Tanaka, Y. TRaulin, Jean-PierreBertoni, Fernando C. P.Fagundes, P. R.Chau Chong Shing, Jorge LuisSchuch, N. JHayakawa, M.Hobara, Y.Terasawa, T.Takahashi, T.2018-06-262018-06-262010-08Tanaka, Y. T., Raulin, J. -P., Bertoni, F. C. P., Fagundes, P. R., Chau, J. L., Schuch, N. J., ... Takahashi, T. (2010). First very low frequency detection of short repeated burstds from MAGNETAR SGR J1550−5418.==$The Astrophysical Journal Letters, 721$==(1), L24-L27. https://doi.org/10.1088/2041-8205/721/1/L24index-oti2018http://hdl.handle.net/20.500.12816/1551We report on the first detection of ionospheric disturbances caused by short repeated gamma-ray bursts from the magnetar SGR J1550−5418. Very low frequency (VLF) radio wave data obtained in South America clearly show sudden amplitude and phase changes at the corresponding times of eight soft gamma-ray repeater bursts. Maximum amplitude and phase changes of the VLF signals appear to be correlated with the gamma-ray fluence. On the other hand, VLF recovery timescales do not show any significant correlation with the fluence, possibly suggesting that the bursts’ spectra are not similar to each other. In summary, Earth’s ionosphere can be used as a very large gamma-ray detector and the VLF observations provide us wit.application/pdfenginfo:eu-repo/semantics/restrictedAccessSudden ionospheric disturbancesGamma ray eruptionsVLF radio wave propagationGamma ray spectrometryinfo:eu-repo/semantics/articlehttp://purl.org/pe-repo/ocde/ford#1.05.01The Astrophysical Journal Lettershttps://doi.org/10.1088/2041-8205/721/1/L24