Very Low Frequency detection of ionospheric disturbances due to GRB 090424

We report the detection of a Gamma Ray Burst GRB 090424 through the Very Low Frequency signal at three receiving stations. Very Low Frequency data recorded corresponding to 18.2 kHz at Salt Lake, ICSP and Malda situated on somewhat different propagation paths. The initial strong burst from GRB 090424 was double peaked followed by two much smaller peaks as observed by gamma ray space observatories. Double peaks are also seen in Very Low Frequency signals. However, because of slower response of the ionosphere the initial strong peaks were not resolved. The second Very Low Frequency peak is correlated to the smaller peaks. All the three VLF receivers got almost the same nature. We verified that there were no other disturbances (e.g. from solar flares) during this period of observation.