  In this paper, we study the possibility of detection of short term
terrestrial lower ionospheric response to gamma ray bursts (GRBs) using a
statistical analysis of perturbations of six very low or low frequency (VLF/LF)
radio signals emitted by transmitters located worldwide and recorded by VLF/LF
receiver located in Belgrade (Serbia). We consider a sample of 54 short lasting
GRBs (shorter than 1 min) detected by the SWIFT satellite during the period
2009-2012. We find that a statistically significant perturbations can be
present in the low ionosphere, and reactions on GRBs may be observed
immediately after the beginning of the GRB event or with a time delay of 60 s -
90 s.

Space Physics