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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB 200411A: Enhanced Swift-XRT position
  2. IceCube-200410A: Possible associated excess in INTEGRAL SPI-ACS prompt observation
  3. GRB 200411A: Swift detection of a short burst
  4. GRB 200411A: Fermi GBM Final Real-time Localization
  5. IceCube-200410A - IceCube observation of a high-energy neutrino candidate event
  6. IceCube Alert 200410.97: Global MASTER-Net observations report
  7. GRB 200410A: Swift/UVOT Detection
  8. SGR 1935+2154: Fermi GBM observation
  9. Baksan Neutrino Observatory Alert 200410.82: Global MASTER-Net observations report
  10. Fermi trigger No 608204639: Global MASTER-Net observations report
  11. Baksan Neutrino Observatory Alert 200409.81: Global MASTER-Net observations report
  12. IPN Triangulation of a bright burst from SGR 1935+2154
  13. LIGO/Virgo S200225q: Swift XRT observations, 1 X-ray sources
  14. Konus-Wind observation of GRB 200327A
  15. LIGO/Virgo S200224ca: Swift XRT observations, 8 X-ray sources
  16. GRB 200410A: Swift-XRT refined Analysis
  17. GRB 200410A: Enhanced Swift-XRT position
  18. GRB 200409A: No detection of radio emission 5 hours post-burst
  19. GRB 200410A: Ondrejov D50 afterglow confirmation
  20. GRB 200409A: Swift-BAT refined analysis
  21. GRB 200410A: Swift detection of a burst with a possible optical counterpart
  22. Swift GRB200410.10: Global MASTER-Net observations report
  23. GRB 200405B: ATCA follow-up and ASKAP limits on pre-burst radio emission
  24. Baksan Neutrino Observatory Alert 200408.26: Global MASTER-Net observations report
  25. Fermi GBM Sub-Threshold Detection of GRB 200409A
  26. Baksan Neutrino Observatory Alert 200409.23: Global MASTER-Net observations report
  27. Swift GRB 200409A: Global MASTER-Net observations report
  28. GRB 200409A: Swift-XRT refined Analysis
  29. GRB 200409A: Enhanced Swift-XRT position
  30. GRB 200409A: Swift detection of a burst with an optical counterpart
  31. Fermi GRB 200407A: Global MASTER-Net observations report
  32. Fermi GRB 200407B: Global MASTER-Net observations report
  33. IPN triangulation of GRB 200407A (short)
  34. IPN triangulation of GRB 200405B (short)
  35. Baksan Neutrino Observatory Alert 200406.3: Global MASTER-Net observations report
  36. GRB 200407B: Fermi GBM Final Real-time Localization
  37. GRB 200407A: Fermi GBM Final Real-time Localization
  38. GRB 200405B: LCO Optical Upper Limits
  39. GRB 200405B: Swift-XRT observations
  40. GRB 200405B: Swift ToO observations
  41. Fermi GRB 200405A: Global MASTER-Net observations report
  42. GRB 200405B: Swift/BAT-GUANO detection and *possible* arcminute localization of a short GRB
  43. GRB 200405A: Fermi GBM Final Real-time Localization
  44. GRB 200404A: Fermi GBM Final Localization
  45. Fermi GRB 200403C: Global MASTER-Net observations report
  46. GRB 200404A: BALROG localization (Fermi Trigger 607712227 / GRB 200404706)
  47. GRB 200403A: AstroSat CZTI detection
  48. Fermi GRB 200403B: Global MASTER-Net observations report
  49. Fermi GRB 200403A: Global MASTER-Net observations report
  50. GRB 200403C: Fermi GBM Final Real-time Localization
  51. LIGO/Virgo S200316bj: Upper limits from Konus-Wind observations
  52. LIGO/Virgo S200311bg: Upper limits from Konus-Wind observations
  53. LIGO/Virgo S200302c: Upper limits from Konus-Wind observations
  54. LIGO/Virgo S200225q: Upper limits from Konus-Wind observations
  55. GRB 200403B: Fermi GBM Final Real-time Localization
  56. LIGO/Virgo S200224ca: Upper limits from Konus-Wind observations
  57. GRB 200403A: Fermi GBM Final Real-time Localization
  58. GRB 200325B: Mondy continued observations
  59. Fermi GRB 200402C: Global MASTER-Net observations report
  60. GRB 200402C: Fermi GBM Final Localization
  61. GRB 200402B: Fermi GBM Final Localization
  62. Fermi trigger No 607537834: Global MASTER-Net observations report
  63. GRB 200402B: BALROG localization (Fermi Trigger 607537834 / GRB 200402688)
  64. Fermi GRB 200402A: Global MASTER-Net observations report
  65. GRB 200402A: BALROG localization (Fermi Trigger 607513182 / GRB 200402403)
  66. GRB 200325B: Optical upper limit
  67. GRB 200402A: Fermi GBM Final Real-time Localization
  68. GRB 200325B: further Swift-XRT observations
  69. Fermi GRB 200401A: Global MASTER-Net observations report
  70. GRB 200401A: Fermi GBM Final Real-time Localization
  71. GRB 200325B: Mondy continued observations
  72. GRB 200325B: Mondy continued observations
  73. GRB 200327A: Fermi GBM detection
  74. GRB 200325B: Mondy continued observations
  75. GRB 200325B: Tautenburg observations
  76. IPN triangulation of GRB 200327A (short)
  77. GRB 200326B: AstroSat CZTI detection
  78. GRB 200327A: AGILE/MCAL observations
  79. GRB 200325B: Fermi GBM observation
  80. Fermi trigger No 607035413: Global MASTER-Net observations report
  81. GRB 200327A: Fermi GBM Final Real-time Localization
  82. GRB 200325B: Swift-XRT and UVOT observations
  83. GRB 200325B: LCO Optical Detection
  84. GRB 200325B: Mondy, CrAO, AbAO afterglow confirmation and refined photometry of MASTER OT J111012.51+274912.8
  85. GRB 200326B: AstroSat LAXPC detection
  86. GRB 200325A: Fermi GBM observation
  87. GRB 200325B: Mondy and CrAO observations, Master MASTER OT J111012.51+274912.8 confirmation
  88. Fermi trigger No 606918292: Global MASTER-Net observations report
  89. GRB 200325B: Swift ToO observations
  90. IPN triangulation of GRB 200325A (short)
  91. Fermi trigger No 606799116: Global MASTER-Net observations report
  92. GRB 200326A: Fermi GBM Final Real-time Localization
  93. GRB 200325B: MASTERt OT detection
  94. GRB 200324A: AROMA-N Optical Observation
  95. GRB 200325A: Swift/BAT detection and probable arcminute localization of a short GRB from GUANO
  96. GRB 200324A, Swift-BAT refined analysis
  97. Fermi trigger No 606840801: Global MASTER-Net observations report
  98. GRB 200325B: Fermi GBM Final Real-time Localization
  99. GRB 200324A:: TSHAO optical upper limit
  100. GRB 200324A: Swift/UVOT Upper Limits

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