|Charts (* = updated daily)||Data and archive|
|Solar wind (*)||Solar and geomagnetic data - last month (*)|
|Electron fluence (*)||Archived daily reports and monthly data since 2003.01 (May 1, 2023)|
|Solar cycle||Solar cycles 23-25 (May 1, 2023)||Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)|
|Cycle 24-25 progress (May 1, 2023)||Noon SDO sunspot count 1K image / 4K (*)|
|Solar cycles 1-24 (July 1, 2020)||POES auroral activity level [October 2009 - December 2012]|
|Comparison of cycles 21-25 (May 1, 2023)||3rd SSN Workshop, Tucson, 2013|
|Comparison of cycles 12-14, 16, 24-25 (May 1, 2023)||4th SSN Workshop, Locarno, 2014|
|Solar polar fields vs. solar cycles (April 5, 2023)||Cycle 25 spots (final update December 25, 2019)|
|Solar cycles 24-25 transition using 365d smoothing||Research: Solar Cycle 25 Started on November 17, 2019 with 365 Days Smoothing|
The geomagnetic field was quiet to unsettled on May 25 under the influence of a high speed stream associated with CH1149. Solar wind speed at SOHO ranged between 533 and 669 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 152.1 - increasing 2.3 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 140.80. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.5). Three hour interval K indices: 33332232 (planetary), 33332322 (Boulder), 44344254 (Andenes).
The background x-ray flux is at the class B8 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 333) and in 10 active regions using 1K resolution (SN: 202) SDO/HMI images.
Region 13310 [S20W31] was mostly quiet and
stable. C1 flares: C1.3 @ 12:54 UT
Region 13311 [N19W14] decayed slowly and produced a few C flares. C1 flares: C1.8 @ 03:39, C1.3 @ 06:34, C1.6 @ 07:48, C1.5 @ 09:28, C1.3 @ 12:44, C1.1 @ 21:18, C1.0 @ 22:22 UT
Region 13312 [S25W11] was the source of the only M flare of the day despite having only small and tiny spots. C1 flares: C1.7 @ 02:34, C1.6 @ 09:04 UT
Region 13313 [N22W01] was quiet and stable.
Region 13315 [S18E19] developed further and could produce M class flares. C1 flares: C1.5 @ 13:52, C1.8 @ 17:32 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8580 [N20W43] was quiet and stable.
S8582 [S09W21] reemerged with a tiny spot.
S8588 [S13W28] was mostly quiet and stable. C1 flares: C1.2 @ 01:01 UT
S8589 [S21E03] was quiet and stable.
S8590 [N15W31] produced several C flares and could be developing a magnetic delta configuration. C1 flares: C1.9 @ 13:59, C1.8 @ 14:30, C1.4 @ 17:55 UT
S8591 [N12E40] was quiet and stable.
S8592 [N08E51] developed further and was quiet.
New region S8593 [N26E13] emerged with tiny spots.
|Magnitude||Peak time (UT)||Location||Source||Recorded by||Comment|
May 23-25: No obviously Earth directed CMEs were observed.
[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 coronal hole (CH1149) rotated across the central meridian on May 20-22.
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.
Quiet to unsettled conditions are likely on May 26 due to effects from CH1149. Quiet conditions are expected for May 27-28.
|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
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlays
merged with AR 13311 on 2023.05.22
SWPC resurrected the region on 2023.05.24
see AR S8590
split off from AR 13311
|Total spot count:||61||203||102|
|Sunspot number:||121||333||202||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||99||242||141||(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):||133||183||162|
|Month||Average solar flux||International sunspot number
|Smoothed sunspot number (4)||Average ap
|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|
(Solar minimum using 365d smoothing:
November 17, 2019)
(ISN 13 months smoothed
|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
|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)||13.40|
|2023.05||155.6 (1)||99.4 (2A) / 123.3 (2B) / 152.9 (2C)||(129.3 projected, +5.6)||(12.2)|
|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.