Solar Terrestrial Activity Report

Last major update issued on June 23, 2005 at 04:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 4, 2005)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 4, 2005)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 4, 2005)]
[Historical solar and geomagnetic data charts 1954-2004 (last update February 1, 2005)]
[Archived reports (last update June 21, 2005)]

Recent activity

The geomagnetic field was very quiet to unsettled on June 22. Solar wind speed ranged between 286 and 362 km/sec. A disturbance began late in the day. Early on June 23 this appears to be the arrival of a high speed stream from CH171.

Solar flux measured at 20h UTC on 2.8 GHz was 79.5. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.8).
Three hour interval K indices: 22121123 (planetary), 22120113 (Boulder).

The background x-ray flux is at the class A5 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day.

Region 10779 decayed and rotated partly out of view at the southwest limb.
Region 10780 decayed slowly and was mostly quiet. Flare: C1.8 at 16:33 UTC.

Coronal mass ejections (CMEs)

June 20-22: No obvious fully or partly Earth directed CMEs were observed in available LASCO images.

Coronal holes

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 (CH171) in the northern hemisphere was in an Earth facing position on June 20-22.

Processed SOHO/EIT 284 image at 01:06 UTC on June 6. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on June 23-24 due to a high speed stream from CH171 and quiet to unsettled on June 25.

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along long distance north-south paths is fair to poor. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. On other frequencies most of the observed stations were from Brazil with 920 and 970 kHz having the most interesting signals.

Active solar regions (Recent map)

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.

Monthly solar cycle data

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% lower.

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.