SYSTEM (old) FOR PERIOD W= 4+7/-4 (Wn= 7+ 11/-7). ONE SMALL SUNSPOT GROUP WAS OBSERVED ON THE SOLAR VI- SIBLE 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=010+20/-10. FLARE ACTIVITY WAS AT LOW LEVELS. ONE SOLAR FLARE "M" OF X-RAY CLASS, 5-CLASS "C", 32 - "B" AND 9 CORONAL MASS EJECTIONS (3-08. 05) 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 07.05 1843 1904 1919 N17E78L335 M3.9/1N 4.5å-2 12822 II/IV óíå 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 * - 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 29.04/1325 UT THE EARTH IS IN THE "-" SECTOR OF THE INTERPLA- NETARY MAGNETIC FIELD. THE FOLLOWING SECTOR BOUNDARY "-/+" IT CAN BE EXPECT 8.05. ---------------------------------------------------------------------- MAY 03 04 05 06 07 08 09 MAY Wus 000 000 000 000 015 017 018 F10.7 072 070 070 071 075 076 076 èbcg á2.1 á2.9 á2.8 á3.6 á5.0 á6.0 A5.5 GOES Sp 000 000 000 000 130 180 180 msh N 1 IMF + + + + + + + DSCOVR Å>2 1.8E+6 3.3å+8 4.0E+6 4.6E+7 4.9E+7 6.6å+6 5.9E+6 GOES Ie>2 231 239 264 264 282 303 389 pfu Ap 5 4 2 4 3 3 4 nô Dst nô KIOTO Amsc 5 5 3 4 3 4 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 NO OBSERVED. NEXT WEEK THE GREATER THAN 2 MeV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT IS NOT EXPECTED. GEOMAGNETIC CONDITION REMAIND QUITE. 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