The geomagnetic field was at quiet to unsettled levels on July 28. Solar wind speed at SOHO ranged between 366 and 502 km/sec, averaging 402 km/sec (-64 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 all day.
Solar flux density measured at 20h UT on 2.8 GHz was 144.6 - increasing 18.8 over the previous solar rotation. The 365 day average solar flux at 1 AU was 180.89 (183 days ago). The 81 day average solar flux at 1 AU was 136.4 (41 days ago, this is 42.6% of the total SC25 solar flux range from the max 81 day average peak on September 4, 2024 at 227.3 and an average 81 day flux of 69 at solar minimum). SC25 365d peak: 195.86 on October 13, 2024. The Potsdam WDC planetary A index was 6 (STAR Ap - based on the average of three hour interval ap indices: 6.0). Three hour interval K indices: 11111223 (planetary), 11123423 (Boulder), 10013343 (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 17 active regions using 2K resolution (SN: 304) and in 14 active regions using 1K resolution (SN: 201) SDO/HMI images.
AR 14149 [N16W53] decayed slowly and quietly.
AR 14150 [S13W53] was quiet and stable.
AR 14152 [N09W31] was quiet and stable.
AR 14153 [S29W21] decayed slowly and was mostly quiet. C1 flares:
C1.5 @ 03:21, C1.8 @ 04:10, C1.9 @ 05:10 UT
AR 14154 [S14W08] was mostly quiet and stable. C1 flares: C1.1 @
07:50, C1.1 @ 09:12, C1.1 @ 15:49, C1.2 @ 17:52 UT
AR 14155 [S08E07] decayed early in the day, then gained tiny spots
after noon and was quiet.
AR 14156 [N11E08] decayed slowly and quietly.
AR 14157 [S20E01] was quiet and stable.
AR 14161 [S12E64] produced a few low level C flares. C1 flares: C1.6
@ 04:06, C1.4 @ 12:53, C1.2 @ 23:56 UT
New AR 14162 [N18W11] emerged on July 27 and decayed on July 28 when
it was numbered by SWPC.
New AR 14163 [N24W08] emerged on July 27 and entered the decay phase
the next day as it was assigned its NOAA number.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S11276 [N09W18] reemerged with tiny spots.
S11277 [S04W20] reemerged with tiny spots.
S11289 [S21E52] was quiet and stable.
New AR S11295 [N17W67] emerged with several spots. C1 flares: C1.1 @
23:17 UT
New AR S11296 [S20W49] was split off from AR 14150 as new flux
emerged.
New AR S11297 [N01E19] was observed with tiny spots in an old
plage area.
A C1.1 flare was recorded at 11:19 UT from a location behind the southwest limb. A C1.1 flare was recorded at 12:33 UT from a location behind the northeast limb, a C1.3 flare was recorded at 21:22 from the same location.
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
July 26-28: No obviously Earth directed CMEs.
[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 negative polarity northern hemisphere coronal hole (CH1308) rotate across the central meridian on July 26-27, however, CH1308 may be too far to the north to cause any geomagnetic disturbance.
The geomagnetic field is expected to be at mostly quiet levels on July 29 - August 1. Some unsettled and active intervals are possible on July 29-30 due to effects from CH1308.
| 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 | ||||||||||
| 14150 | 2025.07.18 2025.07.19 |
1 | 2 | 1 | S14W56 | 0040 | HSX | HSX |
 |
 |
was AR S11267 location: S13W53 area: 0110 |
| 14149 | 2025.07.18 2025.07.19 |
3 | 8 | 2 | N16W51 | 0080 | CSO | CAO |
 |
 |
was AR S11268 location: N16W53 area: 0200 |
| S11270 | 2025.07.19 | S20W47 | |||||||||
| 14152 | 2025.07.20 2025.07.21 |
6 | 3 | N09W38 | 0013 | BXO |
 |
 |
was AR S11275 location: N09W31 |
||
| S11276 | 2025.07.21 | N08W17 | |||||||||
| S11277 | 2025.07.21 | S02W19 | |||||||||
| 14153 | 2025.07.22 2025.07.22 |
5 | 15 | 9 | S29W21 | 0130 | ESO | ESO |
 |
 |
was AR S11278 area: 0290 |
