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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. GECAM observation of a burst from SGR J1935+2154
  2. Fermi trigger No 652927551: Global MASTER-Net observations report
  3. GRB 210619B: Maidanak and Assy optical observations, broken power law parametrization
  4. Fermi trigger No 652911693: Global MASTER-Net observations report
  5. Fermi trigger No 652906639: Global MASTER-Net observations report
  6. Fermi GRB 210909A: Global MASTER-Net observations report
  7. GECAM observation of a burst from SGR J1555.2-5402
  8. GRB 210909A: Fermi GBM Final Real-time Localization
  9. GRB 210905A: Swift/UVOT Upper Limits
  10. GRB 210905A: ATCA detection
  11. GRB 210905A: ALMA detection
  12. GRB 210905A: AstroSat CZTI detection
  13. GRB 210905A, GROND observations
  14. Konus-Wind detection of GRB 210905A
  15. Fermi GBM Sub-Threshold Detection of GRB 210905A
  16. Fermi GBM trigger 652585475 / 210906073 is not a GRB
  17. Fermi trigger No 652585475: Global MASTER-Net observations report
  18. GRB 210905A: Swift-XRT refined Analysis
  19. GRB 210610A: Maidanak and AbAO optical observations
  20. GRB 210827B: GECAM detection
  21. GRB 210905A: DECam Detection
  22. GRB 210905A: REM NIR afterglow detection
  23. GRB 210905A: VLT/X-shooter spectroscopic redshift
  24. GRB 210905A: Continued LCO Optical Observations
  25. GRB 210905A: LCO Optical Detection
  26. GRB 210905A: Enhanced Swift-XRT position
  27. GRB 210901A: Swift/UVOT Upper Limits
  28. Swift GRB 210905A: Global MASTER-Net observations report
  29. GRB 210905A: Swift detection of a burst
  30. Fermi GRB 210904A: Global MASTER-Net observations report
  31. GRB 210904A: Fermi GBM Final Real-time Localization
  32. Swift GRB210903.59: Global MASTER-Net observations report
  33. Swift GRB210903.58: Global MASTER-Net observations report
  34. Swift GRB210903.58: Global MASTER-Net observations report
  35. Fermi GRB 210903A: Global MASTER-Net observations report
  36. GRB 210903C: Fermi GBM Final Real-time Localization
  37. GRB 210820A: TSHAO optical upper limit
  38. Fermi GRB 210903B: Global MASTER-Net observations report
  39. GRB 210901A: GROND observations
  40. GRB 210903B: Fermi GBM Final Localization
  41. Fermi GBM observation of a burst from SGR J1555.2-5402
  42. GRB 210903A: Fermi GBM Final Real-time Localization
  43. GRB 210901A: Swift-XRT refined Analysis
  44. GRB 210901A: Swift-BAT refined analysis
  45. GRB 210901A: Enhanced Swift-XRT position
  46. GRB 210901A: LCO Optical Upper Limit
  47. Swift GRB 210901A: Global MASTER-Net observations report
  48. GRB 210901A: Swift detection of a burst
  49. GRB 210827A: further Swift-XRT observations
  50. GRB 210822A: CALET Gamma-Ray Burst Monitor detection
  51. GRB 210827A: Swift/UVOT Upper Limits
  52. GRB 210827A: BOOTES-5/JGT optical upper limit
  53. Integral GRB210829.17: Global MASTER-Net observations report
  54. IBAS Alert n. 9366 not a GRB
  55. Integral GRB210829.14: Global MASTER-Net observations report
  56. GRB 210827A: Fermi GBM Observation
  57. GRB 210826A: AstroSat CZTI detection
  58. Fermi GRB 210827A: Global MASTER-Net observations report
  59. Fermi GRB 210827B: Global MASTER-Net observations report
  60. GRB 210827A: Swift-XRT observations
  61. GRB 210827A: Swift ToO observations
  62. GRB 210827A: Swift/BAT-GUANO detection and arcminute localization
  63. GRB 210820A: CAHA 2.2m Optical Detection
  64. GRB 210824A: Swift/UVOT Upper Limits
  65. GRB 210826A: Swift/UVOT Upper Limits
  66. POLAR detection of a SGR-like burst
  67. GRB 210827B: BALROG localization (Fermi Trigger 651751821 / GRB 210827424)
  68. GRB 210827B: Fermi GBM Final Real-time Localization
  69. GRB 210826A: Swift-XRT observations
  70. GRB 210827A: Fermi GBM Final Real-time Localization
  71. GRB 210822A: CAHA 2.2m observations
  72. GRB 210824A: Swift-BAT refined analysis
  73. GRB 210826A: Fermi-LAT detection
  74. Fermi GRB 210826A: Global MASTER-Net observations report
  75. GRB 210826A: Tiled Swift observations
  76. GRB 210824A: MITSuME Akeno optical upper limits
  77. GRB 210826A: BALROG localization (Fermi Trigger 651654110 / GRB 210826293)
  78. GRB 210826A: Fermi GBM Final Real-time Localization
  79. Swift GRB210825.29: Global MASTER-Net observations report
  80. GRB 210822A: TSHAO continued optical observation
  81. GRB 210822A: VLA detection
  82. GRB 210822A: TSHAO optical observation
  83. Swift detection of an outburst from SGR Swift J1555.2-5402
  84. GRB 210822A: Swift/UVOT Detection
  85. Swift GRB 210824A: Global MASTER-Net observations report
  86. GRB 210824A: BOOTES-5/JGT optical upper limit
  87. GRB 210824A: Fermi GBM Observation
  88. Fermi GRB 210824A: Global MASTER-Net observations report
  89. GRB 210824A: Nanshan/NEXT optical upper limit
  90. GRB 210824A: Swift-XRT refined Analysis
  91. GRB 210822A: GROND observations
  92. GRB 210824A: Enhanced Swift-XRT position
  93. GRB 210822A: Abbey Ridge Observatory optical afterglow observation
  94. GRB 210824A: Swift detection of a burst
  95. GRB 210824A: Fermi GBM Final Real-time Localization
  96. GRB 210822B: DDOTI Upper Limits on the Afterglow
  97. GRB 210822A: Detection by GRBAlpha
  98. GRB 210822A: GECAM refined analysis
  99. GRB 210820A: GROND observations
  100. Konus-Wind detection of GRB 210822A

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