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Fall 2004 Issue |
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Intense July 2004 Aurora
A widespread, intense, and
long-duration aurora opening occurred July 25–27, 2004. Noteworthy were
the number of hours aurora QSOs were worked and how far south the aurora
went. This might have been the last widespread aurora opening of solar
Cycle 23. |
Sunspot 652 on July 23, 2004. (Image courtesy SOHO/MDI) |
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The late July auroras were sparked by multiple CMEs (coronal mass ejections) from giant sunspot number 652. This sunspot was so large it could be seen by the naked eye, and it harbored energy for M- and X-class solar flares. From July 20 through July 27 solar flares erupted from sunspot 652. On July 24–25 a strong geomagnetic storm began. On July 25 several M-class flares erupted powerfully from 652. These would spark aurora that was seen as far south as California, Nebraska, and Utah. The aurora occurred due to the high speed of the solar wind (clocked at over 1,000 km/s) and the IMF (interplanetary magnetic field) Bz vector pointed south. A south-pointing IMF allows the Earth’s magnetic field to link up with the sun’s, opening a door through which energy from the solar wind can reach the Earth’s atmosphere. On the evening of July 25 (26 UTC) radio aurora was workable as far south as Kansas, Oklahoma, and even Texas. I operated portable from EM18 and worked KØGU DN70 on 2-meter aurora at 0025 UTC, July 26 while running only 20 watts. Jay always has a great signal on aurora and worked south to Oklahoma and Texas. I made only a couple of 2-meter aurora QSOs besides Jay—WYØV EN13 and NØKQY DM98. I heard many stations, but with only 20 watts and a 7-element Yagi, I found it difficult to be heard. Radio aurora was spotted most of that night and on into the next morning, at which time it faded. The aurora returned with a vengeance the next evening. Spaceweather.com reported, “an intense geomagnetic storm began at 2300 UTC, July 26.” Radio aurora began to be worked around 2300 UTC. K5SW EM25 worked W2KV FN20 on 2-meter aurora at 2333 UTC. Seeing the aurora was back, I again drove out to EM18. I operate portable, as I live in a CC&R no-outside-antenna restricted neighborhood. This time I brought a 150 amplifier, which definitely helped!
The aurora had been going on for almost two
hours by the time I arrived at my operating location and got up the
2-meter Yagi. At 0110 UTC on July 27, I copied Peter, VE3AX, “59A” on
144.195 MHz working 8- and 9-area stations. I heard Peter work N8IE EN92
at 0112 UTC and called him after he signed. We worked at 0113 UTC. Peter
e-mailed, “You were really not that strong and was getting QRMed badly,
but had no trouble pulling you through. I was aiming at 300 degrees for
this QSO.” Peter is 1525 km from me. He was the best DX I worked on
2-meter aurora that evening. Click here to return to Fall 2004 highlights Click here to subscribe to VHF _________________ © Copyright 2004, CQ Communications, Inc. All rights reserved. This material may not be reproduced or republished, including posting to a website, in part or in whole, by any means, without the express written permission of the publisher, CQ Communications, Inc. Hyperlinks to this page are permitted.
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