The geomagnetic field was quiet on May 23. Solar wind speed at SOHO ranged between 309 and 345 km/sec.
Solar flux at 20h UTC on 2.8 GHz was 66.5 (decreasing 0.7 over the previous solar rotation). The average 90 day 10.7 flux at 1 AU was 72.2 (The centered average 90 day SF at 1 AU hit a low of 67.77 on December 9, 2018. The centered 1 year average SF at 1 AU reached a minimum of 69.88 on August 18, 2018. The current 1 year average 1 AU SF is 70.63). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.3). Three hour interval K indices: 11111112 (planetary), 21132311 (Boulder)
The background x-ray flux is at the class A6 level.
At the time of counting spots (see image time), no spots were observed using 1K/2K resolution SDO/HMI images.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
May 21-23: No obviously Earth directed CMEs were observed in available LASCO imagery.
[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 southern hemisphere coronal hole (CH919) will likely rotate into an Earth facing position on May 24-25.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on May 24-26 becoming quiet to unsettled on May 27-28 due to effects from CH919.
| 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 numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. 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.
| Active region | Date numbered detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC | Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| S6173 | 2019.05.23 | N19W40 |
 |
cycle 25 | |||||||
| Total spot count: | 0 | 0 | 0 | ||||||||
| Sunspot number: | 0 | 0 | 0 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 0 | 0 | 0 | (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): | 0 | 0 | 0 | k * (sunspot number) As of May 7, 2016: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.80 for MSN 1K (MSN=Magnetic Sunspot Number) |
|||||||
| 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 (cycle peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (cycle peak) |
| 2017.12 | 71.6 | 69.3 | 8.2 | 15.1 (-0.3) | 7.33 |
| 2018.01 | 69.9 | 67.7 | 6.7 | 14.3 (-0.8) | 5.53 |
| 2018.02 | 72.0 | 70.2 | 10.6 | 12.6 (-1.7) | 6.40 |
| 2018.03 | 68.3 | 67.6 | 2.5 | 9.9 (-2.7) | 7.91 |
| 2018.04 | 70.0 | 70.5 | 8.9 | 7.9 (-2.0) | 6.80 |
| 2018.05 | 70.8 | 72.4 | 13.2 | 7.5 (-0.4) | 7.16 |
| 2018.06 | 72.5 | 74.7 | 15.9 | 7.3 (-0.2) | 6.83 |
| 2018.07 | 69.6 | 72.3 | 1.6 | 7.1 (-0.2) | 5.38 |
| 2018.08 | 69.1 | 70.8 | 8.8 | 6.8 (-0.3) | 8.98 |
| 2018.09 | 68.2 | 69.0 | 3.3 | 6.6 (-0.2) solar minimum candidate |
8.91 |
| 2018.10 | 69.6 | 69.1 | 4.9 | 6.9 (+0.3) | 6.49 |
| 2018.11 | 68.9 | 67.4 | 5.9 | (6.7 projected, -0.2) | 5.78 |
| 2018.12 | 70.0 | 67.8 | 3.1 | (6.3 projected, -0.4) | 6.10 |
| 2019.01 | 71.5 | 69.2 | 7.8 | (6.3 projected, 0.0) | 5.89 |
| 2019.02 | 70.6 | 68.9 | 0.8 | (6.8 projected, +0.5) | 6.88 |
| 2019.03 | 71.6 | 70.8 | 9.5 | (7.5 projected, +0.7) | 6.12 |
| 2019.04 | 72.4 | 72.9 | 9.1 | (8.3 projected, +0.8) | 6.06 |
| 2019.05 | (72.5) | 10.0 (2A) / 13.4 (2B) / 10.5 (2C) | (8.9 projected, +0.6) | (7.3) | |
| 2019.06 | (9.8 projected, +0.9) | ||||
| 2019.07 | (10.5 projected, +0.7) | ||||
| 2019.08 | (11.4 projected, +0.9) | ||||
| 2019.09 | (12.7 projected, +1.3) | ||||
| 2019.10 | (13.4 projected, +0.7) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
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.
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.
