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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. Fermi trigger No 644793834: Global MASTER-Net observations report
  2. GRB 210606B: Fermi GBM detection
  3. GRB 210605B: Swift-XRT observations
  4. Konus-Wind detection of GRB 210602A
  5. Konus-Wind detection of GRB 210605A (short/hard)
  6. IPN triangulation of GRB 210605A (short)
  7. GRB 210606B: AGILE detection
  8. GRB 210606A: 1.5m OSN optical upper limit
  9. GECAM Sub-Threshold Detection of new magnetar Swift SGR J1555.2-5402
  10. GRB 210606B: BALROG localization (Fermi Trigger 644712030 / GRB 210606945)
  11. GRB 210606B: GECAM detection
  12. Fermi trigger No 644712030: Global MASTER-Net observations report
  13. GRB 210606A: Swift ToO observations
  14. Fermi GRB 210606A: DDOTI Upper Limits on the Afterglow
  15. GRB 210606A: Swift/BAT-GUANO detection and arcminute localization
  16. GRB 210605B: Swift ToO observations
  17. Fermi GRB 210606A: Global MASTER-Net observations report
  18. GRB 210606A: Fermi GBM Final Real-time Localization
  19. GRB 210605B: Swift/BAT-GUANO detection and arcminute localization
  20. GRB 210605B: Fermi GBM Final Real-time Localization
  21. Fermi GRB 210605A: Global MASTER-Net observations report
  22. GRB 210605A: Fermi GBM Final Real-time Localization
  23. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  24. Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402
  25. SGR J1555.2-5402: Swift-BAT refined analysis
  26. Fermi trigger No 644449593: Global MASTER-Net observations report
  27. Swift J1555.2-5402: Swift XRT refined analysis of the new SGR
  28. NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
  29. Swift Detection of probable new Swift SGR J1555.2-5402
  30. MAXI GRB210602.50: Global MASTER-Net observations report
  31. Swift GRB210603.41: Global MASTER-Net observations report
  32. GRB 210602A: CALET Gamma-Ray Burst Monitor detection
  33. GRB 210602B: GECAM detection
  34. GRB 210529A: GECAM detection
  35. Fermi trigger No 644359567: Global MASTER-Net observations report
  36. GRB 210602A: MAXI/GSC detection
  37. Fermi GRB 210601A: Global MASTER-Net observations report
  38. GRB 210601A: Fermi GBM Final Real-time Localization
  39. IPN triangulation of GRB 210531A
  40. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  41. GRB 210531A: AstroSat CZTI detection
  42. Fermi trigger No 644155206: Global MASTER-Net observations report
  43. GRB 210531A: AGILE/MCAL detection (Fermi Trigger 644155206 / GRB 210531500)
  44. GRB 210531A: BALROG localization (Fermi Trigger 644155206 / GRB 210531500)
  45. GRB 210529B: DDOTI Upper Limits on the Afterglow
  46. Fermi GRB 210529A: Global MASTER-Net observations report
  47. Fermi GRB 210529B: Global MASTER-Net observations report
  48. GRB 210529B: Fermi GBM Final Real-time Localization
  49. GRB 210529A: Fermi GBM Final Real-time Localization
  50. GRB 210528A: Fermi GBM detection
  51. GRB 210528A: AstroSat CZTI detection
  52. GRB 210528B: DDOTI Upper Limits on the Afterglow
  53. GRB 210528B: MITSuME Akeno optical upper limits
  54. MAXI GRB210528.95: Global MASTER-Net observations report
  55. GRB 210528B: MAXI/GSC detection
  56. Fermi GRB 210528A: Global MASTER-Net observations report
  57. GRB 210527A: Swift-BAT refined analysis
  58. GRB 210528A: BALROG localization (Fermi Trigger 643903431 / GRB 210528586)
  59. GRB 210528A: Fermi GBM Final Real-time Localization
  60. GRB 210527A: Swift/UVOT Observations
  61. GRB 210527A: GIT optical upper limit
  62. GRB 210527A: MITSuME Akeno optical upper limits
  63. Swift GRB 210527A: Global MASTER-Net observations report
  64. GRB 210527A: Swift-XRT refined Analysis
  65. GRB 210527A: RATIR Optical and NIR Observations
  66. GRB 210527A: Enhanced Swift-XRT position
  67. GRB 210527A: Swift-XRT observations
  68. GRB 210527A: Swift detection of a burst
  69. GRB 210306A: LBT observations of the likely host galaxy
  70. ZTF21aayokph (AT2021lfa): LBT optical observations
  71. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  72. Konus-Wind detection of GRB 210524A
  73. IPN triangulation of GRB 210524A
  74. Fermi trigger No 643548039: Global MASTER-Net observations report
  75. GRB 210524B: Fermi GBM Final Real-time Localization
  76. GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
  77. Fermi GRB 210524A: Global MASTER-Net observations report
  78. GRB 210524A: Fermi GBM Final Real-time Localization
  79. GRB 210522A: GECAM detection
  80. GRB 210520A: Swift-XRT observations
  81. MAXI GRB210521.54: Global MASTER-Net observations report
  82. GRB 210521A: MAXI/GSC detection
  83. GRB210413B: further Swift-XRT observations
  84. GRB 210520A: Fermi GBM detection
  85. ZTF21aayokph (AT2021lfa): continued Assy optical observations
  86. GRB 210520A: Tiled Swift observations
  87. GRB 210520A: Fermi-LAT detection
  88. GRB 210520A: GECAM detection
  89. Fermi GRB 210520A: Global MASTER-Net observations report
  90. GRB 210520A: Fermi GBM Final Real-time Localization
  91. Fermi GBM observation of a bright burst from magneta
  92. GRB 210517A: KCT optical upper limit
  93. IceCube GCN alert 135302_36915486.amon retraction
  94. Fermi GRB 210519A: Global MASTER-Net observations report
  95. IceCube Alert 210519.86: Global MASTER-Net observations report
  96. IPN triangulation of GRB 210518A
  97. Fermi trigger No 643065622: Global MASTER-Net observations report
  98. GRB 210518.889: DDOTI Upper Limits on the Afterglow
  99. GRB 210519A: Fermi GBM Final Localization
  100. Fermi GRB 210518A: Global MASTER-Net observations report

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