The geomagnetic field was at quiet to active levels on April 24. A weak solar wind shock was observed at ACE at 06:14 UT. The source is uncertain, with an outside chance that the source was the April 22 CME. Solar wind speed at SOHO ranged between 478 and 599 km/sec, averaging 517 km/sec (-8 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux was at background levels.
Solar flux density measured at 20h UT on 2.8 GHz was 169.6 - increasing 10.2 over the previous solar rotation. The 365 days average solar flux at 1 AU was 194.31 (183 days ago). SC25 peak: 195.86 on October 13, 2024 (subtracting a baseline solar flux level of 65, this is +62.6% compared to the SC24 peak and -1.7% compared to the SC23 peak). The Potsdam WDC planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 13.0). Three hour interval K indices: 33434221 (planetary), 22433322 (Boulder), 42334233 (Andenes).
The background x-ray flux is at the class C1 level (GOES 19).
At the time of counting spots (see image time), spots were observed in 19 active regions using 2K resolution (SN: 399) and in 15 active regions using 1K resolution (SN: 238) SDO/HMI images.
AR 14062 [S03W57] was mostly quiet and stable.
AR 14064 [N10W32] gained area as more new flux emerged in the
intermediate spot section. M flares are possible.
AR 14065 [S32W26] was quiet and stable.
AR 14067 [S03W30] developed early in the day, then decayed again.
AR 14068 [S26E24] decayed slowly and quietly.
AR 14069 [S08W19] decayed slowly and quietly.
AR 14070 [S12E12] matured as longitudinal extension increased. An M
flare is still possible. C1 flares: C1.7 @ 04:16, C1.4 @ 06:22, C1.6 @
16:18, C1.3 @ 18:13 UT
AR 14072 [S18E49] was quiet and stable.
New AR 14073 [N11E39] emerged on April 23 and was numbered by SWPC
the next day.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S10999 [N15E10] was mostly quiet and stable.
S11000 [S20W46] developed slowly and was mostly quiet. C1 flares:
C1.5 @ 06:55, C1.7 @ 15:12 UT
S11009 [S06E35] was quiet and stable.
S11012 [S17W03] was quiet and stable.
S11016 [S09W42] decayed slowly and quietly.
S11017 [N06E71] was quiet and stable.
S11018 [S11E59] developed slowly and quietly.
New region S11020 [S17E73] rotated into view with several spots.
New region S11021 [N18E80] rotated into view with a tiny spot.
New region S11022 [N21E37] was observed with tiny spots in an old
plage area.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.8 | 00:28 | N15W12 | 14064 | GOES19 | |
| C3.2 | 00:39 | 14064 | GOES19 | ||
| C3.0 | 01:44 | 14070 | GOES19 | ||
| C3.0 | 02:37 | 14067 | GOES19 | ||
| C2.4 | 14:34 | 14064 | GOES19 | ||
| C2.4 | 14:44 | 14064 | GOES19 | ||
| C2.0 | 15:41 | 14064 | GOES19 |
April 23-24: No obviously Earth directed CMEs.
April 22: A number of CMEs were observed during the day. The only one
that might have an Earth directed company was observed after a C2.9 flare in
AR 14065 when that region was rotating across the central meridian. While
most of the CME was directed due south, there is a chance of CME effects on
April 25.
[Coronal
hole history (since October 2002)]
[Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago]
A very large positive polarity southern hemisphere coronal hole (CH1286) rotated across the central meridian on April 17-25. A small northern hemisphere positive polarity coronal hole (CH1287) was Earth facing on April 22. Another northern hemisphere positive polarity coronal hole (CH1288) was Earth facing on April 24.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be at quiet to active levels on April 25-28 due to effects from CH1286/CH1288 and effects from the April 22 CME, occasional minor storm intervals are possible.
| Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
1) Effects from a coronal hole could
reach Earth within the next 5 days. When the high speed stream has arrived
the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96
hours.
3) There is a possibility of either M or X class flares within the
next 48 hours.
Green: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution).
4K resolution.
Compare to the previous
day's image. 0.5K image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.
Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers. SWPC data considered to be not sufficiently precise (location, area, classification) are colored red.
| Active region | SWPC date numbered STAR detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC/ USAF |
STAR | SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 14062 | 2025.04.14 2025.04.15 |
3 | 12 | 5 | S03W57 | 0070 | HAX | CAO |
 |
 |
was AR S10984 area: 0150 |
| S10985 | 2025.04.14 | N05W57 | |||||||||
| 14064 | 2025.04.15 2025.04.16 |
12 | 45 | 24 | N11W32 | 0200 | EAI | EAC |
 |
 |
was AR S10989 location: N10W32 area: 0430 |
| 14065 | 2025.04.16 2025.04.17 |
1 | 3 | 1 | S31W27 | 0040 | HSX | CSO |
 |
 |
was AR S10990 location: S32W26 area: 0090 |
| 14066 | 2025.04.17 | 1 | S05W44 | 0010 | AXX | trailing spots of AR 14062. There was no obvious reason for SWPC's split, which would make this an interpretational mistake | |||||
| 14067 | 2025.04.17 2025.04.18 |
1 | 7 | 2 | S03W27 | 0010 | AXX | CRO |
 |
 |
was AR S10994 location: S03W30 area: 0020 |
| S10999 | 2025.04.19 | 18 | 3 | N15E10 | 0030 | BXO |
 |
 |
|||
| S11000 | 2025.04.19 | 11 | 5 | S20W46 | 0040 | CRI |
 |
 |
|||
| 14068 | 2025.04.20 2025.04.21 |
2 | 10 | 4 | S26E22 | 0050 | DSO | CAO |
 |
 |
was AR S11002 location: S26E24 |
| S11003 | 2025.04.20 | S20W47 |
 |
||||||||
| 14070 | 2025.04.20 2025.04.22 |
7 | 37 | 19 | S12E14 | 0090 | DAI | DAI |
 |
 |
was AR S11004 area: 0300 location: S12E12 |
| 14069 | 2025.04.20 2025.04.22 |
5 | 17 | 8 | S09W17 | 0040 | DAO | DAO |
 |
 |
was AR S11006 location: S08W19 area: 0060 |
| S11007 | 2025.04.21 | N10W13 | |||||||||
| S11009 | 2025.04.21 | 2 | S06E35 | 0004 | AXX |
 |
 |
||||
| 14071 | 2025.04.22 | 3 | S13W99 | 0010 | BXO | SWPC probably regarded ARs S10997 and S10998 as one region | |||||
| S11010 | 2025.04.22 | N22W13 |
 |
||||||||
| 14072 | 2025.04.22 2025.04.23 |
1 | 1 | 1 | S18E52 | 0050 | HSX | HSX |
 |
 |
was AR S11011 area: 0130 location: S18E49 |
| S11012 | 2025.04.22 | 4 | 1 | S17W03 | 0010 | AXX |
 |
 |
|||
| S11013 | 2025.04.22 | N22W52 | |||||||||
| S11014 | 2025.04.22 | S33W37 | |||||||||
| 14073 | 2025.04.23 2025.04.24 |
6 | 21 | 8 | N12E40 | 0030 | DRI | DRI |
 |
 |
beta-gamma was AR S11015 location: N11E39 area: 0080 |
| S11016 | 2025.04.23 | 2 | S09W42 | 0002 | BXO |
 |
 |
||||
| S11017 | 2025.04.23 | 1 | 1 | N06E71 | 0250 | HHX |
 |
 |
|||
| S11018 | 2025.04.23 | 5 | 2 | S11E59 | 0012 | CRO |
 |
 |
|||
| S11019 | 2025.04.23 | N34W55 |
 |
||||||||
| S11020 | 2025.04.24 | 10 | 5 | S17E73 | 0040 | DRO |
 |
||||
| S11021 | 2025.04.24 | 1 | N18E80 | 0002 | AXX |
 |
|||||
| S11022 | 2025.04.24 | 2 | N21E37 | 0002 | AXX |
 |
|||||
| Total spot count: | 42 | 209 | 88 | ||||||||
| Sunspot number: | 152 | 399 | 238 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 80 | 269 | 148 | (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10) | |||||||
| Relative sunspot number (Wolf number): | 167 | 219 | 190 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2014.02 | 170.3 (cycle peak) |
