Last major update issued on May 20, 2005 at 04:10 UTC.
[Solar and
geomagnetic data - last month (updated daily)]
[Solar wind and
electron fluence charts (updated daily)]
[Solar cycles 21-23
(last update May 6, 2005)]
[Solar cycles 1-20]
[Graphical comparison
of cycles 21, 22 and 23 (last update May 6, 2005)]
[Graphical
comparison of cycles 2, 10, 13, 17, 20 and 23 (last update May 6, 2005)]
[Historical solar and
geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports
(last update May 15, 2005)]
The geomagnetic field was quiet to unsettled on May 19. Solar wind speed ranged between 422 and 596 km/sec. A high speed stream from CH166 was observed beginning early on May 20 at ACE.
Solar flux measured at 20h UTC on 2.8 GHz was 84.7. The planetary
A
index was 11 (STAR Ap - based on the mean of three hour interval ap
indices: 11.0).
Three hour interval K indices: 23322233 (planetary), 23322333 (Boulder).
The background x-ray flux is at the class A7 level.
At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10759 was quiet and stable and will rotate out of view at the northwest limb today.
New region 10765 rotated into view at the northeast limb on May 18 and was numbered by SEC the next day. The region decayed
slowly on May 19 and could become spotless today.
May 18-19: No obviously fully or partly potentially geoeffective CMEs were observed.
May 17: A very faint and slow full halo CME was observed after an M1.8 flare in region 10763 early in the day. This CME
could reach Earth early on May 20.
Coronal hole
history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28
days ago 27 days ago 26
days ago
A recurrent coronal hole (CH166) in the northern hemisphere was in an Earth facing position on May 17.
Processed SOHO/EIT 284 image at 01:06 UTC on May 20. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to minor storm on May 20 due to a high speed stream from CH166 and a weak CME. Quiet to unsettled is likely on May 21-23.
| 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) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next
48 hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along long distance north-south paths is poor to fair. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Rafaela (Argentina). On other frequencies propagation was best from Brazil (930 Rádio Metropolitana, 740 Rádio Sociedade, 1430 Rádio Clube Paranaense and 1100 Rádio Globo had the best signals) and Argentina.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. 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 SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
| Active region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10759 | 2005.05.08 | 1 | 1 | N12W75 | 0270 | HHX | classification was HKX at midnight |
| 10763 | 2005.05.12 | 2 | S16W35 | 0010 | BXO | spotless | |
| 10765 | 2005.05.19 | 1 | 1 | N09E65 | 0030 | HSX |
formerly region S550 classification was AXX at midnight, area 0010 |
| S548 | 2005.05.17 | S13W14 | plage | ||||
| S549 | 2005.05.18 | S12W21 | plage | ||||
| Total spot count: | 4 | 2 | |||||
| SSN: | 34 | 22 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2004.03 | 112.0 | 49.1 | 47.1 (-2.2) |
| 2004.04 | 101.2 | 39.3 | 45.5 (-1.6) |
| 2004.05 | 99.8 | 41.5 | 43.8 (-1.7) |
| 2004.06 | 97.4 | 43.2 | 41.6 (-2.2) |
| 2004.07 | 119.1 | 51.1 | 40.2 (-1.4) |
| 2004.08 | 109.6 | 40.9 | 39.2 (-1.0) |
| 2004.09 | 103.1 | 27.7 | 37.5 (-1.7) |
| 2004.10 | 105.9 | 48.0 | 35.9 (-1.6) |
| 2004.11 | 113.2 | 43.5 | (34.8 predicted, -1.1) |
| 2004.12 | 94.5 | 17.9 | (33.4 predicted, -1.4) |
| 2005.01 | 102.2 | 31.3 | (30.9 predicted, -2.5) |
| 2005.02 | 97.2 | 29.1 | (28.3 predicted, -2.6) |
| 2005.03 | 89.9 | 24.8 | (26.5 predicted, -1.8) |
| 2005.04 | 86.0 | 24.4 | (24.6 predicted, -1.9) |
| 2005.05 | 106.1 (1) | 45.2 (2) | (22.0 predicted, -2.6) |
1) Running average based on the daily 20:00 UTC observed solar flux
value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC)
sunspot number. The official international sunspot number is typically
30-50% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.
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