Solar Terrestrial Activity Report

Last major update issued on June 28, 2007 at 04:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update June 3, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 3, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 3, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update May 18, 2007)]

Recent activity

The geomagnetic field was quiet on June 27. Solar wind speed ranged between 348 and 387 km/s (average speed was 361 km/s, decreasing 12 km/s from the previous day).

Solar flux measured at 20h UTC on 2.8 GHz was 73.2. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.4). Three hour interval K indices: 22201122 (planetary), 22212211 (Boulder).

The background x-ray flux is at the class A1 level.

At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day. This was a C1.3 flare at 18:00 UTC from a source at the east limb.

Region 10961 developed slowly adding a few spots.

Coronal mass ejections (CMEs)

June 25-27: No obvious fully or partially Earth directed CMEs were observed in LASCO imagery.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent coronal hole (CH275) in the southern hemisphere was in an Earth facing position on June 25-27.

.

Processed SOHO/EIT 195 image at 19:48 UTC on June 27. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on June 28-30 due to effects from CH275.

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) Effects from a CME are likely to be observed at 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.

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
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10961 2007.06.25 5 3 S11E50 0180 CKO classification was CAO at midnight, area 0120
Total spot count: 5 3  
SSN: 15 13  

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)
2006.04 89.0 30.2 17.1 (-0.3)
2006.05 80.9 22.3 17.3 (+0.2)
2006.06 76.5 13.9 16.3 (-1.0)
2006.07 75.7 12.2 15.3 (-1.0)
2006.08 79.0 12.9 15.6 (+0.3)
2006.09 77.8 14.4 15.6 (+0.0)
2006.10 74.3 10.4 14.2 (-1.4)
2006.11 86.3 21.5 12.7 (-1.5)
2006.12 84.5 13.6 (12.1 predicted, -0.6)
2007.01 83.3 16.9 (11.7 predicted, -0.4)
2007.02 77.7 10.6 (11.1 predicted, -0.6)
2007.03 72.2 4.8 (10.7 predicted, -0.4)
2007.04 72.4 3.7 (10.9 predicted, +0.2)
2007.05 74.4 11.7 (11.0 predicted, +0.1)
2007.06 73.6 (1) 17.6 (2) (11.3 predicted, +0.3)

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% 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]