Regular readers, if there are any, will remember the discussion earlier this year about unusual 'metallic bursts' of 6m signals seen when listening across the Atlantic from Wales.
In general, others I've spoken to are quite certain that these very ghostly-sounding echoes are simply meteor 'pings'.
I'm certainly no expert on the 6m band, neither am I very well-equipped for it; I have a 2-element quad, though it has achieved very good DX over the years.
What attracted me to these metallic bursts is the fact that I have never noticed them before I turned my antenna towards the US. For many years, my antenna has been fixed towards the SSE - towards Europe.
Now, the number of sporadic meteors entering a volume of atmosphere visibile to any given observer on the ground is very high. Settled numbers are hard to come by, but peer-reviewed papers often give a value of several thousand per day. From work I did with the University of Bath (actually, with identical SKiYMET radars), I know that number is reasonable. Here's an example plot of one 24 hour period, for example:
Since 2008, other studies have found a higher sporadic rate, closer to ~9,000 per day. So, we can expect, at the very least, about 2 sporadic VHF meteor pings from any given observing location per minute, and perhaps up to 6 per minute on more recent data. During meteor showers, the rate is obviously much higher.
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| SKiYMET radar at Esrange, Sweden. (C) University of Bath/N. Mitchell. |
Listening today, beaming Europe on an early August Saturday morning, when there are obviously a large number of 6m operators active, I can hear no metallic bursts at all. I heard one meteor ping, which was very short-lived - just a few milliseconds long.
Here's the map of activity this morning, together with the paltry number of receptions of my signals:
Having listened for the best part of an hour, I heard absolutely no metallic bursts at all.
There is no question that there are large numbers of meteors coming in all day, every day. So, the obvious question to ask those who assert this phenomenon is simply meteor bursts is: why can we not hear them all the time?
Let's see how many metallic bursts we can hear on 11-13 August, as the Perseids reach their peak. I will listen to Europe and transatlantic...
2 comments:
After reading you post I turned my antenna towards Japan again (35 degrees). Propagation at that moment was direction 130 degrees. At 35 degrees I decoded almost nothing except 1 station from Norway (LA9DAA) and yes I heard a few mettalic bursts. Will try late afternoon direction USA. I will now record with JTDX save so you'll be able to see what happens. 73, Bas
Thanks for your continued interest, Bas. Helpfully, there are many tens of 6m stations active today (Sunday, 09 August), but propagation has just died around lunchtime. I can hear no Es, and no bursts, whether meteors or otherwise, at all. Complete silence. That is not consistent with meteors being the cause of these bursts.
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