The geomagnetic field was at quiet to minor storm levels on May 4 under the influence of effects from CH1290. Solar wind speed at SOHO ranged between 605 and 803 km/sec, averaging 660 km/sec (-30 km/sec compared to the previous day). The high latitude magnetometer at Andenes recorded unsettled to major storm levels. The above 10 MeV proton flux was at background levels.
Solar flux density measured at 20h UT on 2.8 GHz was 159.0 - decreasing 3.3 over the previous solar rotation. The 365 days average solar flux at 1 AU was 194.48 (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 25 (STAR Ap - based on the mean of three hour interval ap indices: 24.9). Three hour interval K indices: 43524444 (planetary), 33534433 (Boulder), 56434456 (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 10 active regions using 2K resolution (SN: 229) and in 7 active regions using 1K resolution (SN: 135) SDO/HMI images.
AR 14076 [N06W62] was quiet and stable.
AR 14079 [N07E00] has multiple small magnetic delta configurations,
still, only low level C flares
were recorded. A major flare is possible. C1 flares: C1.1 @ 07:11, C1.8 @
16:27, C1.3 @ 17:46, C1.5 @ 19:41 UT
AR 14081 [N07E30] developed slowly and produced a few low level C
flares. C1 flares: C1.1 @ 06:13, C1.4 @ 06:34, C1.2 @ 21:47, C1.5 @ 23:53 UT
New AR 14082 [S11E61] rotated into view on May 3 and was
numbered the next day by SWPC as development continued. C1 flares: C1.4 @
08:17, C1.7 @ 10:10, C1.2 @ 14:42, C1.4 @ 16:06, C1.7 @ 21:04 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S11027 [S19W34] was quiet and stable.
S11033 [S15W14] was quiet and stable.
S11039 [N18W02] was quiet and stable.
New region S11043 [N18W09] emerged with tiny spots.
New region S11044 [N12W13] emerged with tiny spots.
New region S11045 [S26W02] emerged with tiny spots.
AR 14080 at the southwest limb produced a C1.5 flare at 20:50 UT
C2+ flares
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.4 | 11:33 | 14082 | |||
| C5.4 | 12:31 | 14082 |
May 2-4: 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 recurrent trans equatorial negative polarity coronal hole (CH1290) rotated into an Earth facing position on May 1. A recurrent southern hemisphere negative polarity coronal hole (CH1291) will be rotating across the central meridian May 4-6.
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 fair.
The geomagnetic field is expected to be at quiet to unsettled levels on May 5-6. Quiet to active levels are possible on May 7-9 due to effects from CH1291.
| 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 | ||||||||||
| 14072 | 2025.04.22 2025.04.23 |
S19W85 |
was AR S11011 location: S20W80 |
||||||||
| 14076 | 2025.04.23 2025.04.25 |
1 | 1 | 1 | N07W63 | 0050 | HSX | HSX |
 |
 |
was AR S11017 area: 0140 location: N06W62 |
| 14075 | 2025.04.23 2025.04.25 |
S11W78 |
was AR S11018 location: S09W72 |
||||||||
| 14077 | 2025.04.24 2025.04.25 |
S17W66 |
was AR S11020 location: S18W58 |
||||||||
| S11021 | 2025.04.24 | N19W52 | |||||||||
| S11027 | 2025.04.26 | 6 | S19W34 |
 |
 |
||||||
| 14079 | 2025.04.28 2025.04.28 |
30 | 74 | 42 | N08E01 | 1200 | EKC | EKC |
 |
 |
beta-gamma-delta was AR S11028 area: 1520 location: N07E00 |
| S11029 | 2025.04.29 | S22W30 | |||||||||
| S11030 | 2025.04.29 | N12W17 | |||||||||
| S11033 | 2025.05.01 | 4 | S15W14 | 0006 | BXO |
 |
 |
||||
| 14081 | 2025.05.01 2025.05.03 |
4 | 15 | 10 | N08E30 | 0030 | DAO | DAI |
 |
 |
was AR S11034 area: 0110 location: N07E30 |
| S11035 | 2025.05.01 | S14E04 |
 |
||||||||
| 14080 | 2025.05.02 2025.05.03 |
2 | S12W89 | 0010 | BXO |
 |
was AR S11036 location: S12W86 rotated out of view |
||||
| S11037 | 2025.05.02 | N06W31 | |||||||||
| S11038 | 2025.05.03 | N04W23 |
 |
||||||||
| S11039 | 2025.05.03 | 7 | 2 | N18W02 | 0012 | BXO |
 |
 |
|||
| 14082 | 2025.05.03 2025.05.04 |
5 | 15 | 8 | S11E65 | 0060 | DAO | DRI |
 |
 |
beta-gamma was AR S11040 area: 0080 |
| S11041 | 2025.05.03 | S17E42 |
 |
||||||||
| S11042 | 2025.05.03 | S03E24 |
 |
||||||||
| S11043 | 2025.05.04 | 2 | 1 | N18W09 | 0007 | BXO |
 |
||||
| S11044 | 2025.05.04 | 2 | 1 | N12W13 | 0005 | AXX |
 |
||||
| S11045 | 2025.05.04 | 3 | S26W08 | 0004 | BXO |
 |
|||||
| Total spot count: | 42 | 129 | 65 | ||||||||
| Sunspot number: | 92 | 229 | 135 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 67 | 152 | 88 | (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): | 101 | 126 | 108 | ||||||||
| 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 |
| 2023.11 | 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 | 160.8 (+1.4) | 18.99 |
| 2024.11 | 199.6 | 195.3 | 154.1 | (159.0 projected, -1.8) | 9.33 |
| 2024.12 | 197.3 | 191.2 | 154.6 | (155.2 projected, -3.8) | 8.42 |
| 2025.01 | 190.3 | 184.2 | 137.0 | (149.7 projected, -5.5) | 13.17 |
| 2025.02 | 184.2 | 179.7 | 154.7 | (141.6 projected, -7.1) | 14.42 |
| 2025.03 | 163.7 | 162.1 | 134.2 | (135.1 projected, -6.5) | 15.96 |
| 2025.04 | 162.5 | 163.6 | 140.6 | (130.5 projected, -4.6) | 17.9 |
| 2025.05 | 153.9 (1) | 8.6 (2A) / 66.5 (2B) / 133.5 (2C) | (125.2 projected, -5.3) | (29.2) | |
| 2025.06 | (120.3 projected, -4.9) | ||||
| 2025.07 | (116.1 projected, -4.2) | ||||
| 2025.08 | (111.4 projected, -4.7) | ||||
| 2025.09 | (107.1 projected, -4.3) | ||||
| 2025.10 | (103.2 projected, -3.9) | ||||
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. STAR 1K 365d peak: 236.1, STAR 2K 365d peak: 364.3, NOAA SN 365d peak: 156.0, ISN 365d peak: 163.6. 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.
