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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 220426A: Tiled Swift observations
  2. GRB 220427A: Swift detection of a burst with an optical counterpart
  3. Konus-Wind detection of GRB 220426A
  4. IPN triangulation of GRB 220426A
  5. GRB 220426C: Swift/BAT-GUANO detection outside the coded FOV (short)
  6. Fermi GRB 220426A: Global MASTER-Net observations report
  7. GRB 220426A: Fermi GBM detection
  8. GRB 220426A: Swift/BAT-GUANO detection outside the coded FOV
  9. Fermi-LAT Gamma-ray Observations of IceCube-220425A
  10. Fermi GRB 220426B: Global MASTER-Net observations report
  11. GRB 220426B: Fermi GBM Final Real-time Localization
  12. GRB 220426A: BALROG localization (Fermi Trigger 672648596/ GRB 220426285)
  13. Correction to 31937: GRB 220421B: Detection by VZLUSAT-2
  14. IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate
  15. Fermi-LAT Gamma-ray Observations of IceCube-220424A
  16. IceCube Alert 220425.11: Global MASTER-Net observations report
  17. Fermi trigger No 672492774: Global MASTER-Net observations report
  18. IceCube-220425A - IceCube observation of a high-energy neutrino candidate track-like event
  19. GRB 220423A: Swift/BAT-GUANO detection outside the coded FOV
  20. IceCube-220424A - IceCube observation of a high-energy neutrino candidate track-like event
  21. IceCube Alert 220424.05: Global MASTER-Net observations report
  22. Fermi trigger No 672374264: Global MASTER-Net observations report
  23. On the AGILE detection of GRB 220423A
  24. GRB 220423A: AGILE detection
  25. GRB 220421B: Detection by VZLUSAT-2
  26. GRB 220421A: Fermi GBM observation
  27. Fermi-LAT Gamma-ray Observations of IceCube-220421A
  28. GRB 220421A: Swift/BAT-GUANO detection outside the coded FOV
  29. Fermi trigger No 672221879: Global MASTER-Net observations report
  30. Fermi GBM trigger 672128054/220420260 is not a GRB
  31. IceCube-220421A - IceCube observation of a high-energy neutrino candidate track-like event
  32. GRB 220418B: Swift-XRT observations
  33. IceCube Alert 220421.22: Global MASTER-Net observations report
  34. GRB 220418B Fermi GBM observation
  35. Fermi trigger No 672093919: Global MASTER-Net observations report
  36. “GRB 220420A” is not a GRB
  37. GRB 220420A: Swift/BAT-GUANO detection outside the coded FOV
  38. GRB 220403C: Further Swift-XRT observations
  39. GRB 220418B: Swift ToO observations
  40. GRB 220417A: Fermi GBM detection
  41. GRB 220418B: Swift/BAT-GUANO refined location of a short burst
  42. IPN triangulation of GRB 220411A
  43. GRB 220418B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  44. GRB 220417A: Swift/BAT-GUANO detection outside the coded FOV
  45. GRB 220412B: Swift/UVOT Upper Limits
  46. Fermi GRB 220418A: Global MASTER-Net observations report
  47. GRB 220418B: Fermi GBM Final Real-time Localization
  48. GRB 220418A: Fermi GBM Final Real-time Localization
  49. Fermi GRB 220417A: Global MASTER-Net observations report
  50. GRB 220417A: Fermi GBM Final Real-time Localization
  51. Fermi trigger No 671729344: Global MASTER-Net observations report
  52. GRB 220412B: Swift-BAT refined analysis
  53. Konus-Wind detection of GRB 220412B
  54. GRB 220412B: Fermi GBM observation
  55. Konus-Wind detection of GRB 220403C
  56. GRB 220408B: Fermi GBM observation
  57. Konus-Wind detection of GRB 220408B
  58. GRB 220412B: TNG optical observations
  59. GRB 220412A: GRANDMA observations
  60. GRB 220412A: Continued RATIR Observations and Steepening of the Light Curve
  61. GRB 220412A: BOOTES-network optical upper limits
  62. GRB 220412B: BOOTES-1 optical upper limit
  63. GRB 220412A: Swift-BAT refined analysis
  64. GRB 220412A: RATIR Observations of the Fading Afterglow
  65. GRB 220412B: Swift-XRT observations
  66. GRB 220408B: Fermi-LAT detection
  67. IPN triangulation of short/soft GRB 220406A
  68. Swift GRB 220412B: Global MASTER-Net observations report
  69. GRB 220408A: HCT optical upper limit
  70. GRB 220412B: GIT optical upper limit
  71. GRB 220412A: MITSuME Akeno optical upper limits
  72. Correction to GCN 31888: GRB 220412A: Swift-XRT refined Analysis
  73. GRB 220412B: MITSuME Akeno optical upper limits
  74. GRB 220412A: Swift-XRT refined Analysis
  75. GRB 220412A: Enhanced Swift-XRT position
  76. GRB 220412B: Swift detection of a short burst
  77. GRB 220412A: Swift/UVOT Upper Limits
  78. GRB 220408A: GRANDMA observations
  79. GRB 220403B: GRANDMA observations
  80. GRB 220412A: RATIR Afterglow Candidate
  81. GRB 220412A: Swift detection of a burst
  82. Swift GRB220412.28: Global MASTER-Net observations report
  83. GRB 220411A: AstroSat CZTI detection
  84. IPN triangulation of GRB 220408B
  85. IPN triangulation of GRB 220403C
  86. GRB 220403B: Swift/UVOT Detection
  87. GRB 220408A: Lowell Discovery Telescope Optical Observations
  88. GRB 220408A: Swift-BAT refined analysis
  89. Fermi GRB 220411A: Global MASTER-Net observations report
  90. GRB 220411A: BALROG localization (Fermi Trigger 671354405/ GRB 220411306)
  91. GRB 220411A: Fermi GBM Final Real-time Localization
  92. GRB 220408A: RATIR Optical and NIR Observations
  93. GRB 220403B: 1.3m DFOT Optical upper limit
  94. GRB 220408A: 1.3m DFOT Optical upper limit
  95. GRB 220408A: LOAO, DOAO, and, SAO optical upper limit
  96. GRB 220403C: Swift-XRT observations
  97. GRB 220408A: redshift lower limit estimating
  98. GRB 220408A: NOT optical observations and archival detection
  99. GRB 220408B: AstroSat CZTI detection
  100. GRB 220408A: LCO Optical Afterglow Detection

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