{
  "bibcode": "2022GCN.32744....1S",
  "body": "P.W. Schnoor (Kiel Longwave Monitor, Germany), P. Nicholson\n(Todmorden, UK), D.L. Welch (McMaster University, Canada)\n\nA sudden disturbance of the Earth's ionosphere (SID) was observed by the\nKiel Longwave Monitor (Germany) and a VLF-Monitor at Todmorden (near\nManchester, UK) coincident with the detection of GRB221009A (SWIFT, \n#32635).\n\nThis SID was seen as a sudden increase or decrease in the signal strengths\nfrom radio transmitters below 100 kHz (19.6 to 63.9 kHz; VLF/LF) received\nat Kiel and Todmorden.\n\nThese naval transmitting stations are located at France, Germany, Iceland,\nIsrael, Italy, Japan (Okinawa), United Kingdom and United States.\n\nNote: This is not a radio detection of GRB221009A; this disturbance was\ncaused by the prompt X-rays and/or gamma-rays from GRB221009A\nionizing the upper atmosphere and modifying the radio propagation\nproperties of the waveguide between ground and ionosphere.\n\nAccording to the SWIFT-BAT refined analysis (RA, Dec = 288.254, 19.809 deg,\nGCN #32688) GRB221009A was above local horizon at both receiving sites\n(2022-10-09, 13:16:59 UT).\n\nKiel:���������� az = 101.8, el = 32.9 deg\nTodmorden: az = 94.6,�� el = 28.3 deg\n\nPlots of the SID detection are available at the following URLs:\n\nKiel\nhttps://www.qsl.net/df3lp/grb221009/KLM_grb221009a_magnitudes.png\n\nTodmorden\nhttp://abelian.org/vlf/grb221009a-DHO.png\nhttp://abelian.org/vlf/grb221009a-NAA.png\nhttp://abelian.org/vlf/grb221009a-NSY.png\n\nThe Kiel Longwave Monitor consists of a set of very low frequency radio\nreceivers attached to a crossed pair of loop antennas (16m^2 each),\nmonitoring the radio spectrum from 1.0 to 96.0 kHz at 50Hz-steps.\n\nThe VLF-monitor at Todmorden consists of a set of very low frequency radio\nreceivers attached to a crossed pair of loop antennas (20m^2 each) and a\nvertical antenna, monitoring the radio spectrum below 100 kHz.",
  "circularId": 32744,
  "createdOn": 1665697347000,
  "email": "welch@physics.mcmaster.ca",
  "subject": "GRB221009A: Detection as sudden ionospheric disturbances (SID)",
  "submitter": "Doug Welch at McMaster University  <welch@physics.mcmaster.ca>",
  "eventId": "GRB 221009A"
}