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

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