Observing Meteors by Radio

JAS & Observing Meteors by Radio

JAS has recently started observing meteors by radio, ten trials were done until we successfully observed meteors by radio, the first eight trials were done in Amman (The capital of Jordan) in which the israeli radio stations affected our observations, and thus we held the 9th trial in Sahab City (20 km away from Amman), and we succeeded in observing one meteor only. However, the israeli station was still annoying ! So we decided to move to the desert, specifically in Al-Azraq desert (80 km away from Amman), and so on 7 September 1998 we went to the desert. During the first hours we just did some experiments for observing meteors by radio. Later on, after we were sure that every thing was going fine we started seriously observing on 8 September 1998 at 1:44 am (local time), and the observations lasted till 6 am (local time), with an effective observing time of 3 hours exactly, at which we observed 173 meteors by radio. The observers were:-

How it Works ?

When a meteoroid enters the atmosphere, the particle will completely ionize its trail at an altitude that ranges between 120 km and 80 km, and the ionized trails are capable of reflecting radio signals from terrestrial stations, which include those broadcast by commercial FM and TV stations. The advantage of of this kind of observation that it can be done in daylight and during cloudy or rainy weather ! Also the moon's light is no more annoying when observing meteors by radio. Radio detection rates of meteors tend to be higher than visual observation rates. This occurs because particles down to 10-5 kg can be detected visually, while particles down to 10-10 kg can be detected by radio. Assuming a density of 1 t/m3, these mass limits correspond to diameter of about 3 mm and 0.06 mm, respectively. By radio observation you can detect meteors down to 8th magnitude !

The easiest way to observe meteors by radio is to use commercial FM radio (preferable digital), and attach it to an antenna (preferable FM Yagi antenna), then try to find an empty frequency from 87.5-108.0 MHz, where you do not hear any kind of music or talking, and is being used by a distant transmitter (mostly a distant FM radio station) about 300-2000 km away from your location of observation (preferably 500-800 km). It is better to choose a station that transmits over 30 kilowatts, and point the antenna towards the station. Now, all what you hear is a continuous static, and when a meteor passes and if its position is suitable then it will reflect the waves of the distant station and you will hear it, the period varies from 0.1 second to several seconds or even minutes (mostly on the order of 0.25 second). They are small segments of what is being transmitted. They sound like bumps, thumps and chirps. The longer signals are recognizable pieces of music or talking. To distinguish the signals reflected from a meteor than others such as aeroplanes, the signals reflected from a meteor is very sudden, mostly loud and clear, and end gradually.

Our Results & Examples of Meteors We Heard

Below are the results achieved during our first experiment in observing meteors by radio in the 21st Astronomical camp dedicated to observe meteors by radio, 173 meteors were observed in three hours.

7-8 September 1998 (Times are UT)
22:44 - 23:44 : 44 meteors.
00:05 - 01:05 : 65 meteors.
02:00 - 03:00 : 64 meteors.

FAQ on Observing Meteors by Radio

References and Links

* References:-

* Links:
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By Moh'd Odeh. Jordanian Astronomical Society (JAS), All Rights Reserved. This material may not be reproduced in any form without permission. For more information SendE-mail or contact us at : The Jordanian Astronomical Society (JAS),P.O.Box 35022, Amman 11180 Jordan
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