166.3 | 146.1 (SC24 peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (SC24 solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (SC24 peak) |
| 2019.11 | 70.2 | 68.7 | 0.5 | 2.0 (-0.6) (Solar minimum using 365d smoothing: November 17, 2019) |
4.19 |
| 2019.12 | 70.8 | 68.6 | 1.6 | 1.8 (-0.2) (ISN 13 months smoothed solar minimum) |
3.22 |
| 2023.10 | 142.8 | 141.9 | 99.9 | 124.8 (+0.8) | 8.16 |
| 2023.11 | 153.5 | 150.2 | 107.1 | 127.9 (+3.1) | 12.20 |
| 2023.12 | 151.1 | 146.4 | 113.5 | 129.5 (+1.6) | 9.60 |
| 2024.01 | 164.6 | 159.3 | 126.0 | 131.2 (+1.7) | 5.46 |
| 2024.02 | 172.5 | 168.3 | 123.0 | 136.9 (+5.7) | 5.31 |
| 2024.03 | 154.4 | 152.9 | 103.7 | 141.4 (+4.5) | 11.03 |
| 2024.04 | 161.3 | 162.6 | 137.0 | 144.5 (+3.1) | 9.69 |
| 2024.05 | 187.7 | 191.9 | 172.1 | 149.1 (+4.6) | 23.56 (SC25 peak) |
| 2024.06 | 184.3 | 190.2 | 164.1 | 152.8 (+3.7) | 10.24 |
| 2024.07 | 196.6 | 203.0 | 196.8 | 155.0 (+2.3) | 7.13 |
| 2024.08 | 246.1 (cycle peak) |
252.2 | 216.0 (SC25 peak) | 156.8 (+1.8) | 15.96 |
| 2024.09 | 195.7 | 197.8 | 141.1 | 159.4 (+1.6) | 15.36 |
| 2024.10 | 221.0 | 219.6 | 165.8 | (160.3 projected, +0.9) | 18.99 |
| 2024.11 | 199.6 | 195.3 | 154.1 | (157.7 projected, -2.6) | 9.33 |
| 2024.12 | 197.3 | 191.2 | 154.6 | (153.9 projected, -3.8) | 8.42 |
| 2025.01 | 190.3 | 184.2 | 137.0 | (148.4 projected, -5.5) | 13.17 |
| 2025.02 | 184.2 | 179.7 | 154.7 | (139.9 projected, -8.5) | 14.42 |
| 2025.03 | 163.7 | 162.1 | 134.2 | (133.5 projected, -6.4) | 15.96 |
| 2025.04 | 164.6 (1) | 98.1 (2A) / 122.7 (2B) / 148.1 (2C) ISN average: 135 |
(128.9 projected, -4.6) | (20.9) | |
| 2025.05 | (123.6 projected, -5.3) | ||||
| 2025.06 | (118.6 projected, -5.0) | ||||
| 2025.07 | (114.5 projected, -4.1) | ||||
| 2025.08 | (109.8 projected, -4.7) | ||||
| 2025.09 | (105.5 projected, -4.3) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value
at 2800 MHz and any corrections applied to that measurement.
2A) Current impact on the monthly sunspot number based on the Boulder
(NOAA/SWPC) sunspot number (accumulated daily sunspots / month days).
2B) Boulder SN current month average to date.
2C) STAR SDO 1K Wolf number 27 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap
indices. Values in red
are based on the definitive international
GFZ Potsdam WDC ap
indices.
4) Source: WDC-SILSO, Royal Observatory
Of Belgium, Brussels
Sunspot activity has been on a slowly decreasing trend since September 2024 (using the average solar flux over 3 solar rotations as a proxy). All 365 days smoothed sunspot numbers peaked on October 11-12, 2024, very likely making this the solar max. SDO1K 365d peak: 236.1, SDO2K 365d peak: 364.4, NOAA SN 365d peak: 156.0, ISN 365d peak: 163.6. The 365d smoothed solar flux peaked on October 13, 2024, only 1.7% below the SC23 peak, and 62.6% above the SC24 peak.
--------------------------------------------------------------------------------------
This report has been prepared by Jan Alvestad. It is based on the analysis of data from whatever sources are available at the time the report is prepared. All time references are to Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
