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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. IPN triangulation of GRB 230307A (long/very bright)
  2. GRB 230307A: AGILE/MCAL detection
  3. GRB 230307A: Fermi GBM Observation of a very bright burst
  4. Solar Orbiter STIX observation of GRB 230307A
  5. IceCube-230306A: Upper limits from a search for additional neutrino events in IceCube
  6. Fermi-LAT gamma-ray observations of IceCube-230306A
  7. GRB 230307A: Fermi GBM detection of a very bright GRB
  8. GRB 230307A: GECAM detection of an extremely bright burst
  9. GRB 230307A: Fermi GBM Final Real-time Localization
  10. Fermi trigger No 699811746: Global MASTER-Net observations report
  11. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  12. IceCube Alert 230306.46: Global MASTER-Net observations report
  13. GRB 230304C: AstroSat CZTI detection
  14. GRB 230304B: AstroSat CZTI detection
  15. GRB 230304A: AstroSat CZTI detection
  16. GRB 230304B: Detection by GRBAlpha
  17. GRB 230304C: Fermi GBM Final Real-time Localization
  18. GRB 230304B: Fermi GBM Final Real-time Localization
  19. GRB 230304A: Fermi GBM Final Real-time Localization
  20. GRB 230228A: 6 GHz VLA radio upper limit
  21. GRB 230228A: Swift-BAT refined analysis
  22. GRB 230228A: Swift/UVOT Upper Limits
  23. Fermi GRB 230301B: Global MASTER-Net observations report
  24. GRB 230301B: Fermi GBM Final Real-time Localization
  25. GRB 230228A: Fermi GBM Observation
  26. Fermi trigger No 699294715: Global MASTER-Net observations report
  27. GRB 230228A: OSN optical upper limit
  28. Fermi trigger No 699311646: Global MASTER-Net observations report
  29. GRB 230301A: Fermi GBM Final Real-time Localization
  30. GRB 230228A: Swift-XRT refined Analysis
  31. GRB 230228A: Mondy optical upper limit
  32. GRB 230228A: Enhanced Swift-XRT position
  33. GRB 230228A: Nanshan/NEXT optical upper limit
  34. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  35. GRB 230228A: Prompt enhanced Swift-XRT position
  36. GRB 230228A: Swift detection of a possibly short burst
  37. Fermi GRB 230227A: Global MASTER-Net observations report
  38. GRB 230227A: Fermi GBM Final Real-time Localization
  39. Fermi trigger No 699029364: Global MASTER-Net observations report
  40. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  41. GRB 230216A Mondy Observations
  42. GRB 230205A: VLA radio afterglow confirmation
  43. IceCube-230220A: Upper limits from a search for additional neutrino events in IceCube
  44. GRB 230217A: Swift/UVOT Upper Limits
  45. GRB 230216A: Swift/UVOT Upper Limits
  46. GRB 230217A: Continued Gemini Observations
  47. GRB 230220A: Correction to GCN 33352
  48. GRB 230222A: Fermi GBM Final Real-time Localization
  49. GRB 230217A: Swift-XRT afterglow detection
  50. Fermi-LAT gamma-ray observations of IceCube-230220A
  51. GRB 230217A: Swift-BAT refined analysis
  52. Fermi GRB 230220B: Global MASTER-Net observations report
  53. GRB 230217A: AstroSat CZTI detection
  54. GRB 230217A: Gemini South optical upper limits
  55. GRB 230216B: CALET Gamma-Ray Burst Monitor detection
  56. GRB 230217A: 6 GHz VLA observations
  57. GRB 230220B: Fermi GBM Final Real-time Localization
  58. GRB 230217A: Gemini-South Optical Observation
  59. IceCube-230217A: Upper limits from a search for additional neutrino events in IceCube
  60. IceCube-230220A - IceCube observation of a high-energy neutrino candidate
  61. GRB 230217A: Fermi GBM observation
  62. GRB 230220A: MAXI/GSC detection
  63. IceCube-230217A: BOOTES-4/MET Optical Observations
  64. Fermi-LAT gamma-ray observations of IceCube-230217A
  65. Konus-Wind detection of GRB 230217A
  66. GRB 230217A: Swift-XRT observations
  67. Fermi trigger No 698427992: Global MASTER-Net observations report
  68. IceCube Alert 230217.87: Global MASTER-Net observations report
  69. GRB 230218A is not a GRB
  70. GRB 230218A: Fermi GBM Final Real-time Localization
  71. GRB 230217A: AGILE/MCAL detection
  72. GRB 230207B: CALET Gamma-Ray Burst Monitor detection
  73. GRB 230216B: AstroSat CZTI detection
  74. GRB 230216A: SVOM/C-GFT optical upper limit
  75. GRB 230217A: Swift detection of a short burst
  76. GRB 230217A: Fermi GBM Final Real-time Localization
  77. IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
  78. GRB 230216A: Swift-BAT refined analysis
  79. GRB 230216A: Swift-XRT refined Analysis
  80. GRB 230205A: Lowell Discovery Telescope Observations
  81. GRB 230204B: Lowell Discovery Telescope Observations
  82. Swift GRB 230216A: Global MASTER-Net observations report
  83. GRB 230216A: Enhanced Swift-XRT position
  84. GRB 230216A: AKO Upper Limit
  85. GRB 230216A: Zadko observatory - Gingin optical observations
  86. GRB 230216A: Swift detection of a burst
  87. Fermi GRB 230215A: Global MASTER-Net observations report
  88. GRB 230215A: Fermi GBM Final Real-time Localization
  89. GRB 230209B: AGILE detection
  90. GRB 230209B: Fermi GBM Observation
  91. IPN triangulation of GRB 230209B
  92. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  93. GRB 230204B: ATCA radio detection
  94. Outburst from LS V +44 17 / RX J0440.9+4431: Transient detection by GRBAlpha
  95. Fermi trigger No 697926015: Global MASTER-Net observations report
  96. Fermi trigger No 697904388: Global MASTER-Net observations report
  97. 230211A is not a GRB
  98. GRB 230211A: Fermi GBM Final Real-time Localization
  99. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  100. Fermi trigger No 697678542: Global MASTER-Net observations report

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