Tuesday, December 05, 2006

Solar Activity

The following appeared on QRP-L today, courtesy of Paul Harden NA5N:

Today's X9 flare was indeed quite a surprise, not only to us hams,
but to the scientific community as well. The flare occured right on
the east limb of the sun, that is, just coming into view, such that the
active region that produced it has not yet been viewed. This region
will be rotating into view over the next day, and over the next two
weeks will move across the surface of the sun (from east to west, or
left to right on most solar images).

Since this flare was on the east limb, Earth will experience on the
speed-of-light emissions (ionizing radiation and the radio storms) - NOT a subsequent severe major geomagnetic storm. Although, NOAA has predicted an A=20 (minor storm)
for Thursday, anticipating a glancing blow from the shockwave. It will not be a direct hit. However, over the next week and a half, further solar flares from region 0929/0930, as it nears the center of the sun, could cause major geomagnetic disturbances on Earth.

I talked to our head solar astronomer, Dr. Tim Bastian, who said the
40-ft. and 300-ft. antennas at Green Bank, WVa are now mapping this
area of the sun, trying to get some spatial resolution to see what this area looks like - difficult when it is right on the limb. Additionally, there are some pretty images of the Type II and Type IV sweeps on their radiometer. He has given me permission to pass on the following information. This is his website of the Green Bank solar radio burst spectrometer (GBSRBS), which is a newly created and EXPERIMENTAL website you might find interesting, though it has not been announced/released for public use yet (but released to QRP-L by permission). It is at:
Click on SELECTED EVENTS, then Type II and Type IV. Type II sweeps are caused by the shockwave of the flare punching through the magnetic field lines of the disturbance. They "sweep" from higher frequencies (50-300MHz) to lower frequencies (5-20MHz,
depending on the intensity of the shockwave). On earth, they will sound like bursts of static flying through your passband, much like ignition noise.

This X9 has been producing Type II events. Type IV sweeps are more continuum noise generated by the solar flare, though bounded in frequency to the 10-100MHz or so range, though effects much higher are not uncommon for a large flare. On earth, the Type IV sweeps
causes an overall increase in the HF noise level. This X9 has been producing Type IV events.

Now go to the DAILY SUMMARIES, click on DEC (December) and 2006. Click on Dec. 05 under the "BI 12-62 MHz" column. This is the Bruny Island Radio Spectrometer in Tasmania, which shows today's events so far. Can you see the Type II sweeps (going from the high to lower
frequencies)? And, the Type IV continuum noise?

The NRAO radio burst spectrometer is also real time, however, it is not updated on this PUBLIC website until the end of the UTC day, so Dec.05 is a bit blank yet. However, look at it later, which will give you a real-time (at least at the time -hi) spectrum of what happened to the HF bands down to 12MHz. You can compare it to Dec.04 (yesterday), which is pretty boring. Again, this will soon be an official NRAO (National Radio Astronomy Observatory) public website, and soon to have the daily real-time spectrograph on it, but still under development. Dr. Bastian was kind enough to allow me to share it with those hams so interested.

Lastly, Dr. Bastian is also observing, etc. to determine the effects of this flare to our upper ionosphere, and interested to know what effects this is or has had on HF propagation. There are facilities that measure these things, but it will be at the end of the UTC day or later before their
data is released. I am at work and no access to any HF gear. So, for those of you who have been on the bands since this morning, let me know (either private or via QRP-L) if you heard any Type II sweeps (the bursty, ignition noise stuff and approx. what time and frequency), an overall increase in noise (type IV), or if you experienced an HF black-out or near blackout condition. State your approx. location.

It is hard for some of these astronomers to realize there is a fleet of people out there who are experiencing these things real-time on ham radio. A sampling of reports across the country of noted effects could be helpful right now (as some of the propagation study instruments are shut down during the solar miniumum). I'll pass on anything interesting that might result from todays solar observing we're doing on this.

Thanks and 72,
Paul NA5N
National Radio Astronomy Observatory (NRAO)
Very Large Array (VLA) Radio Telescope
Socorro, New Mexico
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73 de Larry W2LJ

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