Last major update issued on October 26, 2004 at 04:00 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update October 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update August 28,
2004)]
[Archived reports (last update October 18, 2004)]
The geomagnetic field was quiet to active on October 25. Solar wind speed ranged between 418 and 509 km/sec under the influence of a high speed stream from coronal hole CH120. This coronal hole flow became less influential during the latter half of the day.
Solar flux measured at 17h UTC on 2.8 GHz was 139.6. The planetary A
index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 12.6).
Three hour interval K indices: 23343221 (planetary), 23343321 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 7 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 9 C class events was recorded during the day.
Region 10684 decayed further and lost nearly all trailing spots.Spotted regions not numbered by NOAA/SEC:
[S466] This region emerged on October 25 in the northeast quadrant. Location at midnight: N16E62.
October 23-25: No obviously Earth directed CMEs observed.
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 coronal hole (CH121) in the southern hemisphere will be in a geoeffective position on October 25-26.
Processed SOHO/EIT 284 image at 01:06 UTC on October 26. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet on October 26-28. Quiet to active is possible on October 29-30, maybe as early as the latter half of October 28, due to effects from coronal hole CH121.
| 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 fair to poor and improving. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela) and Radio Cristal del Uruguay at 01h UTC, later on WLAM Lewiston ME was noted as well. On other frequencies propagation was best towards the easternmost parts of the USA and Canada.
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 |
|---|---|---|---|---|---|---|---|
| 10684 | 2004.10.17 | 10 | 4 | S04W39 | 0100 | DAO |
classification was CAO at midnight, area 0080 |
| 10685 | 2004.10.18 | S07W69 | plage | ||||
| 10687 | 2004.10.19 | 48 | 55 | N12E03 | 0370 | EAI | |
| 10689 | 2004.10.21 | 3 | 1 | N12E22 | 0060 | HAX | |
| 10690 | 2004.10.22 | 2 | 2 | S01E40 | 0070 | HAX |
area was 0110 at midnight |
| 10691 | 2004.10.23 | 17 | 15 | N15E48 | 0150 | EAI | beta-gamma |
| 10692 | 2004.10.24 | 6 | 5 | S18E16 | 0110 | DAO | |
| S466 | emerged on 2004.10.25 |
5 | N16E62 | 0020 | BXO | ||
| Total spot count: | 86 | 87 | |||||
| SSN: | 146 | 157 | |||||
| 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) |
| 2003.08 | 122.1 | 72.7 | 60.0 (-1.7) |
| 2003.09 | 112.2 | 48.7 | 59.5 (-0.5) |
| 2003.10 | 151.7 | 65.5 | 58.2 (-1.3) |
| 2003.11 | 140.8 | 67.3 | 56.7 (-1.5) |
| 2003.12 | 114.9 | 46.5 | 54.8 (-1.9) |
| 2004.01 | 114.1 | 37.3 | 52.0 (-2.8) |
| 2004.02 | 107.0 | 45.8 | 49.3 (-2.7) |
| 2004.03 | 112.0 | 49.1 | 47.1 (-2.2) |
| 2004.04 | 101.2 | 39.3 | (44.6 predicted, -2.5) |
| 2004.05 | 99.8 | 41.5 | (40.9 predicted, -3.7) |
| 2004.06 | 97.4 | 43.2 | (38.0 predicted, -2.9) |
| 2004.07 | 119.1 | 51.0 | (36.2 predicted, -1.8) |
| 2004.08 | 109.6 | 40.9 | (34.6 predicted, -1.6) |
| 2004.09 | 103.1 | 27.7 | (32.8 predicted, -1.6) |
| 2004.10 | 99.2 (1) | 49.9 (2) | (30.5 predicted, -2.3) |
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.
| [DX-Listeners' Club] |