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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 220508A: Fermi GBM Final Real-time Localization
  2. GRB 220507A: Fermi GBM Final Localization
  3. GRB 220506A: BOOTES-5/JGT optical upper limit
  4. Fermi trigger No 673610950: Global MASTER-Net observations report
  5. GRB 220506A: Swift-XRT afterglow detection
  6. GRB 220506A: Tiled Swift observations
  7. IceCube-220405B - ZTF19aavnpjv unrelated
  8. Swift-BAT triggers 1105560-1 are not GRBs
  9. Swift GRB220506.51: Global MASTER-Net observations report
  10. GRB 220506A/MAXI J1558-266: MAXI/GSC detection
  11. MAXI GRB220506.27: Global MASTER-Net observations report
  12. GRB 220430A: Nanshan/NEXT optical upper limit
  13. GRB 220430A: Nanshan/HMT optical upper limit
  14. GRB 220430A: GIT optical upper limits
  15. IPN triangulation of GRB 220423A
  16. GRB 220427A: LCO Optical Observations
  17. IceCube-220501A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 220501A: Swift-BAT refined analysis
  19. Fermi-LAT Gamma-ray Observations of IceCube-220501A
  20. GRB 220427A: GRANDMA Early Optical Afterglow Detection
  21. GRB 220501A: BOOTES-1 optical upper limit
  22. IceCube-220501A: No Candidate Counterparts from the Zwicky Transient Facility
  23. GRB 220501A: Fermi GBM observation
  24. GRB 220430A: AstroSat CZTI detection
  25. IceCube-220501A - IceCube observation of a high-energy neutrino candidate track-like event
  26. IceCube Alert 220501.95: Global MASTER-Net observations report
  27. GRB 220501A: GRANDMA/TJML Optical Observations
  28. GRB 220501A: Fermi GBM Final Real-time Localization
  29. GRB 220501A: Swift detection of a burst
  30. GRB 220430A: Swift-BAT refined analysis
  31. GRB 220430A: CAHA 2.2m telescope optical limit
  32. GRB 220430A: Swift-XRT refined Analysis
  33. Swift GRB 220430A: Global MASTER-Net observations report
  34. GRB 220430A: GRANDMA observations
  35. GRB 220430A: Mondy and AbAO optical upper limits
  36. GRB 220430A: AGILE detection
  37. GRB 220430A: MeerLICHT optical upper limits
  38. GRB 220430A: Enhanced Swift-XRT position
  39. GRB 220430A: Swift detection of a burst or Swift J0630.4+0932
  40. IceCube-220425A: Upper limits from a search for additional neutrino events in IceCube
  41. IceCube-220424A: Upper limits from a search for additional neutrino events in IceCube
  42. IceCube-220421A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 220427A: Swift-BAT refined analysis
  44. GRB 220427A: VLT/X-shooter photometry
  45. GRB 220426A: Swift-XRT and UVOT observations
  46. GRB 220423A: Detection by VZLUSAT-2
  47. Konus-Wind detection of GRB 220427A
  48. GRB 220427A: Swift-XRT refined Analysis
  49. GRB 220427A: Enhanced Swift-XRT position
  50. GRB 220426A: Tiled Swift observations
  51. GRB 220427A: Swift detection of a burst with an optical counterpart
  52. Konus-Wind detection of GRB 220426A
  53. IPN triangulation of GRB 220426A
  54. GRB 220426C: Swift/BAT-GUANO detection outside the coded FOV (short)
  55. Fermi GRB 220426A: Global MASTER-Net observations report
  56. GRB 220426A: Fermi GBM detection
  57. GRB 220426A: Swift/BAT-GUANO detection outside the coded FOV
  58. Fermi-LAT Gamma-ray Observations of IceCube-220425A
  59. Fermi GRB 220426B: Global MASTER-Net observations report
  60. GRB 220426B: Fermi GBM Final Real-time Localization
  61. GRB 220426A: BALROG localization (Fermi Trigger 672648596/ GRB 220426285)
  62. Correction to 31937: GRB 220421B: Detection by VZLUSAT-2
  63. IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate
  64. Fermi-LAT Gamma-ray Observations of IceCube-220424A
  65. IceCube Alert 220425.11: Global MASTER-Net observations report
  66. Fermi trigger No 672492774: Global MASTER-Net observations report
  67. IceCube-220425A - IceCube observation of a high-energy neutrino candidate track-like event
  68. GRB 220423A: Swift/BAT-GUANO detection outside the coded FOV
  69. IceCube-220424A - IceCube observation of a high-energy neutrino candidate track-like event
  70. IceCube Alert 220424.05: Global MASTER-Net observations report
  71. Fermi trigger No 672374264: Global MASTER-Net observations report
  72. On the AGILE detection of GRB 220423A
  73. GRB 220423A: AGILE detection
  74. GRB 220421B: Detection by VZLUSAT-2
  75. GRB 220421A: Fermi GBM observation
  76. Fermi-LAT Gamma-ray Observations of IceCube-220421A
  77. GRB 220421A: Swift/BAT-GUANO detection outside the coded FOV
  78. Fermi trigger No 672221879: Global MASTER-Net observations report
  79. Fermi GBM trigger 672128054/220420260 is not a GRB
  80. IceCube-220421A - IceCube observation of a high-energy neutrino candidate track-like event
  81. GRB 220418B: Swift-XRT observations
  82. IceCube Alert 220421.22: Global MASTER-Net observations report
  83. GRB 220418B Fermi GBM observation
  84. Fermi trigger No 672093919: Global MASTER-Net observations report
  85. “GRB 220420A” is not a GRB
  86. GRB 220420A: Swift/BAT-GUANO detection outside the coded FOV
  87. GRB 220403C: Further Swift-XRT observations
  88. GRB 220418B: Swift ToO observations
  89. GRB 220417A: Fermi GBM detection
  90. GRB 220418B: Swift/BAT-GUANO refined location of a short burst
  91. IPN triangulation of GRB 220411A
  92. GRB 220418B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  93. GRB 220417A: Swift/BAT-GUANO detection outside the coded FOV
  94. GRB 220412B: Swift/UVOT Upper Limits
  95. Fermi GRB 220418A: Global MASTER-Net observations report
  96. GRB 220418B: Fermi GBM Final Real-time Localization
  97. GRB 220418A: Fermi GBM Final Real-time Localization
  98. Fermi GRB 220417A: Global MASTER-Net observations report
  99. GRB 220417A: Fermi GBM Final Real-time Localization
  100. Fermi trigger No 671729344: Global MASTER-Net observations report

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