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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 230307A: BALROG localization (Fermi Trigger 699896651/ GRB 230307656)
  2. GRB 230307A: AstroSat CZTI detection
  3. GRB 230307A: possibly the second highest GRB energy fluence ever identified
  4. IPN triangulation of GRB 230307A (long/very bright)
  5. GRB 230307A: AGILE/MCAL detection
  6. GRB 230307A: Fermi GBM Observation of a very bright burst
  7. Solar Orbiter STIX observation of GRB 230307A
  8. IceCube-230306A: Upper limits from a search for additional neutrino events in IceCube
  9. Fermi-LAT gamma-ray observations of IceCube-230306A
  10. GRB 230307A: Fermi GBM detection of a very bright GRB
  11. GRB 230307A: GECAM detection of an extremely bright burst
  12. GRB 230307A: Fermi GBM Final Real-time Localization
  13. Fermi trigger No 699811746: Global MASTER-Net observations report
  14. IceCube-230306A - IceCube observation of a high-energy neutrino candidate
  15. IceCube Alert 230306.46: Global MASTER-Net observations report
  16. GRB 230304C: AstroSat CZTI detection
  17. GRB 230304B: AstroSat CZTI detection
  18. GRB 230304A: AstroSat CZTI detection
  19. GRB 230304B: Detection by GRBAlpha
  20. GRB 230304C: Fermi GBM Final Real-time Localization
  21. GRB 230304B: Fermi GBM Final Real-time Localization
  22. GRB 230304A: Fermi GBM Final Real-time Localization
  23. GRB 230228A: 6 GHz VLA radio upper limit
  24. GRB 230228A: Swift-BAT refined analysis
  25. GRB 230228A: Swift/UVOT Upper Limits
  26. Fermi GRB 230301B: Global MASTER-Net observations report
  27. GRB 230301B: Fermi GBM Final Real-time Localization
  28. GRB 230228A: Fermi GBM Observation
  29. Fermi trigger No 699294715: Global MASTER-Net observations report
  30. GRB 230228A: OSN optical upper limit
  31. Fermi trigger No 699311646: Global MASTER-Net observations report
  32. GRB 230301A: Fermi GBM Final Real-time Localization
  33. GRB 230228A: Swift-XRT refined Analysis
  34. GRB 230228A: Mondy optical upper limit
  35. GRB 230228A: Enhanced Swift-XRT position
  36. GRB 230228A: Nanshan/NEXT optical upper limit
  37. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  38. GRB 230228A: Prompt enhanced Swift-XRT position
  39. GRB 230228A: Swift detection of a possibly short burst
  40. Fermi GRB 230227A: Global MASTER-Net observations report
  41. GRB 230227A: Fermi GBM Final Real-time Localization
  42. Fermi trigger No 699029364: Global MASTER-Net observations report
  43. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  44. GRB 230216A Mondy Observations
  45. GRB 230205A: VLA radio afterglow confirmation
  46. IceCube-230220A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 230217A: Swift/UVOT Upper Limits
  48. GRB 230216A: Swift/UVOT Upper Limits
  49. GRB 230217A: Continued Gemini Observations
  50. GRB 230220A: Correction to GCN 33352
  51. GRB 230222A: Fermi GBM Final Real-time Localization
  52. GRB 230217A: Swift-XRT afterglow detection
  53. Fermi-LAT gamma-ray observations of IceCube-230220A
  54. GRB 230217A: Swift-BAT refined analysis
  55. Fermi GRB 230220B: Global MASTER-Net observations report
  56. GRB 230217A: AstroSat CZTI detection
  57. GRB 230217A: Gemini South optical upper limits
  58. GRB 230216B: CALET Gamma-Ray Burst Monitor detection
  59. GRB 230217A: 6 GHz VLA observations
  60. GRB 230220B: Fermi GBM Final Real-time Localization
  61. GRB 230217A: Gemini-South Optical Observation
  62. IceCube-230217A: Upper limits from a search for additional neutrino events in IceCube
  63. IceCube-230220A - IceCube observation of a high-energy neutrino candidate
  64. GRB 230217A: Fermi GBM observation
  65. GRB 230220A: MAXI/GSC detection
  66. IceCube-230217A: BOOTES-4/MET Optical Observations
  67. Fermi-LAT gamma-ray observations of IceCube-230217A
  68. Konus-Wind detection of GRB 230217A
  69. GRB 230217A: Swift-XRT observations
  70. Fermi trigger No 698427992: Global MASTER-Net observations report
  71. IceCube Alert 230217.87: Global MASTER-Net observations report
  72. GRB 230218A is not a GRB
  73. GRB 230218A: Fermi GBM Final Real-time Localization
  74. GRB 230217A: AGILE/MCAL detection
  75. GRB 230207B: CALET Gamma-Ray Burst Monitor detection
  76. GRB 230216B: AstroSat CZTI detection
  77. GRB 230216A: SVOM/C-GFT optical upper limit
  78. GRB 230217A: Swift detection of a short burst
  79. GRB 230217A: Fermi GBM Final Real-time Localization
  80. IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
  81. GRB 230216A: Swift-BAT refined analysis
  82. GRB 230216A: Swift-XRT refined Analysis
  83. GRB 230205A: Lowell Discovery Telescope Observations
  84. GRB 230204B: Lowell Discovery Telescope Observations
  85. Swift GRB 230216A: Global MASTER-Net observations report
  86. GRB 230216A: Enhanced Swift-XRT position
  87. GRB 230216A: AKO Upper Limit
  88. GRB 230216A: Zadko observatory - Gingin optical observations
  89. GRB 230216A: Swift detection of a burst
  90. Fermi GRB 230215A: Global MASTER-Net observations report
  91. GRB 230215A: Fermi GBM Final Real-time Localization
  92. GRB 230209B: AGILE detection
  93. GRB 230209B: Fermi GBM Observation
  94. IPN triangulation of GRB 230209B
  95. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  96. GRB 230204B: ATCA radio detection
  97. Outburst from LS V +44 17 / RX J0440.9+4431: Transient detection by GRBAlpha
  98. Fermi trigger No 697926015: Global MASTER-Net observations report
  99. Fermi trigger No 697904388: Global MASTER-Net observations report
  100. 230211A is not a GRB

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