Last major update issued on October 27, 2004 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 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 very quiet on October 26. Solar wind speed ranged between 386 and 458 km/sec, gradually decreasing all day.
Solar flux measured at 17h UTC on 2.8 GHz was 136.7. The planetary A
index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.8).
Three hour interval K indices: 10001110 (planetary), 11002210 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there were 8 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 6 C class events was recorded during the day. A C1.0 flare at 22:25 had its origin behind the southwest limb.Region 10684 was quiet and stable.
Spotted regions not numbered by NOAA/SEC:
[S466] This region emerged on October 25 in the northeast quadrant. Location at midnight: N17E47.
[S467] A new region emerged in the southwest quadrant near coronal hole CH121 on October 26. Location at midnight: S08W13.
October 24-65: 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 was 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 27-28. 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 and improving. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración and WLAM Lewiston ME. On other frequencies propagation was best towards the easternmost parts of the USA and Canada and Cuba. Greenland on 650 kHz had a much better signal than 24h earlier and was audible as early as 18h UTC.
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
|Location at midnight||Area||Classification||Comment|
classification was HSX
classification was HSX
at midnight, area 0060
classification was CAO
|Total spot count:||64||98|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|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||100.6 (1)||53.9 (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.