617 Russian Physics Journal, Vol. 50, No. 6, 2007 OBSERVATION OF SIGNALS OF VLF RADIO STATIONS AND VLF NOISE DURING THE SOLAR ECLIPSE ON MARCH 29, 2006. V. I. Kozlov, R. R. Karimov, and V. A. Mullayarov UDC 550.388 Effects of the solar eclipse on March 29, 2006 on signals of VLF radio stations, regular radio-noise intensity in the VLF range 0.3–10 kHz, and the number of atmospherics registered in Yakutsk mainly from the western direction are considered. The full lunar shadow zone consistently shaded the daytime section of the radio-signal propagation path from the western coast of Africa to Altai. A multichannel parallel analyzer-recorder (operating in the frequency range 0.47–8.7 kHz), one-point thunderstorm direction-and-range finder (0.3–100 kHz), narrow-sector radio-noise direction finder (0.3–10 kHz), recorder of VLF radio-station signals, and broadband radio-noise recorder (0.3–100 кГц) were used for observations. Time synchronization of the recorder of VLF radio-station signals was carried out with the help of GPS-clocks. The effect was observed in radio-station signals, radio-noise, and number of atmospherics from a direction of (270 ± 20)º, counted from the north clockwise, in the last stage of the eclipse (~11–12 UT), when the lunar shadow approached the night terminator and crossed the signal propagation path. The effect was manifested through a ~20% gain of the received signals, ~40% increase in the number of atmospherics, and radio-station phase changes. The registered effects are similar to those we observed during the eclipse on March 9, 1997. INTRODUCTION The full lunar shadow zone during the solar eclipse on March 29, 2006 consistently shadowed the daytime section of the radio-signal propagation path from the western coast of Africa to Altai. The effects of eclipses on March 29, 2006 and March 9, 1997 on the radio-signal propagation paths differ by the fact that on March 29, 2006 the receiving point in Yakutsk was on the night side, and the main sources of selected radio- noise were on the African continent in the daytime conditions, whereas on March 9, 1997, on the contrary, the main sources of VLF radio noise, selected with the help of antenna patterns and methodically, were on the night side, and the observation point was on the daytime side. The full lunar shadow zone shadowed a section of the daytime radio-signal propagation path. Thus, these two observations supplement each other. The effects on signals of VLF radio stations, regular radio-noise intensity in the frequency range 0.3–10 kHz, and numbers of atmospherics registered in Yakutsk mainly from the western direction are considered. TECHNIQUE AND RESULTS Observations were performed with a multichannel analog parallel analyzer-recorder (operating in the frequency range 0.47–8.7 kHz) [1], single-point thunderstorm direction-and-range finder (0.3–100 kHz) [2], narrow-sector direction finder of radio-noise (0.3–10 kHz) [3], recorder of signals of VLF radio stations, and broadband radio-noise recorder (0.3– 100 kHz) [4]. With the help of the last recorder, synoptic recording was carried out. Time synchronization of the recorder of signals of VLF radio stations was carried out with the help of GPS-clocks (Thunderbolt). Figure 1 shows the radio-noise intensities received in Yakutsk by a frame magnetic antenna oriented in the E–W direction on the day of the solar eclipse (March 29, 2006) and the next day (March 30, 2006). Institute of Cosmophysical Investigations and Aeronomy of the Siberian Branch of the Russian Academy of Sciences, e-mail: v.kozlov@ikfia.ysn.ru, karimov@ikfia.ysn.ru, mullayarov@ikfia.ysn.ru. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 84–87, June, 2007. Original article submitted December 11, 2006. 1064-8887/07/5006-0617 ©2007 Springer Science+Business Media, Inc.