Last major update issued on December 28, 2004 at 03:40 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update December 3, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update December 3, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update December 3, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update November 8, 2004)]
[Archived reports (last update December 24, 2004)]
The geomagnetic field was quiet to unsettled on December 27. Solar wind speed ranged between 448 and 581 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 96.9. The planetary A
index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.0).
Three hour interval K indices: 11311132 (planetary), 12311232 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.Region 10713 lost penumbral area, however, the region developed quickly during the latter half of the day as new magnetic flux emerged immediately to the south of the single penumbra. A magnetic delta structure could be forming in the new area. Minor M class flares are possible. This region was the source of an impulsive C7.2/1F flare at 00:10 UTC on December 28.
December 25-27: 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
No obvious coronal holes are currently in or near geoeffective positions.
Processed SOHO/EIT 284 image at 18:03 UTC on December 11. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to unsettled on December 28. Quiet conditions are likely on December 29-31.
|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, occasionally fair to good. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: WLAM Lewiston ME. Propagation was best towards the easternmost parts of the USA and Canada with stations like WIOD Miami on 610 and WBIX Natick on 1060 kHz.
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 DSO
at midnight, area 0080
|Total spot count:||1||10|
flux at Earth
|International sunspot number||Smoothed sunspot number|
cycle 23 sunspot max.
|2004.06||97.4||43.2||(42.2 predicted, -1.7)|
|2004.07||119.1||51.0||(40.6 predicted, -1.6)|
|2004.08||109.6||40.9||(39.0 predicted, -1.6)|
|2004.09||103.1||27.7||(37.1 predicted, -1.9)|
|2004.10||105.9||48.4||(34.9 predicted, -2.2)|
|2004.11||113.2||43.7||(33.0 predicted, -1.9)|
|2004.12||93.6 (1)||30.2 (2)||(30.7 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.