Solar Terrestrial Activity Report

Last major update issued on June 10, 2005 at 04:20 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 4, 2005)]

Recent activity

The geomagnetic field was inactive to quiet on June 9. Solar wind speed ranged between 348 and 427 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 116.1. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.9).
Three hour interval K indices: 11022221 (planetary), 10003112 (Boulder).

The background x-ray flux is at the class B2 level.

At midnight there were 6 spotted regions on the visible solar disk. The solar flare activity level was low. A total of 2 C class events was recorded during the day.

Region 10772 decayed slowly and quietly.
Region 10773 decayed slowly and quietly, the leader spot could disappear today.
Region 10775 developed further and has two magnetic delta structures, one near the southern edge of the main penumbra and another one in the trailing penumbra (which could merge with the main penumbra if growth continues)  An M class flare is possible. Flare: C1.5 long duration event peaking at 13:34 UTC.
Region 10776 developed slowly. Complexity increased as positive polarity flux emerged near the southern edge of the large leading penumbra. A major flare is possible. Flare: C1.0 at 16:31 UTC.

Spotted regions not numbered by NOAA/SEC:
[S556] This region emerged on June 9 just south of region 10775 and currently has its spots aligned along a north-south axis instead of the usual east-west orientation. Location at midnight: N05E05.
[S557] A new region emerged near the northeast limb on June 9. Location at midnight: N05E67.

Coronal mass ejections (CMEs)

June 7 and 9: No obvious fully or partly Earth directed CMEs were observed in LASCO images.
June 8: At least a partial halo CME was observed in LASCO C3 images during the late afternoon and early evening. The ejected material was first observed over the southwest limb and was likely related to a filament eruption to the north of region 10772.

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

No obvious coronal holes are currently near Earth facing positions.

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 quiet to unsettled on June 10. The CME observed on June 8 could reach Earth late on June 11 or early on June 12 and cause unsettled to active conditions. Quiet to unsettled is likely on June 13.

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 very 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 stations tonight: Radio Cristal del Uruguay and Radio Rafaela (Argentina). On 1510 kHz Radio Belgrano was dominant while AM Restauración on 1630 kHz had a much better signal than what I usually observe.

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% 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.