Solar Terrestrial Activity Report

Last major update issued on June 17, 2005 at 04:25 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 quiet to major storm on June 16. Solar wind speed ranged between 397 and 688 km/sec. A solar wind shock was observed at ACE at 08:12 UTC. This was the arrival of the full halo CME observed on June 14.

Solar flux measured at 20h UTC on 2.8 GHz was 98.1. The planetary A index was 26 (STAR Ap - based on the mean of three hour interval ap indices: 26.4).
Three hour interval K indices: 12265443 (planetary), 22364443 (Boulder).

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

At midnight there were 4 spotted regions on the visible solar disk. The solar flare activity level was moderate. A total of 2 C and 1 M class events was recorded during the day.

Region 10775 rotated out of view at the northwest limb. Flares: C1.7 at 09:05 and a long duration M4.0 proton event peaking at 20:22 UTC. A strong type II and a weak type IV radio sweep was associated with this event.
Region 10776 added a few small spots. Flare: C1.6 at 02:02 UTC.
Region 10779 developed slowly and remained magnetically simply structured.

Spotted regions not numbered by NOAA/SEC:
[S560] This region emerged in the northeast quadrant on June 16. Location at midnight: N08E37.
[S561] A new region rotated into view at the southeast limb on June 16. Location at midnight: S06E76.

Coronal mass ejections (CMEs)

June 14: A full halo CME was observed in LASCO images after a long duration C4 event in region 10775 during the morning. With no available LASCO images covering the C7 long duration event later in the day, it is uncertain if there was another full halo CME then.
June 15-16: No obvious fully or partly Earth directed CMEs were observed in LASCO images. (LASCO images for the last 7 hours of June 16 are not available when I write this.)

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 at or 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.


The geomagnetic field is expected to be quiet to active on June 17-18 and quiet to unsettled on June 19.

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

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 very poor. Propagation along long distance north-south paths is good to very good. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Rafaela Argentina. Many stations from Brazil (huge signals were noted from some of the higher powered stations in São Paulo and Rio de Janeiro), Uruguay and Argentina were observed on other frequencies. 1510 kHz was very lively with a mix of Rádio Nordeste AM (Brazil), Radio Rincón (Uruguay) and Rádio Champaquí and Radio Belgrano (Argentina).

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.

Active region Date numbered SEC
Location at midnight Area Classification Comment
10775 2005.06.04 2   N10W86 0130 HAX rotated out of view
10776 2005.06.05 5 5 S05W77 0270 CKO  
10777 2005.06.10     N05W24     plage
10778 2005.06.15 1   N08W50 0010 AXX spotless
10779 2005.06.15 19 28 S17W05 0240 DAI classification was DKI at midnight, area 0440
S556 2005.06.09     N05W86     plage
S560 2005.06.16   2 N08E37 0010 HRX  
S561 2005.06.16   1 S06E76 0050 HSX  
Total spot count: 27 36  
SSN: 67 76  

Monthly solar cycle data

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)
2004.04 101.2 39.3 45.5 (-1.6)
2004.05 99.8 41.5 43.8 (-1.7)
2004.06 97.4 43.2 41.6 (-2.2)
2004.07 119.1 51.1 40.2 (-1.4)
2004.08 109.6 40.9 39.2 (-1.0)
2004.09 103.1 27.7 37.5 (-1.7)
2004.10 105.9 48.0 35.9 (-1.6)
2004.11 113.2 43.5 35.3 (-0.6)
2004.12 94.5 17.9 (34.8 predicted, -0.5)
2005.01 102.2 31.3 (32.8 predicted, -2.0)
2005.02 97.2 29.1 (30.4 predicted, -2.4)
2005.03 89.9 24.8 (28.8 predicted, -1.6)
2005.04 86.0 24.4 (26.9 predicted, -1.9)
2005.05 99.3 42.6 (24.3 predicted, -2.6)
2005.06 102.3 (1) 42.4 (2) (22.8 predicted, -1.5)

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.

[DX-Listeners' Club]