1. Cosmic rays and Gamma Ray Bursts (GRB’s) Prepared by Brant Carlson, Morris Cohen, and Benjamin Cotts Stanford University, Stanford, CA IHY Workshop on Advancing VLF through the Global AWESOME Network

12. Gamma Rays and the Ionosphere Solar ionization disappears at night Recombination rates on the order of ms Nighttime density maintained by cosmic ray flux

13. Gamma-ray bursts Associated with very energetic explosions  Collapsing star  Supernova formation Typically lasts a few ms to several minutes Accidentally discovered by Vela-3 spacecraft in 1967

14. Gamma-ray waveform Broad variety of durations and shapes

15. Gamma-ray burst on the ionosphere From Fishman et al. 1988

16. Massive gamma-ray burst From Inan et al. 2007

17. Second timescale characteristics From Inan et al. 2007 -25 dB disturbance!! From Inan et al. 2007

18. Minutes timescale characteristic From Inan et al. 1988 Slow recovery

19. Hour timescale characteristic From Inan et al. 2007 Recovery lasts for over 1 hour!

20. ELF emissions generated From Inan et al. 2007 Mechanism for ELF emissions in question….

21. GRBs/SGRs and VLF sensing VLF remote sensing of D-region ionosphere GRBs repeatedly disturb ionosphere

22. NLK: 16-hour observations Largest disturbances

23. NLK: most spectacular cases

24. SGR-Illuminated hemisphere January 22 nd, 2009, 6:48 UT Calculated using http://home.att.net/~srschmitt/script_celestial2horizon.html

25. Sunrise position 0250 UT 0650 UT 1050 UT