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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 653022153: Global MASTER-Net observations report
  2. Fermi trigger No 653031163: Global MASTER-Net observations report
  3. Swift GRB210910.42: Global MASTER-Net observations report
  4. Fermi GBM observation of a bright flare in the direction of SGR 1935+2154
  5. Fermi trigger No 653010039: Global MASTER-Net observations report
  6. Konus-Wind detection of the second intermediate flare from SGR 1935+2154
  7. IPN triangulation of a bright burst from SGR 1935+2154
  8. Fermi trigger No 652957973: Global MASTER-Net observations report
  9. Fermi trigger No 652944960: Global MASTER-Net observations report
  10. Fermi trigger No 652981861: Global MASTER-Net observations report
  11. GRB 210826A: further Swift-XRT observations
  12. GRB 210909B: GECAM detection
  13. GECAM observations of a series of bursts from SGR J1935+2154
  14. Swift detection of a burst from SGR Swift J1555.2-5402
  15. Fermi trigger No 652934203: Global MASTER-Net observations report
  16. GECAM observation of a burst from SGR J1935+2154
  17. GECAM observation of a burst from SGR J1935+2154
  18. Fermi trigger No 652927551: Global MASTER-Net observations report
  19. GRB 210619B: Maidanak and Assy optical observations, broken power law parametrization
  20. Fermi trigger No 652911693: Global MASTER-Net observations report
  21. Fermi trigger No 652906639: Global MASTER-Net observations report
  22. Fermi GRB 210909A: Global MASTER-Net observations report
  23. GECAM observation of a burst from SGR J1555.2-5402
  24. GRB 210909A: Fermi GBM Final Real-time Localization
  25. GRB 210905A: Swift/UVOT Upper Limits
  26. GRB 210905A: ATCA detection
  27. GRB 210905A: ALMA detection
  28. GRB 210905A: AstroSat CZTI detection
  29. GRB 210905A, GROND observations
  30. Konus-Wind detection of GRB 210905A
  31. Fermi GBM Sub-Threshold Detection of GRB 210905A
  32. Fermi GBM trigger 652585475 / 210906073 is not a GRB
  33. Fermi trigger No 652585475: Global MASTER-Net observations report
  34. GRB 210905A: Swift-XRT refined Analysis
  35. GRB 210610A: Maidanak and AbAO optical observations
  36. GRB 210827B: GECAM detection
  37. GRB 210905A: DECam Detection
  38. GRB 210905A: REM NIR afterglow detection
  39. GRB 210905A: VLT/X-shooter spectroscopic redshift
  40. GRB 210905A: Continued LCO Optical Observations
  41. GRB 210905A: LCO Optical Detection
  42. GRB 210905A: Enhanced Swift-XRT position
  43. GRB 210901A: Swift/UVOT Upper Limits
  44. Swift GRB 210905A: Global MASTER-Net observations report
  45. GRB 210905A: Swift detection of a burst
  46. Fermi GRB 210904A: Global MASTER-Net observations report
  47. GRB 210904A: Fermi GBM Final Real-time Localization
  48. Swift GRB210903.59: Global MASTER-Net observations report
  49. Swift GRB210903.58: Global MASTER-Net observations report
  50. Swift GRB210903.58: Global MASTER-Net observations report
  51. Fermi GRB 210903A: Global MASTER-Net observations report
  52. GRB 210903C: Fermi GBM Final Real-time Localization
  53. GRB 210820A: TSHAO optical upper limit
  54. Fermi GRB 210903B: Global MASTER-Net observations report
  55. GRB 210901A: GROND observations
  56. GRB 210903B: Fermi GBM Final Localization
  57. Fermi GBM observation of a burst from SGR J1555.2-5402
  58. GRB 210903A: Fermi GBM Final Real-time Localization
  59. GRB 210901A: Swift-XRT refined Analysis
  60. GRB 210901A: Swift-BAT refined analysis
  61. GRB 210901A: Enhanced Swift-XRT position
  62. GRB 210901A: LCO Optical Upper Limit
  63. Swift GRB 210901A: Global MASTER-Net observations report
  64. GRB 210901A: Swift detection of a burst
  65. GRB 210827A: further Swift-XRT observations
  66. GRB 210822A: CALET Gamma-Ray Burst Monitor detection
  67. GRB 210827A: Swift/UVOT Upper Limits
  68. GRB 210827A: BOOTES-5/JGT optical upper limit
  69. Integral GRB210829.17: Global MASTER-Net observations report
  70. IBAS Alert n. 9366 not a GRB
  71. Integral GRB210829.14: Global MASTER-Net observations report
  72. GRB 210827A: Fermi GBM Observation
  73. GRB 210826A: AstroSat CZTI detection
  74. Fermi GRB 210827A: Global MASTER-Net observations report
  75. Fermi GRB 210827B: Global MASTER-Net observations report
  76. GRB 210827A: Swift-XRT observations
  77. GRB 210827A: Swift ToO observations
  78. GRB 210827A: Swift/BAT-GUANO detection and arcminute localization
  79. GRB 210820A: CAHA 2.2m Optical Detection
  80. GRB 210824A: Swift/UVOT Upper Limits
  81. GRB 210826A: Swift/UVOT Upper Limits
  82. POLAR detection of a SGR-like burst
  83. GRB 210827B: BALROG localization (Fermi Trigger 651751821 / GRB 210827424)
  84. GRB 210827B: Fermi GBM Final Real-time Localization
  85. GRB 210826A: Swift-XRT observations
  86. GRB 210827A: Fermi GBM Final Real-time Localization
  87. GRB 210822A: CAHA 2.2m observations
  88. GRB 210824A: Swift-BAT refined analysis
  89. GRB 210826A: Fermi-LAT detection
  90. Fermi GRB 210826A: Global MASTER-Net observations report
  91. GRB 210826A: Tiled Swift observations
  92. GRB 210824A: MITSuME Akeno optical upper limits
  93. GRB 210826A: BALROG localization (Fermi Trigger 651654110 / GRB 210826293)
  94. GRB 210826A: Fermi GBM Final Real-time Localization
  95. Swift GRB210825.29: Global MASTER-Net observations report
  96. GRB 210822A: TSHAO continued optical observation
  97. GRB 210822A: VLA detection
  98. GRB 210822A: TSHAO optical observation
  99. Swift detection of an outburst from SGR Swift J1555.2-5402
  100. GRB 210822A: Swift/UVOT Detection

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