| 14154 | 2025.07.22 2025.07.23 |
3 | 14 | 6 | S14W10 | 0030 | CSO | CSO |
 |
 |
was AR S11279 area: 0120 location: S14W08 |
| 14157 | 2025.07.22 2025.07.24 |
1 | 13 | 5 | S19W00 | 0030 | HSX | CSO |
 |
 |
was AR S11280 area: 0080 location: S20E01 |
| 14155 | 2025.07.23 2025.07.24 |
8 | 37 | 16 | S09E04 | 0020 | CRI | DRI |
 |
 |
was AR S11282 location: S08E07 area: 0070 |
| 14156 | 2025.07.23 | 4 | 1 | N12E04 | 0007 | BXO |
 |
 |
was AR S11283 location: N11E08 |
||
| S11284 | 2025.07.23 | S13W37 | |||||||||
| 14159 | 2025.07.24 2025.07.26 |
S08W39 |
 |
was AR S11285 location: S06W22 |
|||||||
| 14160 | 2025.07.24 2025.07.26 |
1 | S08E19 | 0008 | AXX |
 |
was AR S11286 location: S08E22 spotless |
||||
| S11288 | 2025.07.25 | N20W30 | |||||||||
| S11289 | 2025.07.26 | 3 | 1 | S21E52 | 0010 | CRO |
 |
 |
|||
| S11290 | 2025.07.26 | S13W39 |
 |
||||||||
| 14161 | 2025.07.27 2025.07.27 |
6 | 10 | 7 | S12E67 | 0080 | DAO | ESC |
 |
 |
was AR S11291 area: 0290 location: S12E64 |
| 14163 | 2025.07.27 2025.07.28 |
4 | 5 | 2 | N24W09 | 0010 | BXO | DRO |
 |
 |
was AR S11292 area: 0016 location: N24W08 |
| 14162 | 2025.07.27 2025.07.28 |
2 | 4 | 1 | N17W13 | 0010 | AXX | AXX |
 |
 |
was AR S11293 location: N18W11 |
| S11294 | 2025.07.27 | N21E07 |
 |
||||||||
| S11295 | 2025.07.28 | 4 | 3 | N17W67 | 0015 | CRO |
 |
||||
| S11296 | 2025.07.28 | 7 | 4 | S20W49 | 0020 | BXO |
 |
||||
| S11297 | 2025.07.28 | 2 | N01E19 | 0002 | BXO |
 |
|||||
| Total spot count: | 34 | 134 | 61 | ||||||||
| Sunspot number: | 134 | 304 | 201 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 67 | 176 | 103 | (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): | 147 | 167 | 161 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 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 | 160.9 (+1.5) (SC25 solar max) | 18.99 |
| 2024.11 | 199.6 | 195.3 | 154.1 | 157.1 (-3.8) | 9.33 |
| 2024.12 | 197.3 | 191.2 | 154.6 | 151.3 (-5.8) | 8.42 |
| 2025.01 | 190.3 | 184.2 | 137.0 | (146.1 projected, -5.2) | 13.17 |
| 2025.02 | 184.2 | 179.7 | 155.7 | (138.3 projected, -7.8) | 14.42 |
| 2025.03 | 163.7 | 162.1 | 134.2 | (131.9 projected, -6.4) | 15.96 |
| 2025.04 | 162.5 | 163.6 | 140.6 | (127.3 projected, -4.6) | 17.62 |
| 2025.05 | 135.3 | 138.3 | 79.2 | (122.0 projected, -5.3) | 17.26 |
| 2025.06 | 131.3 | 135.4 | 116.3 | (117.1 projected, -4.9) | 21.43 |
| 2025.07 | 136.7 (1) | 108.6 (2A) / 120.2 (2B) / 145.4 (2C) ISN average: 131.4. At this level the SSN for January 2025 will become 146.6 |
(112.9 projected, -4.2) | (12.7) | |
| 2025.08 | (108.1 projected, -4.8) | ||||
| 2025.09 | (103.8 projected, -4.3) | ||||
| 2025.10 | (99.9 projected, -3.9) | ||||
| 2025.11 | (97.6 projected, -2.3) | ||||
| 2025.12 | (96.0 projected, -1.6) | ||||
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 decreasing trend since September
2024 (using the average solar flux over 3 solar rotations as a proxy).
Compared to the peak of SC25 solar flux has been at a low level in both May
and June 2025. Taking a closer look at the 81 day (3 solar rotations)
average solar flux proxy, its peak was in early September 2024 and had on
May 12 decreased to less than half of the solar cycle flux range.
Subtracting the 81 day average of approximately 69 at solar cycle minimum
from all measurements, the SC25 range is 0 - 158.3.
All 365 day smoothed sunspot numbers peaked on October 11-12, 2024,
very likely making this the peak of SC25 (365 day smoothed peaks: STAR 1K: 236.1, STAR 2K: 364.3, NOAA SN: 156.0, ISN: 163.9). The 365d
smoothed solar flux peaked on October 13, 2024, just 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 whichever 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.
