Some Results of Radar Observations of Meteors in Tomsk during 1957–1959

E. I. Fialko, F. I. Peregudov, E. K. Nemirova, L. P. Serafinovich,
L. A. Pokrovskii, I. D. Zolotarev, G. S. Zubarev

(Presented by the scientific seminar of the Radio Engineering Faculty)

Systematic observations of meteors in Tomsk began in July 1957. The observations were carried out with the aid of the special radio installation “TPI-2.” The transmitter of the “TPI-2” radar operates in pulsed mode at a frequency of 30 MHz. The pulse repetition frequency is 600 pulses/sec. For unambiguous determination of slant range above 250 km and to improve the noise immunity of the system, every second pulse is made double. The pulse duration is 5 μsec. The transmitter power is about 100 kW per pulse. The emission of radio pulses and reception of the reflected signals are performed with nondirectional antennas—half-wave dipoles located at a height of \(\lambda/3\) above the ground surface. The sensitivity of the receivers of the range and angle channels is about \(5 \cdot 10^{-14}\) W. Reflections from meteors are recorded on motion-picture film. In the range finder, recording is carried out on uniformly moving film (film transport speed about 3 cm/min), while in the angle finder frame-by-frame photography of the reflected signals is used.

Fig. 1. Distribution of the parameter \(s\), constructed on the basis of the distribution by duration of 20,000 echoes.

The variation in the number of meteors was investigated for both streams and the sporadic background.

In 1957, about 600 hours of observations were carried out and more than 130,000 reflections were recorded. In 1958, during 1,240 hours, 191,500 reflections were recorded.

In the first half of 1959 (600 hours), about 90,000 reflections from meteor trails were recorded.

It should be noted that about 15% of the reflections have a duration \(\tau \ge 1\) sec.

The material obtained has been partially processed.

The material obtained in 1957 has been almost completely processed. Principal attention was devoted to the systematic determination

Fig. 2. Course of the level of external interference on June 22, 1959
(Tomsk).

Fig. 3. Course of the level of external interference in the presence of a thunderstorm,
July 10, 1959 (Tomsk).

of the exponent \(s\), characterizing the distribution of meteor bodies by mass. The exponent \(s\) was found for meteors of the Perseid stream [1], and it is in satisfactory agreement with data obtained by other researchers [2].

A distribution was constructed by duration for several tens of thousands of echoes with duration \(\tau \ge 1\) sec. On the basis of these experimental data, the distribution of the exponent \(s\) for sporadic meteors was found, which differed little from the known

Fig. 4. Mean variation of external interference for the region of the city of Tomsk.

Observation 15, 16, 17;
total time 1
\(N_{\Sigma}=82\)
\(\bar h=90\ \text{km}\)

Fig. 5. Distribution of meteor heights according to the results of the observations of December 15, 16, 17, and 19, 1958. \(N_{\Sigma}=82.\ \bar h=90\ \text{km}.\)

values \(s \simeq 2\) [2]. Figure 1 gives the differential distribution law of \(s\) [3].

Of considerable interest are data on the distribution of time intervals between reflected signals.

Such a distribution was constructed for meteors recorded during the 1957 Perseid epoch (from 9 to 15 August) [4].

The distribution has an exponential character and confirms the known results obtained in England and the USA [5, 6].

Monitoring of the level of external interference was introduced; its recording began in June 1959. From the monitoring data on the level of external interference, corrections for noise may be introduced into the change in the number of reflections from meteors over the course of a day [7].

Recording of the level of external interference was carried out with a non-directional antenna. Figure 2 shows the change in the level of external interference on 22 June 1959. However, such a change in the interference level in the region of the city of Tomsk is observed very rarely, since atmospheric and industrial interference is superimposed on interference of cosmic origin, sharply changing the course of the level of external interference (Fig. 3).

According to the summer observations, the mean interference level at the radio-engineering test site in the region of Tomsk was obtained (Fig. 4).

In the graph, the solid line depicts the lowest observed level of interference. It is apparently determined only by interference of cosmic origin.

In the same graph, the dotted line represents the most frequently observed course of the level of external interference.

Fig. 6. Distribution of meteor heights (Quadrantid epoch; observations of 4, 5, 6 January 1959).
\(N_\Sigma = 158,\ h = 95\ \text{km}\).

The material on determining meteor heights during the Geminid (1958) and Quadrantid (1959) epochs has been partially processed. From the distribution of meteor heights (Figs. 5, 6), the mean heights of meteor reflections were found for the Geminid epoch (\(h = 90\ \text{km}\)) and the Quadrantid epoch (\(h = 95\ \text{km}\)).

REFERENCES

1. E. I. Fialko. Radar observations of the Perseids in 1957, Astron. Zhurn., 36, no. 2, p. 311, 1959.

2. A. C. B. Lovell. Meteor Astronomy, Oxford, 1954.

3. E. I. Fialko. Some results of a study of the distribution of meteoric bodies by mass, Astron. Tsirk., No. 195, p. 22, 1958.

4. E. I. Fialko. Some statistical characteristics of meteor radio echoes, Bulletin of the Commission on Comets and Meteors of the Astronomical Council of the Academy of Sciences of the USSR, No. 4, p. 9, 1959.

5. L. R. Wylie, H. T. Castillo. Ohio J. Sci., 6, p. 339, 1956.

6. C. A. Ised. Marconi Rev., 17, p. 37, 1954.

7. E. I. Fialko, L. P. Serafinovich. On the influence of the intensity of cosmic interference on the hourly number of meteors detected by radio means, Izvestiya TPI, vol. 105, 28, 1958.