Automated Meteor Observations at the Astronomical Observatory of the University of Ghent

What are meteors?

Meteors are caused by small dust particles entering the Earth's atmosphere. Due to the friction with the air, the immediatly start burning, procuding a long trail of ionized gas. Often, this trail can be observed from Earth (called a "shooting star").

Dust particles are not homogeneously spread over our Solar System, because they are often associated with an ancient comet, fallen into debris. Such a dusty region causes enhanced meteor activity, called a "meteor shower". Famous meteor showers are the Perseids (in August), the Geminids (in December), etc. Knowledge of these meteor showers, together with their intensity and duration, allows one to obtain additional information about the dust distribution in our Solar System.

Radio observations of meteors

One of the projects at the Observatory of the University of Ghent is the automated observation of meteors using radio techniques. The experimental setup consists in a sensitive receiver which is tuned to a distant broadcast station in the FM band. Due to the radio horizon, there is no signal receiver under normal circumstances. However, if a meteor enters the atmosphere, it leaves an ionized trail which is able to reflect the signal in the direction of the receiver's antenna. An incoming meteorite can therefore be associated with a sharp peak in the signal strength of the receiver.

Principle of Forward Scattering

Computerized recording and interference rejection by anticoincidence measurements

The signal strength of the receiver is continuously monitored by a computer (using an analogue-to-digital convertor). Each peak in the signal is detected and stored on hard disk, togheter with the time of occurrence.

Unfortunately, peaks in the signal strength of the receiver can also be caused by local interference sources, such as PC's, ingition motors, lightnings, etc. Therefore, it is of the utmost importance to incorporate a control mechanism. To this end, a second setup is used which is tuned on a nearby but unused frequency. Meteor reflections will only influence the first station (which is tuned to the distant transmitter). On the other hand, peaks which simultaneously ocurr in the signal strength of both setups must be considered as local interference (which is broadbanded).

Principle of Anticoincidence measurement

Results of the observations

This kind of setup typically gives hourly rates of meteor reflections. Obviously, these hour counts can be used for the detection and investigation of meteor showers.

A radio setup can be used during the day as well as during the night, and is not influenced by the presence of clouds. Therefore, it is of great value for long-time monitoring projects, particularly because the system is completely automated.

Some observational results

This picture shows a typical observation of the hourly meteor rate during the period 01/01/95 to 16/01/95. On the 3th of January, enhanced activity, due to the presence of the Bootide meteor shower, is clearly visible. The strong daily variation (with a maximum at 6h UT and a minimum at 18hUT) is called apex effect, and is caused by the rotation of the Earth around the Sun.

Click here to view the actual observations