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[A-DX] Sudden Ionosperic Disturbances - nicht immer ist die Sonne schuld
- Subject: [A-DX] Sudden Ionosperic Disturbances - nicht immer ist die Sonne schuld
- From: Günter Lorenz <glorenz@xxxxxxxxxxxxx>
- Date: Thu, 6 Jan 2005 19:13:10 +0100
Diese Meldung schien mir doch interessant genug für eine Weiterleitung aus der Mailing-Liste des Medium Wave Circle. 73, Günter -----Originalnachricht----- Von: Paul Crankshaw Gesendet: 05.01.2005 10:11 Betreff: [mwc] Sudden Ionosperic Disturbances Forwarded from NDB-List, which in turn was forwearded from QRP-List There have been some episodes over the past week of some very strange Sudden Ionospheric Disturbances, or SIDs. These have not been caused by solar flares or the like, but rather from GRBs ... Gamma Ray Bursts, from very distant objects, like several hundred light years away. The biggest recent event was on December 27, 2004 when a massive gamma ray burst hit the earth about 2130 UTC from a Magnetar called SGR-1806. This GRB was so powerful that it was able to ionize our ionosphere, just like a solar flare, and cause ionospheric absorption down to the VLF frequencies. This indicates a GLE, a Ground Level Event, meaning the ionizing radiation from the GRB penetrated our atmosphere, all the way to ground level. There are amateur astronomers of sorts who monitor the signal strength from high powered VLF transmitters, such as the Navy stations NAA, NPM, NLK, etc. At VLF, signal strengths are fairly constant, varying a bit during day and night. Some of these amateur stations show a sudden absorption of signals at VLF due to the arrival of the GRB's. Some of their plots can be seen at: http://aavso.org Click on the "GCN #2932" button for the SID plots. Very interesting. For the real neophytes out there, http://gcn.gsfc.nasa.gov/gcn3_archive.html This is the clearinghouse for all observatories and satellites doing GRB monitoring and/or observing. A little on the heavy side, including several reports about the observing we're doing at the Very Large Array (VLA) radiotelescope on SGR-1806. Our normal observing schedule has been interupted to observe this strange phenomenon. The VLA has found SGR-1806 and is making images of it daily right now. It's not clear yet what SGR-1806 is, or was, other than something that possibly blew up big time, perhaps a collapsing pulsar, that has spewed debris and electrons out into space, traveling from 0.3 to 0.7 times the speed of light. It was the initial explosion, on Dec. 27th, that showered gamma rays into the earths ionosphere. This is an explosion that occured 200+ years ago, and the shockwave of gamma rays is so powerful, it was able to ionize our E and F layers, and absorb VLF propagation. Pretty impressive. -- ----------------------------------------------------------------------- Diese Mail wurde ueber die A-DX Mailing-Liste gesendet. Admin: Christoph Ratzer, OE2CRM http://www.ratzer.at ----------------------------------------------------------------------- Private Verwendung der A-DX Meldungen fuer Hobbyzwecke ist gestattet, jede kommerzielle Verwendung bedarf der Zustimmung des A-DX Listenbetreibers.
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