@Article{RaulinTroCasCorMac:2014:NiSeIo,
               author = "Raulin, Jean Pierre and Trottet, Gerard and Castro, Carlos 
                         Guillermo Gimenez de and Correia, Emilia and Macotela, Edith 
                         Liliana",
          affiliation = "{Universidade Presbiteriana Mackenzie} and {Observatoire de Paris} 
                         and {Universidade Presbiteriana Mackenzie} and {Instituto Nacional 
                         de Pesquisas Espaciais (INPE)} and {Universidade Presbiteriana 
                         Mackenzie}",
                title = "Nighttime Sensitivity of Ionospheric VLF Measurements to X-ray 
                         Bursts From a Remote Cosmic Source",
              journal = "Journal of Geophysical Research: Space Physics",
                 year = "2014",
               volume = "119",
                pages = "4758--4766",
             keywords = "VLF waves, High energy, X-ray, SGR, GRB.",
             abstract = "On 22 January 2009, a series of X-ray bursts were emitted by the 
                         soft gamma ray repeater SGR J1550-5418. Some of these bursts 
                         produced enhanced ionization in the nighttime lower ionosphere. 
                         These ionospheric disturbances were studied using X-ray 
                         measurements from the Anti-Coincidence Shield of the Spectrometer 
                         for Integral onboard the International Gamma-Ray Astrophysics 
                         Laboratory and simultaneous phase and amplitude records from two 
                         VLF propagation paths between the transmitter Naval Radio Station, 
                         Pearl Harbor (Hawaii) and the receivers Radio Observatorio do 
                         Itapetinga (Brazil) and Esta{\c{c}}{\~a}o Antarctica Commandante 
                         Ferraz (Antarctic Peninsula). The VLF measurements have been 
                         obtained with an unprecedented high time resolution of 20 ms. We 
                         find that the illumination factor I (illuminated path length times 
                         the cosine of the zenith angle), which characterizes the 
                         propagation paths underlying the flaring object, is a key 
                         parameter which determines the sensitivity threshold of the VLF 
                         detection of X-ray bursts from nonsolar transients. For the 
                         present VLF measurements of bursts from SGR J1550-5418, it is 
                         found that for I\≥1.8 Mm, all X-ray bursts with fluence in 
                         the 25 keV to 2 MeV range larger than F25_min~ 1.0 × 106 erg/cm2 
                         produce a measurable ionospheric disturbance. Such a lower limit 
                         of the X-ray fluence value indicates that moderate X-ray bursts, 
                         as opposed to giant X-ray bursts, do produce ionospheric 
                         disturbances larger than the sensitivity limit of the VLF 
                         technique. Therefore, the frequency of detection of such events 
                         could be improved, for example by increasing the coverage of 
                         existing VLF receiving networks. The VLF detection of high-energy 
                         astrophysical bursts then appears as an important observational 
                         diagnostic to complement their detection in space. This would be 
                         especially important when space observations suffer from adverse 
                         conditions, like saturation, occultation from the Earth, or the 
                         passage of the spacecraft through the South Atlantic anomaly.",
                  doi = "10.1002/2013JA019670",
                  url = "http://dx.doi.org/10.1002/2013JA019670",
                 issn = "2169-9402",
                label = "lattes: 1272123236892781 4 RaulinTroGimCorMac:2014:NiSeIo",
             language = "en",
        urlaccessdate = "27 abr. 2024"
}