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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 220501A: Fermi GBM observation
  2. GRB 220430A: AstroSat CZTI detection
  3. IceCube-220501A - IceCube observation of a high-energy neutrino candidate track-like event
  4. IceCube Alert 220501.95: Global MASTER-Net observations report
  5. GRB 220501A: GRANDMA/TJML Optical Observations
  6. GRB 220501A: Fermi GBM Final Real-time Localization
  7. GRB 220501A: Swift detection of a burst
  8. GRB 220430A: Swift-BAT refined analysis
  9. GRB 220430A: CAHA 2.2m telescope optical limit
  10. GRB 220430A: Swift-XRT refined Analysis
  11. Swift GRB 220430A: Global MASTER-Net observations report
  12. GRB 220430A: GRANDMA observations
  13. GRB 220430A: Mondy and AbAO optical upper limits
  14. GRB 220430A: AGILE detection
  15. GRB 220430A: MeerLICHT optical upper limits
  16. GRB 220430A: Enhanced Swift-XRT position
  17. GRB 220430A: Swift detection of a burst or Swift J0630.4+0932
  18. IceCube-220425A: Upper limits from a search for additional neutrino events in IceCube
  19. IceCube-220424A: Upper limits from a search for additional neutrino events in IceCube
  20. IceCube-220421A: Upper limits from a search for additional neutrino events in IceCube
  21. GRB 220427A: Swift-BAT refined analysis
  22. GRB 220427A: VLT/X-shooter photometry
  23. GRB 220426A: Swift-XRT and UVOT observations
  24. GRB 220423A: Detection by VZLUSAT-2
  25. Konus-Wind detection of GRB 220427A
  26. GRB 220427A: Swift-XRT refined Analysis
  27. GRB 220427A: Enhanced Swift-XRT position
  28. GRB 220426A: Tiled Swift observations
  29. GRB 220427A: Swift detection of a burst with an optical counterpart
  30. Konus-Wind detection of GRB 220426A
  31. IPN triangulation of GRB 220426A
  32. GRB 220426C: Swift/BAT-GUANO detection outside the coded FOV (short)
  33. Fermi GRB 220426A: Global MASTER-Net observations report
  34. GRB 220426A: Fermi GBM detection
  35. GRB 220426A: Swift/BAT-GUANO detection outside the coded FOV
  36. Fermi-LAT Gamma-ray Observations of IceCube-220425A
  37. Fermi GRB 220426B: Global MASTER-Net observations report
  38. GRB 220426B: Fermi GBM Final Real-time Localization
  39. GRB 220426A: BALROG localization (Fermi Trigger 672648596/ GRB 220426285)
  40. Correction to 31937: GRB 220421B: Detection by VZLUSAT-2
  41. IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate
  42. Fermi-LAT Gamma-ray Observations of IceCube-220424A
  43. IceCube Alert 220425.11: Global MASTER-Net observations report
  44. Fermi trigger No 672492774: Global MASTER-Net observations report
  45. IceCube-220425A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 220423A: Swift/BAT-GUANO detection outside the coded FOV
  47. IceCube-220424A - IceCube observation of a high-energy neutrino candidate track-like event
  48. IceCube Alert 220424.05: Global MASTER-Net observations report
  49. Fermi trigger No 672374264: Global MASTER-Net observations report
  50. On the AGILE detection of GRB 220423A
  51. GRB 220423A: AGILE detection
  52. GRB 220421B: Detection by VZLUSAT-2
  53. GRB 220421A: Fermi GBM observation
  54. Fermi-LAT Gamma-ray Observations of IceCube-220421A
  55. GRB 220421A: Swift/BAT-GUANO detection outside the coded FOV
  56. Fermi trigger No 672221879: Global MASTER-Net observations report
  57. Fermi GBM trigger 672128054/220420260 is not a GRB
  58. IceCube-220421A - IceCube observation of a high-energy neutrino candidate track-like event
  59. GRB 220418B: Swift-XRT observations
  60. IceCube Alert 220421.22: Global MASTER-Net observations report
  61. GRB 220418B Fermi GBM observation
  62. Fermi trigger No 672093919: Global MASTER-Net observations report
  63. “GRB 220420A” is not a GRB
  64. GRB 220420A: Swift/BAT-GUANO detection outside the coded FOV
  65. GRB 220403C: Further Swift-XRT observations
  66. GRB 220418B: Swift ToO observations
  67. GRB 220417A: Fermi GBM detection
  68. GRB 220418B: Swift/BAT-GUANO refined location of a short burst
  69. IPN triangulation of GRB 220411A
  70. GRB 220418B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  71. GRB 220417A: Swift/BAT-GUANO detection outside the coded FOV
  72. GRB 220412B: Swift/UVOT Upper Limits
  73. Fermi GRB 220418A: Global MASTER-Net observations report
  74. GRB 220418B: Fermi GBM Final Real-time Localization
  75. GRB 220418A: Fermi GBM Final Real-time Localization
  76. Fermi GRB 220417A: Global MASTER-Net observations report
  77. GRB 220417A: Fermi GBM Final Real-time Localization
  78. Fermi trigger No 671729344: Global MASTER-Net observations report
  79. GRB 220412B: Swift-BAT refined analysis
  80. Konus-Wind detection of GRB 220412B
  81. GRB 220412B: Fermi GBM observation
  82. Konus-Wind detection of GRB 220403C
  83. GRB 220408B: Fermi GBM observation
  84. Konus-Wind detection of GRB 220408B
  85. GRB 220412B: TNG optical observations
  86. GRB 220412A: GRANDMA observations
  87. GRB 220412A: Continued RATIR Observations and Steepening of the Light Curve
  88. GRB 220412A: BOOTES-network optical upper limits
  89. GRB 220412B: BOOTES-1 optical upper limit
  90. GRB 220412A: Swift-BAT refined analysis
  91. GRB 220412A: RATIR Observations of the Fading Afterglow
  92. GRB 220412B: Swift-XRT observations
  93. GRB 220408B: Fermi-LAT detection
  94. IPN triangulation of short/soft GRB 220406A
  95. Swift GRB 220412B: Global MASTER-Net observations report
  96. GRB 220408A: HCT optical upper limit
  97. GRB 220412B: GIT optical upper limit
  98. GRB 220412A: MITSuME Akeno optical upper limits
  99. Correction to GCN 31888: GRB 220412A: Swift-XRT refined Analysis
  100. GRB 220412B: MITSuME Akeno optical upper limits

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