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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').
  1. GRB 210901A: Swift/UVOT Upper Limits
  2. Swift GRB 210905A: Global MASTER-Net observations report
  3. GRB 210905A: Swift detection of a burst
  4. Fermi GRB 210904A: Global MASTER-Net observations report
  5. GRB 210904A: Fermi GBM Final Real-time Localization
  6. Swift GRB210903.59: Global MASTER-Net observations report
  7. Swift GRB210903.58: Global MASTER-Net observations report
  8. Swift GRB210903.58: Global MASTER-Net observations report
  9. Fermi GRB 210903A: Global MASTER-Net observations report
  10. GRB 210903C: Fermi GBM Final Real-time Localization
  11. GRB 210820A: TSHAO optical upper limit
  12. Fermi GRB 210903B: Global MASTER-Net observations report
  13. GRB 210901A: GROND observations
  14. GRB 210903B: Fermi GBM Final Localization
  15. Fermi GBM observation of a burst from SGR J1555.2-5402
  16. GRB 210903A: Fermi GBM Final Real-time Localization
  17. GRB 210901A: Swift-XRT refined Analysis
  18. GRB 210901A: Swift-BAT refined analysis
  19. GRB 210901A: Enhanced Swift-XRT position
  20. GRB 210901A: LCO Optical Upper Limit
  21. Swift GRB 210901A: Global MASTER-Net observations report
  22. GRB 210901A: Swift detection of a burst
  23. GRB 210827A: further Swift-XRT observations
  24. GRB 210822A: CALET Gamma-Ray Burst Monitor detection
  25. GRB 210827A: Swift/UVOT Upper Limits
  26. GRB 210827A: BOOTES-5/JGT optical upper limit
  27. Integral GRB210829.17: Global MASTER-Net observations report
  28. IBAS Alert n. 9366 not a GRB
  29. Integral GRB210829.14: Global MASTER-Net observations report
  30. GRB 210827A: Fermi GBM Observation
  31. GRB 210826A: AstroSat CZTI detection
  32. Fermi GRB 210827A: Global MASTER-Net observations report
  33. Fermi GRB 210827B: Global MASTER-Net observations report
  34. GRB 210827A: Swift-XRT observations
  35. GRB 210827A: Swift ToO observations
  36. GRB 210827A: Swift/BAT-GUANO detection and arcminute localization
  37. GRB 210820A: CAHA 2.2m Optical Detection
  38. GRB 210824A: Swift/UVOT Upper Limits
  39. GRB 210826A: Swift/UVOT Upper Limits
  40. POLAR detection of a SGR-like burst
  41. GRB 210827B: BALROG localization (Fermi Trigger 651751821 / GRB 210827424)
  42. GRB 210827B: Fermi GBM Final Real-time Localization
  43. GRB 210826A: Swift-XRT observations
  44. GRB 210827A: Fermi GBM Final Real-time Localization
  45. GRB 210822A: CAHA 2.2m observations
  46. GRB 210824A: Swift-BAT refined analysis
  47. GRB 210826A: Fermi-LAT detection
  48. Fermi GRB 210826A: Global MASTER-Net observations report
  49. GRB 210826A: Tiled Swift observations
  50. GRB 210824A: MITSuME Akeno optical upper limits
  51. GRB 210826A: BALROG localization (Fermi Trigger 651654110 / GRB 210826293)
  52. GRB 210826A: Fermi GBM Final Real-time Localization
  53. Swift GRB210825.29: Global MASTER-Net observations report
  54. GRB 210822A: TSHAO continued optical observation
  55. GRB 210822A: VLA detection
  56. GRB 210822A: TSHAO optical observation
  57. Swift detection of an outburst from SGR Swift J1555.2-5402
  58. GRB 210822A: Swift/UVOT Detection
  59. Swift GRB 210824A: Global MASTER-Net observations report
  60. GRB 210824A: BOOTES-5/JGT optical upper limit
  61. GRB 210824A: Fermi GBM Observation
  62. Fermi GRB 210824A: Global MASTER-Net observations report
  63. GRB 210824A: Nanshan/NEXT optical upper limit
  64. GRB 210824A: Swift-XRT refined Analysis
  65. GRB 210822A: GROND observations
  66. GRB 210824A: Enhanced Swift-XRT position
  67. GRB 210822A: Abbey Ridge Observatory optical afterglow observation
  68. GRB 210824A: Swift detection of a burst
  69. GRB 210824A: Fermi GBM Final Real-time Localization
  70. GRB 210822B: DDOTI Upper Limits on the Afterglow
  71. GRB 210822A: Detection by GRBAlpha
  72. GRB 210822A: GECAM refined analysis
  73. GRB 210820A: GROND observations
  74. Konus-Wind detection of GRB 210822A
  75. GRB 210822A: AstroSat CZTI detection
  76. GRB 210822A: NOT photometry and spectroscopy
  77. GRB 210822A: Swift-XRT refined Analysis
  78. Fermi trigger No 651306769: Global MASTER-Net observations report
  79. GRB 210822A: Swift-BAT refined analysis
  80. GRB 210820A: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  81. GRB 210822A: Fermi-LAT detection
  82. GRB 210820A: Swift/UVOT Detection
  83. Fermi GRB 210822B: Global MASTER-Net observations report
  84. GRB 210822A: Nanshan/NEXT optical observations
  85. GRB 210822B: Fermi GBM Final Real-time Localization
  86. GRB 210822A: Enhanced Swift-XRT position
  87. Swift GRB 210822A: Global MASTER-Net observations report
  88. GRB 210822A: RATIR Optical Detections
  89. GRB 210822A: KAIT Optical Afterglow Confirmation
  90. GRB 210822A: GECAM detection
  91. GRB 210822A: Swift detection of a burst with an optical afterglow
  92. Fermi GRB 210821A: Global MASTER-Net observations report
  93. GRB 210820A: Swift-BAT refined analysis
  94. GRB 210820A: LT optical upper limit
  95. GRB 210820A: LCO Optical Upper Limit
  96. GRB 210820A: RATIR Optical Detections
  97. GRB 210821A: Fermi GBM Final Real-time Localization
  98. GRB 210820A: NOT optical upper limit
  99. GRB 210820A: Nanshan/NEXT optical upper limit
  100. GRB 210820A: Swift-XRT refined Analysis

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