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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. IPN triangulation of GRB 210606B
  2. IceCube-210608A: IceCube observation of a high-energy neutrino candidate track-like event
  3. IceCube Alert 210608.15: Global MASTER-Net observations report
  4. Fermi Gamma-ray Burst Monitor trigger 644793834 / 210607892 is not a GRB
  5. GRB 210607A/MAXI J1733-222: MAXI/GSC detection
  6. MAXI GRB210607.82: Global MASTER-Net observations report
  7. Fermi trigger No 644793834: Global MASTER-Net observations report
  8. GRB 210606B: Fermi GBM detection
  9. GRB 210605B: Swift-XRT observations
  10. Konus-Wind detection of GRB 210602A
  11. Konus-Wind detection of GRB 210605A (short/hard)
  12. IPN triangulation of GRB 210605A (short)
  13. GRB 210606B: AGILE detection
  14. GRB 210606A: 1.5m OSN optical upper limit
  15. GECAM Sub-Threshold Detection of new magnetar Swift SGR J1555.2-5402
  16. GRB 210606B: BALROG localization (Fermi Trigger 644712030 / GRB 210606945)
  17. GRB 210606B: GECAM detection
  18. Fermi trigger No 644712030: Global MASTER-Net observations report
  19. GRB 210606A: Swift ToO observations
  20. Fermi GRB 210606A: DDOTI Upper Limits on the Afterglow
  21. GRB 210606A: Swift/BAT-GUANO detection and arcminute localization
  22. GRB 210605B: Swift ToO observations
  23. Fermi GRB 210606A: Global MASTER-Net observations report
  24. GRB 210606A: Fermi GBM Final Real-time Localization
  25. GRB 210605B: Swift/BAT-GUANO detection and arcminute localization
  26. GRB 210605B: Fermi GBM Final Real-time Localization
  27. Fermi GRB 210605A: Global MASTER-Net observations report
  28. GRB 210605A: Fermi GBM Final Real-time Localization
  29. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  30. Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402
  31. SGR J1555.2-5402: Swift-BAT refined analysis
  32. Fermi trigger No 644449593: Global MASTER-Net observations report
  33. Swift J1555.2-5402: Swift XRT refined analysis of the new SGR
  34. NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
  35. Swift Detection of probable new Swift SGR J1555.2-5402
  36. MAXI GRB210602.50: Global MASTER-Net observations report
  37. Swift GRB210603.41: Global MASTER-Net observations report
  38. GRB 210602A: CALET Gamma-Ray Burst Monitor detection
  39. GRB 210602B: GECAM detection
  40. GRB 210529A: GECAM detection
  41. Fermi trigger No 644359567: Global MASTER-Net observations report
  42. GRB 210602A: MAXI/GSC detection
  43. Fermi GRB 210601A: Global MASTER-Net observations report
  44. GRB 210601A: Fermi GBM Final Real-time Localization
  45. IPN triangulation of GRB 210531A
  46. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  47. GRB 210531A: AstroSat CZTI detection
  48. Fermi trigger No 644155206: Global MASTER-Net observations report
  49. GRB 210531A: AGILE/MCAL detection (Fermi Trigger 644155206 / GRB 210531500)
  50. GRB 210531A: BALROG localization (Fermi Trigger 644155206 / GRB 210531500)
  51. GRB 210529B: DDOTI Upper Limits on the Afterglow
  52. Fermi GRB 210529A: Global MASTER-Net observations report
  53. Fermi GRB 210529B: Global MASTER-Net observations report
  54. GRB 210529B: Fermi GBM Final Real-time Localization
  55. GRB 210529A: Fermi GBM Final Real-time Localization
  56. GRB 210528A: Fermi GBM detection
  57. GRB 210528A: AstroSat CZTI detection
  58. GRB 210528B: DDOTI Upper Limits on the Afterglow
  59. GRB 210528B: MITSuME Akeno optical upper limits
  60. MAXI GRB210528.95: Global MASTER-Net observations report
  61. GRB 210528B: MAXI/GSC detection
  62. Fermi GRB 210528A: Global MASTER-Net observations report
  63. GRB 210527A: Swift-BAT refined analysis
  64. GRB 210528A: BALROG localization (Fermi Trigger 643903431 / GRB 210528586)
  65. GRB 210528A: Fermi GBM Final Real-time Localization
  66. GRB 210527A: Swift/UVOT Observations
  67. GRB 210527A: GIT optical upper limit
  68. GRB 210527A: MITSuME Akeno optical upper limits
  69. Swift GRB 210527A: Global MASTER-Net observations report
  70. GRB 210527A: Swift-XRT refined Analysis
  71. GRB 210527A: RATIR Optical and NIR Observations
  72. GRB 210527A: Enhanced Swift-XRT position
  73. GRB 210527A: Swift-XRT observations
  74. GRB 210527A: Swift detection of a burst
  75. GRB 210306A: LBT observations of the likely host galaxy
  76. ZTF21aayokph (AT2021lfa): LBT optical observations
  77. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  78. Konus-Wind detection of GRB 210524A
  79. IPN triangulation of GRB 210524A
  80. Fermi trigger No 643548039: Global MASTER-Net observations report
  81. GRB 210524B: Fermi GBM Final Real-time Localization
  82. GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
  83. Fermi GRB 210524A: Global MASTER-Net observations report
  84. GRB 210524A: Fermi GBM Final Real-time Localization
  85. GRB 210522A: GECAM detection
  86. GRB 210520A: Swift-XRT observations
  87. MAXI GRB210521.54: Global MASTER-Net observations report
  88. GRB 210521A: MAXI/GSC detection
  89. GRB210413B: further Swift-XRT observations
  90. GRB 210520A: Fermi GBM detection
  91. ZTF21aayokph (AT2021lfa): continued Assy optical observations
  92. GRB 210520A: Tiled Swift observations
  93. GRB 210520A: Fermi-LAT detection
  94. GRB 210520A: GECAM detection
  95. Fermi GRB 210520A: Global MASTER-Net observations report
  96. GRB 210520A: Fermi GBM Final Real-time Localization
  97. Fermi GBM observation of a bright burst from magneta
  98. GRB 210517A: KCT optical upper limit
  99. IceCube GCN alert 135302_36915486.amon retraction
  100. Fermi GRB 210519A: Global MASTER-Net observations report

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