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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. IceCube-230306A: Upper limits from a search for additional neutrino events in IceCube
  2. Fermi-LAT gamma-ray observations of IceCube-230306A
  3. GRB 230307A: Fermi GBM detection of a very bright GRB
  4. GRB 230307A: GECAM detection of an extremely bright burst
  5. GRB 230307A: Fermi GBM Final Real-time Localization
  6. Fermi trigger No 699811746: Global MASTER-Net observations report
  7. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  8. IceCube Alert 230306.46: Global MASTER-Net observations report
  9. GRB 230304C: AstroSat CZTI detection
  10. GRB 230304B: AstroSat CZTI detection
  11. GRB 230304A: AstroSat CZTI detection
  12. GRB 230304B: Detection by GRBAlpha
  13. GRB 230304C: Fermi GBM Final Real-time Localization
  14. GRB 230304B: Fermi GBM Final Real-time Localization
  15. GRB 230304A: Fermi GBM Final Real-time Localization
  16. GRB 230228A: 6 GHz VLA radio upper limit
  17. GRB 230228A: Swift-BAT refined analysis
  18. GRB 230228A: Swift/UVOT Upper Limits
  19. Fermi GRB 230301B: Global MASTER-Net observations report
  20. GRB 230301B: Fermi GBM Final Real-time Localization
  21. GRB 230228A: Fermi GBM Observation
  22. Fermi trigger No 699294715: Global MASTER-Net observations report
  23. GRB 230228A: OSN optical upper limit
  24. Fermi trigger No 699311646: Global MASTER-Net observations report
  25. GRB 230301A: Fermi GBM Final Real-time Localization
  26. GRB 230228A: Swift-XRT refined Analysis
  27. GRB 230228A: Mondy optical upper limit
  28. GRB 230228A: Enhanced Swift-XRT position
  29. GRB 230228A: Nanshan/NEXT optical upper limit
  30. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  31. GRB 230228A: Prompt enhanced Swift-XRT position
  32. GRB 230228A: Swift detection of a possibly short burst
  33. Fermi GRB 230227A: Global MASTER-Net observations report
  34. GRB 230227A: Fermi GBM Final Real-time Localization
  35. Fermi trigger No 699029364: Global MASTER-Net observations report
  36. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  37. GRB 230216A Mondy Observations
  38. GRB 230205A: VLA radio afterglow confirmation
  39. IceCube-230220A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 230217A: Swift/UVOT Upper Limits
  41. GRB 230216A: Swift/UVOT Upper Limits
  42. GRB 230217A: Continued Gemini Observations
  43. GRB 230220A: Correction to GCN 33352
  44. GRB 230222A: Fermi GBM Final Real-time Localization
  45. GRB 230217A: Swift-XRT afterglow detection
  46. Fermi-LAT gamma-ray observations of IceCube-230220A
  47. GRB 230217A: Swift-BAT refined analysis
  48. Fermi GRB 230220B: Global MASTER-Net observations report
  49. GRB 230217A: AstroSat CZTI detection
  50. GRB 230217A: Gemini South optical upper limits
  51. GRB 230216B: CALET Gamma-Ray Burst Monitor detection
  52. GRB 230217A: 6 GHz VLA observations
  53. GRB 230220B: Fermi GBM Final Real-time Localization
  54. GRB 230217A: Gemini-South Optical Observation
  55. IceCube-230217A: Upper limits from a search for additional neutrino events in IceCube
  56. IceCube-230220A - IceCube observation of a high-energy neutrino candidate
  57. GRB 230217A: Fermi GBM observation
  58. GRB 230220A: MAXI/GSC detection
  59. IceCube-230217A: BOOTES-4/MET Optical Observations
  60. Fermi-LAT gamma-ray observations of IceCube-230217A
  61. Konus-Wind detection of GRB 230217A
  62. GRB 230217A: Swift-XRT observations
  63. Fermi trigger No 698427992: Global MASTER-Net observations report
  64. IceCube Alert 230217.87: Global MASTER-Net observations report
  65. GRB 230218A is not a GRB
  66. GRB 230218A: Fermi GBM Final Real-time Localization
  67. GRB 230217A: AGILE/MCAL detection
  68. GRB 230207B: CALET Gamma-Ray Burst Monitor detection
  69. GRB 230216B: AstroSat CZTI detection
  70. GRB 230216A: SVOM/C-GFT optical upper limit
  71. GRB 230217A: Swift detection of a short burst
  72. GRB 230217A: Fermi GBM Final Real-time Localization
  73. IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
  74. GRB 230216A: Swift-BAT refined analysis
  75. GRB 230216A: Swift-XRT refined Analysis
  76. GRB 230205A: Lowell Discovery Telescope Observations
  77. GRB 230204B: Lowell Discovery Telescope Observations
  78. Swift GRB 230216A: Global MASTER-Net observations report
  79. GRB 230216A: Enhanced Swift-XRT position
  80. GRB 230216A: AKO Upper Limit
  81. GRB 230216A: Zadko observatory - Gingin optical observations
  82. GRB 230216A: Swift detection of a burst
  83. Fermi GRB 230215A: Global MASTER-Net observations report
  84. GRB 230215A: Fermi GBM Final Real-time Localization
  85. GRB 230209B: AGILE detection
  86. GRB 230209B: Fermi GBM Observation
  87. IPN triangulation of GRB 230209B
  88. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  89. GRB 230204B: ATCA radio detection
  90. Outburst from LS V +44 17 / RX J0440.9+4431: Transient detection by GRBAlpha
  91. Fermi trigger No 697926015: Global MASTER-Net observations report
  92. Fermi trigger No 697904388: Global MASTER-Net observations report
  93. 230211A is not a GRB
  94. GRB 230211A: Fermi GBM Final Real-time Localization
  95. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  96. Fermi trigger No 697678542: Global MASTER-Net observations report
  97. Swift Trigger 1153670 is probably not a GRB
  98. GRB 230210A: Fermi GBM Final Real-time Localization
  99. Fermi GRB 230209B: Global MASTER-Net observations report
  100. GRB 230209B: Fermi GBM Final Real-time Localization

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