An Unusual Burst at Decameter Wavelengths. 1. Observations

An unusual burst was observed by the UTR-2 (Kharkiv, Ukraine) and URAN-2 (Poltava, Ukraine) radio telescopes on June 3, 2011. It was recorded in the frequency band 16-28 MHz. Its frequency drift rate (about 500 kHz/s) was positive at frequencies higher than 22 MHz and negative with drift rate 100 kHz/s at lower frequencies. The half-power duration of this burst was about the same at all frequencies and made 17-22 s. The fine frequency-time structure was unusual too. The maximum radio flux of the unusual burst at 24 MHz was about 103 s.f.u. and its polarization was about 10 %. We propose an interpretation of the unusual burst.