The geomagnetic field was quiet on May 4. Solar wind speed at SOHO ranged between 384 and 441 km/sec. The high latitude magnetometer at Andenes recorded quiet to minor storm levels.
Solar flux density measured at 20h UT on 2.8 GHz was 162.0 - increasing 25.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 140.19. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.1). Three hour interval K indices: 21200212 (planetary), 00112322 (Boulder), 12221322 (Andenes).
The background x-ray flux is at the class C1 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 272) and in 10 active regions using 1K resolution (SN: 175) SDO/HMI images.
Region 13289 [N21W41] decayed slowly and quietly.
Region 13293 [N13E24] produced several C flares, but was generally
more quiet than on the previous day. A small magnetic delta remains in the
central spot section and M class flaring is possible. C1 flares: C1.8 @
22:00 UT
Region 13294 [S07E45] was quiet and stable.
Region 13295 [N16W49] decayed slowly and quietly.
Region 13296 [N17E35] developed further and has major flare
potential. The region has reversed polarities. C1 flares: C1.9 @ 07:37 UT
Region 13297 [N08E51] was quiet and stable. The region has a large
penumbral area, however, the magnetic layout is fairly simple. An M class
flare is possible.
New region 13298 [S15E34] emerged on May 3 and was numbered the next
day by SWPC as the region began to decay.
New region 13299 [S07E68] rotated into view on May 3 with SWPC
numbering the region the following day.
Spotted regions not observed (or interpreted
differently) by SWPC:
S8497 [S17W79] reemerged with a tiny spot.
S8505 [N19E10] was quiet and stable.
New region S8528 [S04E72] rotated into view.
New region S8529 [S22E81] was observed with tiny spots as the
region began to rotate into view.
New region S8530 [S21E22] was observed with
tiny spots in an old plage area.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C2.5 | 00:41 | 13288 | GOES18 | ||
| C3.3 | 00:57 | 13288 | GOES18 | ||
| C4.9 | 02:15 | 13288 | GOES18 | Simultaneous flare in AR 13296 | |
| C4.0 | 02:54 | 13288 | GOES18 | ||
| C2.6 | 03:53 | 13296 | GOES18 | ||
| C5.2 | 05:04 | 13293 | GOES18 | ||
| C4.4 | 05:09 | S8529 | GOES18 | ||
| C2.0 | 06:36 | 13288 | GOES18 | ||
| M3.9 | 08:44 | 13296 | GOES18 | LDE. CME. Moderate type II and IV radio sweeps | |
| C7.1 | 10:08 | 13293 | GOES18 | ||
| C2.8 | 13:01 | 13288 | GOES18 | ||
| C3.1 | 13:22 | 13293 | GOES18 | ||
| C2.8 | 14:01 | 13293 | GOES18 | ||
| C2.8 | 14:33 | 13288 | GOES18 | ||
| C2.2 | 15:06 | S8505 | GOES18 | ||
| C2.5 | 16:05 | 13293 | GOES18 | ||
| C3.3 | 18:11 | 13293 | GOES18 | ||
| C6.3 | 18:48 | 13288 | GOES16 | ||
| C3.5 | 19:43 | 13288 | GOES16 | ||
| C2.6 | 20:16 | S8528 | GOES16 | ||
| C2.1 | 20:42 | S8528 | GOES16 | ||
| C2.5 | 21:29 | 13288 | GOES16 | ||
| C2.0 | 23:12 | 13288 | GOES16 |
May 2-3: No obviously Earth directed CMEs were
observed.
May 4: A CME was observed after the M3 flare in AR 13296 at 08:44 UT.
The CME will probably not reach Earth, however, if the CME is slightly wider
than initial observations indicate, there is a chance of weak effects on May
7-8. A faint full halo CME was observed a little later coinciding with a
weak type IV radio sweep. The source of this event is uncertain and may be
backsided. The most likely frontsided candidate is a C7.1 flare at 10:08 in
AR 13293.
[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 southern hemisphere coronal hole (CH1144) was Earth facing on May 2-3. A recurrent northern hemisphere coronal hole (CH1145) could rotate across the central meridian on May 4. Another northern hemisphere coronal hole (CH1146) will likely become Earth facing on May 8-9.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor.
A quiet geomagnetic field is expected on May 5. Quiet to active conditions are possible on May 6-7 due to effects from CH1144.
