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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. Swift GRB 220430A: Global MASTER-Net observations report
  2. GRB 220430A: GRANDMA observations
  3. GRB 220430A: Mondy and AbAO optical upper limits
  4. GRB 220430A: AGILE detection
  5. GRB 220430A: MeerLICHT optical upper limits
  6. GRB 220430A: Enhanced Swift-XRT position
  7. GRB 220430A: Swift detection of a burst or Swift J0630.4+0932
  8. IceCube-220425A: Upper limits from a search for additional neutrino events in IceCube
  9. IceCube-220424A: Upper limits from a search for additional neutrino events in IceCube
  10. IceCube-220421A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 220427A: Swift-BAT refined analysis
  12. GRB 220427A: VLT/X-shooter photometry
  13. GRB 220426A: Swift-XRT and UVOT observations
  14. GRB 220423A: Detection by VZLUSAT-2
  15. Konus-Wind detection of GRB 220427A
  16. GRB 220427A: Swift-XRT refined Analysis
  17. GRB 220427A: Enhanced Swift-XRT position
  18. GRB 220426A: Tiled Swift observations
  19. GRB 220427A: Swift detection of a burst with an optical counterpart
  20. Konus-Wind detection of GRB 220426A
  21. IPN triangulation of GRB 220426A
  22. GRB 220426C: Swift/BAT-GUANO detection outside the coded FOV (short)
  23. Fermi GRB 220426A: Global MASTER-Net observations report
  24. GRB 220426A: Fermi GBM detection
  25. GRB 220426A: Swift/BAT-GUANO detection outside the coded FOV
  26. Fermi-LAT Gamma-ray Observations of IceCube-220425A
  27. Fermi GRB 220426B: Global MASTER-Net observations report
  28. GRB 220426B: Fermi GBM Final Real-time Localization
  29. GRB 220426A: BALROG localization (Fermi Trigger 672648596/ GRB 220426285)
  30. Correction to 31937: GRB 220421B: Detection by VZLUSAT-2
  31. IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate
  32. Fermi-LAT Gamma-ray Observations of IceCube-220424A
  33. IceCube Alert 220425.11: Global MASTER-Net observations report
  34. Fermi trigger No 672492774: Global MASTER-Net observations report
  35. IceCube-220425A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 220423A: Swift/BAT-GUANO detection outside the coded FOV
  37. IceCube-220424A - IceCube observation of a high-energy neutrino candidate track-like event
  38. IceCube Alert 220424.05: Global MASTER-Net observations report
  39. Fermi trigger No 672374264: Global MASTER-Net observations report
  40. On the AGILE detection of GRB 220423A
  41. GRB 220423A: AGILE detection
  42. GRB 220421B: Detection by VZLUSAT-2
  43. GRB 220421A: Fermi GBM observation
  44. Fermi-LAT Gamma-ray Observations of IceCube-220421A
  45. GRB 220421A: Swift/BAT-GUANO detection outside the coded FOV
  46. Fermi trigger No 672221879: Global MASTER-Net observations report
  47. Fermi GBM trigger 672128054/220420260 is not a GRB
  48. IceCube-220421A - IceCube observation of a high-energy neutrino candidate track-like event
  49. GRB 220418B: Swift-XRT observations
  50. IceCube Alert 220421.22: Global MASTER-Net observations report
  51. GRB 220418B Fermi GBM observation
  52. Fermi trigger No 672093919: Global MASTER-Net observations report
  53. “GRB 220420A” is not a GRB
  54. GRB 220420A: Swift/BAT-GUANO detection outside the coded FOV
  55. GRB 220403C: Further Swift-XRT observations
  56. GRB 220418B: Swift ToO observations
  57. GRB 220417A: Fermi GBM detection
  58. GRB 220418B: Swift/BAT-GUANO refined location of a short burst
  59. IPN triangulation of GRB 220411A
  60. GRB 220418B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  61. GRB 220417A: Swift/BAT-GUANO detection outside the coded FOV
  62. GRB 220412B: Swift/UVOT Upper Limits
  63. Fermi GRB 220418A: Global MASTER-Net observations report
  64. GRB 220418B: Fermi GBM Final Real-time Localization
  65. GRB 220418A: Fermi GBM Final Real-time Localization
  66. Fermi GRB 220417A: Global MASTER-Net observations report
  67. GRB 220417A: Fermi GBM Final Real-time Localization
  68. Fermi trigger No 671729344: Global MASTER-Net observations report
  69. GRB 220412B: Swift-BAT refined analysis
  70. Konus-Wind detection of GRB 220412B
  71. GRB 220412B: Fermi GBM observation
  72. Konus-Wind detection of GRB 220403C
  73. GRB 220408B: Fermi GBM observation
  74. Konus-Wind detection of GRB 220408B
  75. GRB 220412B: TNG optical observations
  76. GRB 220412A: GRANDMA observations
  77. GRB 220412A: Continued RATIR Observations and Steepening of the Light Curve
  78. GRB 220412A: BOOTES-network optical upper limits
  79. GRB 220412B: BOOTES-1 optical upper limit
  80. GRB 220412A: Swift-BAT refined analysis
  81. GRB 220412A: RATIR Observations of the Fading Afterglow
  82. GRB 220412B: Swift-XRT observations
  83. GRB 220408B: Fermi-LAT detection
  84. IPN triangulation of short/soft GRB 220406A
  85. Swift GRB 220412B: Global MASTER-Net observations report
  86. GRB 220408A: HCT optical upper limit
  87. GRB 220412B: GIT optical upper limit
  88. GRB 220412A: MITSuME Akeno optical upper limits
  89. Correction to GCN 31888: GRB 220412A: Swift-XRT refined Analysis
  90. GRB 220412B: MITSuME Akeno optical upper limits
  91. GRB 220412A: Swift-XRT refined Analysis
  92. GRB 220412A: Enhanced Swift-XRT position
  93. GRB 220412B: Swift detection of a short burst
  94. GRB 220412A: Swift/UVOT Upper Limits
  95. GRB 220408A: GRANDMA observations
  96. GRB 220403B: GRANDMA observations
  97. GRB 220412A: RATIR Afterglow Candidate
  98. GRB 220412A: Swift detection of a burst
  99. Swift GRB220412.28: Global MASTER-Net observations report
  100. GRB 220411A: AstroSat CZTI detection

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