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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"

11533 results found.

  1. Fermi Gamma-ray Burst Monitor trigger 736837160/240508208 is not a GRB
  2. Fermi trigger No 736733320: Global MASTER-Net observations report
  3. IPN triangulation of GRB 240504A
  4. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  5. Fermi GBM triggers 736668287/240506253 and 736669277/240506265 are not GRBs
  6. Fermi trigger No 736564880: Global MASTER-Net observations report
  7. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  8. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  9. Fermi trigger No 736461232: Global MASTER-Net observations report
  10. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  11. Fermi GRB 240504A: Global MASTER-Net observations report
  12. Fermi trigger No 736472503: Global MASTER-Net observations report
  13. GRB 240504A: BALROG localization (Fermi Trigger 736492377 / GRB 240504217)
  14. GRB 240504A: Fermi GBM Final Real-time Localization
  15. Fermi trigger No 736387941: Global MASTER-Net observations report
  16. GRB 240502A: GOTO optical upper limit
  17. Fermi trigger No 736379109: Global MASTER-Net observations report
  18. GRB 240502A: Fermi GBM Observation
  19. GRB 240502C: GOTO possible optical counterpart candidates
  20. Fermi GRB 240502B: Global MASTER-Net observations report
  21. GRB 240502C: Fermi GBM Final Localization
  22. Fermi GRB 240502A: Global MASTER-Net observations report
  23. GRB 240430A: GRBAlpha detection
  24. GRB 240502B: Fermi GBM Final Real-time Localization
  25. GRB 240502A: Fermi GBM Final Real-time Localization
  26. Fermi GRB 240501A: Global MASTER-Net observations report
  27. Fermi trigger No 736197684: Global MASTER-Net observations report
  28. GRB 240425A: VZLUSAT-2 detection
  29. GRB240430A: Fermi GBM Final Localization
  30. GRB 240501A: Fermi GBM Final Real-time Localization
  31. GRB 240407A: VZLUSAT-2 detection
  32. GRB 240425A: GRBAlpha detection
  33. Fermi-LAT gamma-ray observations of IceCube-240424A
  34. GRB 240429A: Fermi GBM Final Real-time Localization
  35. Fermi GRB 240428A: Global MASTER-Net observations report
  36. GRB 240428A: Fermi GBM Final Real-time Localization
  37. GRB 240425A: Fermi GBM Final Real-time Localization
  38. Fermi trigger No 735697285: Global MASTER-Net observations report
  39. GRB 240422A: Glowbug gamma-ray detection
  40. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 240421B: GRBAlpha detection
  42. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  43. Fermi trigger No 735470374: Global MASTER-Net observations report
  44. GRB 240421A: Glowbug gamma-ray detection
  45. GRB 240414A: radio detection with the VLA
  46. Fermi-LAT gamma-ray observations of IceCube-240419A
  47. Fermi GRB 240422A: Global MASTER-Net observations report
  48. GRB 240421B: AstroSat CZTI detection
  49. GRB 240422A: Fermi GBM Final Real-time Localization
  50. Fermi GRB 240421B: Global MASTER-Net observations report
  51. GRB 240421B: Fermi GBM Observation
  52. Fermi GRB 240421A: Global MASTER-Net observations report
  53. GRB 240421A: Fermi GBM Final Real-time Localization
  54. Fermi trigger No 735280430: Global MASTER-Net observations report
  55. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  56. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  57. Fermi trigger No 735089036: Global MASTER-Net observations report
  58. GRB 240411A: GOTO early optical upper limits
  59. Fermi GRB 240417A: Global MASTER-Net observations report
  60. Improved IPN triangulation of GRB 240411A
  61. GRB 240417A: Fermi GBM Final Real-time Localization
  62. GRB 240415A: Glowbug gamma-ray detection
  63. GRB 240414A: Glowbug gamma-ray detection
  64. GRB 240411A: Glowbug gamma-ray detection
  65. GRB 240415A: Fermi GBM Observation
  66. GRB 240415A: Earliest optical followup with the Kinder observations
  67. GRB 240415A: OHP/T193 optical observations
  68. GRB 240415A: optical afterglow detection from the INAF Asiago Observatory
  69. GRB 240415A: SAO RAS optical observations
  70. GRB 240414A: Fermi GBM Observation
  71. Fermi GRB 240415A: Global MASTER-Net observations report
  72. GRB 240415A: Mondy optical transient detection
  73. GRB 240414B: Fermi GBM Final Real-time Localization
  74. GRB 240415A: Swift detection of a burst
  75. GRB 240415A: Fermi GBM Final Real-time Localization
  76. Fermi trigger No 734754044: Global MASTER-Net observations report
  77. IPN triangulation of GRB 240411A
  78. Fermi-LAT gamma-ray observations of IceCube-240412A
  79. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  80. GRB 240411A: GRBAlpha detection
  81. GRB 240405A: Glowbug gamma-ray detection
  82. GRB 240411A: Fermi GBM Final Real-time Localization
  83. GRB 240405A: GRBAlpha detection
  84. Fermi GRB 240408A: Global MASTER-Net observations report
  85. GRB 240408A: Fermi GBM Final Real-time Localization
  86. GRB 240407A: BALROG localization (Fermi Trigger 734144396 / GRB 240407042)
  87. Fermi GRB 240407A: Global MASTER-Net observations report
  88. GRB 240407A: Fermi GBM Final Real-time Localization
  89. Fermi-LAT gamma-ray observations of IceCube-240327B
  90. Fermi-LAT gamma-ray observations of IceCube-240327A
  91. Fermi GRB 240405B: Global MASTER-Net observations report
  92. GRB 240405B: Fermi GBM Final Real-time Localization
  93. GRB 240405A: Fermi GBM Final Real-time Localization
  94. GRB 240331A: GRBAlpha detection
  95. GRB 240403B: Glowbug gamma-ray detection
  96. GRB 240403A: Glowbug gamma-ray detection
  97. GRB 240403A: Fermi GBM Detection
  98. Fermi GRB 240404A: Global MASTER-Net observations report
  99. GRB 240404A: Fermi GBM Final Real-time Localization
  100. GRB 240403A: BALROG localization (Fermi Trigger 733838255 / GRB 240403498)

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