| Coronal holes (1) | Coronal mass ejection (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 |
Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 13287 | 2023.04.23 2023.04.24 |
S25W77 | location: S27W65 | ||||||||
| 13289 | 2023.04.25 2023.04.25 |
4 | 10 | 4 | N20W41 | 0010 | BXO | BXO |
 |
 |
area: 0020 |
| S8497 | 2023.04.25 | 1 | S17W79 | 0001 | AXX |
 |
|||||
| 13292 | 2023.04.25 2023.04.27 |
N14W40 | location: N17W33 | ||||||||
| S8505 | 2023.04.29 | 5 | N19E10 | 0006 | BXO |
 |
 |
||||
| S8506 | 2023.04.29 | S10W13 |
 |
||||||||
| 13293 | 2023.04.30 2023.04.30 |
14 | 45 | 24 | N13E21 | 0240 | DAC | EAI |
 |
 |
beta-delta area: 0380 location: N12E24 |
| S8507 | 2023.04.30 | N20W49 | |||||||||
| 13295 | 2023.04.30 2023.05.02 |
3 | 3 | 1 | N16W47 | 0010 | BXO | BXO |
 |
 |
location: N17W49 area: 0006 |
| S8509 | 2023.04.30 | S25E26 | |||||||||
| S8511 | 2023.04.30 | N09W43 | |||||||||
| S8512 | 2023.04.30 | S12W42 | |||||||||
| S8513 | 2023.04.30 | S31W48 | |||||||||
| S8514 | 2023.04.30 | N33W09 | |||||||||
| S8515 | 2023.05.01 | S11E03 | |||||||||
| 13294 | 2023.05.01 2023.05.02 |
1 | 1 | 1 | S08E44 | 0120 | HSX | HSX |
 |
 |
area: 0220 location: S07E45 |
| S8517 | 2023.05.01 | N00W21 | |||||||||
| S8518 | 2023.05.01 | S03W43 | |||||||||
| S8519 | 2023.05.01 | N16W56 | |||||||||
| S8520 | 2023.05.01 | S39W42 | |||||||||
| 13296 | 2023.05.02 2023.05.02 |
11 | 23 | 15 | N16E34 | 0300 | DKI | DAC |
 |
 |
area: 0480 reversed polarities |
| 13297 | 2023.05.02 2023.05.02 |
18 | 32 | 20 | N08E50 | 0500 | EKI | EKC |
 |
 |
location: N08E51 area: 0880 |
| S8523 | 2023.05.02 | N06W00 | |||||||||
| S8524 | 2023.05.02 | S07W35 | |||||||||
| 13298 | 2023.05.03 2023.05.04 |
2 | 4 | 2 | S16E32 | 0010 | BXO | CRO |
 |
 |
location: S15E34 |
| 13299 | 2023.05.03 2023.05.04 |
6 | 10 | 5 | S06E69 | 0030 | DAO | DAO |
 |
 |
area: 0070 location: S07E68 |
| S8527 | 2023.05.03 | N23W17 |
 |
||||||||
| S8528 | 2023.05.04 | 2 | 1 | S04E72 | 0050 | HSX |
 |
||||
| S8529 | 2023.05.04 | 2 | S22E81 | 0003 | AXX |
 |
|||||
| S8530 | 2023.05.04 | 4 | 2 | S21E22 | 0008 | BXO |
 |
||||
| Total spot count: | 59 | 142 | 75 | ||||||||
| Sunspot number: | 139 | 272 | 175 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 94 | 180 | 113 | (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): | 153 | 150 | 140 | ||||||||
| 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 |
| 2021.09 | 87.0 | 88.2 | 51.3 | 40.2 (+4.8) | 6.33 |
| 2021.10 | 88.9 | 88.3 | 37.4 | 45.2 (+5.0) | 7.38 |
| 2021.11 | 86.2 | 84.4 | 34.8 | 50.8 (+5.6) | 9.83 |
| 2021.12 | 103.0 | 99.8 | 67.5 | 55.9 (+5.1) | 6.40 |
| 2022.01 | 103.8 | 100.5 | 55.3 | 60.1 (+4.2) | 8.92 |
| 2022.02 | 109.1 | 106.5 | 60.9 | 64.7 (+4.6) | 10.46 |
| 2022.03 | 117.0 | 115.8 | 78.6 | 68.7 (+4.0) | 10.20 |
| 2022.04 | 130.8 | 131.7 | 84.0 | 73.0 (+4.3) | 11.79 |
| 2022.05 | 133.8 | 136.8 | 96.5 | 77.4 (+4.4) | 7.48 |
| 2022.06 | 116.1 | 119.8 | 70.3 | 81.1 (+3.7) | 8.20 |
| 2022.07 | 125.4 | 129.5 | 91.4 | 86.7 (+5.6) | 9.51 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.5 (+5.8) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.4 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.7 (+2.3) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | (100.4 projected, +1.7) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | (104.1 projected, +3.7) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | (110.1 projected, +6.0) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (115.2 projected, +5.1) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 122.6 | (118.3 projected, +3.1) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 96.4 | (123.7 projected, +5.4) | 13.3 |
| 2023.05 | 153.6 (1) | 11.7 (2A) / 121.3 (2B) / 145.9 (2C) | (129.3 projected, +5.6) | (6.3) | |
| 2023.06 | (132.5 projected, +3.2) | ||||
| 2023.07 | (132.0 projected, -0.5) | ||||
| 2023.08 | (133.0 projected, +1.0) | ||||
| 2023.09 | (136.4 projected, +3.4) | ||||
| 2023.10 | (138.3 projected, +1.9) | ||||
| 2023.11 | (141.4 projected, +3.1) | ||||
| 2023.12 | (142.5 projected max SC25) | ||||
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 30 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: SIDC-SILSO.
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.
