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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

27215 results found.

  1. Fermi GRB 250522B: Global MASTER-Net observations report
  2. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  3. GRB 250522B: Fermi GBM Final Localization
  4. GRB 250521D: SVOM/VT optical observations
  5. GRB 250522A: Fermi GBM Final Real-time Localization
  6. EP#01709176612: Swift-XRT counterpart detection of flaring star
  7. Fermi GRB 250521D: Global MASTER-Net observations report
  8. Fermi trigger No 769533898: Global MASTER-Net observations report
  9. Fermi trigger No 769499303: Global MASTER-Net observations report
  10. GRB 250521D: DDOTI Optical Upper Limit
  11. The EP-WXT trigger 01709176612 is likely a flaring star
  12. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  13. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. GRB 250521D: LAST tentative optical counterpart candidate
  15. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  16. GRB 250521D: Fermi GBM Final Real-time Localization
  17. GRB 250521C: Fermi GBM Final Localization
  18. GRB 250521A: DDOTI Optical Upper Limit
  19. GRB 250521B: SVOM detection of a burst through offline search
  20. GRB 250520A: VLT/FORS2 Optical Observation
  21. GRB 250502A: Tautenburg observations
  22. GRB 250520A: Swift/UVOT Upper Limits
  23. GRB 250521A: Fermi GBM Final Real-time Localization
  24. GRB 250520A: Swift-XRT refined Analysis
  25. GRB 250520A: REM optical/NIR early observations
  26. GRB 250520B: Fermi GBM Final Real-time Localization
  27. GRB 250520A：SVOM/VT optical candidate
  28. GRB 250520A: COLIBRÍ optical upper limit
  29. GRB 250520A: DDOTI Optical Upper Limit
  30. GRB 250520A: AstroSat CZTI detection of a short burst
  31. GRB 250516B: GRBAlpha detection
  32. GRB 250520A: SVOM/GRM observation
  33. GRB 250520A: GOTO optical upper limit
  34. GRB 250520A: Swift detection of a burst
  35. Swift GRB 250520A: Global MASTER-Net observations report
  36. GRB 250516A: Swift-BAT refined analysis
  37. GRB 250516A: COLIBRÍ optical upper limit
  38. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  39. Fermi GRB 250516A: Global MASTER-Net observations report
  40. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  41. Fermi Gamma-ray Burst Monitor trigger 769160489/250517320 is not a GRB
  42. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  43. Swift GRB 250516A: Global MASTER-Net observations report
  44. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  45. GRB 250516A: Fermi GBM Observation
  46. GRB 250516A: Swift-XRT refined Analysis
  47. GRB 250516A: Swift/UVOT Detection
  48. GRB 250516B: GECAM-B detection of a bright long burst
  49. GRB 250516A: Swift detection of a burst
  50. GRB 250516A: Fermi GBM Final Real-time Localization
  51. GRB 250512B / EP250512a: SVOM/GRM analysis
  52. GRB 250515A: GOTO candidate optical counterpart
  53. MAXI GRB250515.65: Global MASTER-Net observations report
  54. GRB 250515A: Fermi GBM Final Localization
  55. GRB 250424A: COLIBRÍ detection of the associated supernova
  56. GRB 250502A: TESS observations
  57. Fermi trigger No 768922089: Global MASTER-Net observations report
  58. GRB 250511A: GECAM-A detection of a short burst
  59. GRB 250509A: Swift-BAT refined analysis
  60. Fermi GRB 250512A: Global MASTER-Net observations report
  61. EP250512a/GRB 250512B: REM optical/NIR observations
  62. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  63. EP250511a: Gemini optical counterpart observation
  64. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  65. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  66. EP250512a: Global MASTER-Net observations report
  67. EP250511a: FTW optical and NIR observations
  68. GRB 250512B/EP250512a: SVOM/VT optical fading
  69. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  70. EP250511a: Mephisto optical upper limits
  71. GRB 250507B: GRBAlpha detection
  72. GRB 250512B: SVOM detection of a burst
  73. GRB 250507B: SVOM/GRM observation of a burst
  74. EP250512a: Einstein Probe detection of an X-ray transient
  75. GRB 250512A: Fermi GBM Final Real-time Localization
  76. EP250511a: REM optical/NIR observations
  77. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  78. EP250511a: SVOM/VT optical candidate comfirmation
  79. EP250511a: Global MASTER-Net observations report
  80. EP250511a: COLIBRÍ optical counterpart candidate
  81. EP250511a: Einstein Probe detection of an X-ray transient
  82. EP250508a: Gemini NIR upper limits
  83. GRB 250510B: Fermi GBM Observation
  84. Fermi GRB 250510C: Global MASTER-Net observations report
  85. Fermi GRB 250510B: Global MASTER-Net observations report
  86. GRB 250510C: Fermi GBM Final Real-time Localization
  87. GRB 250510A: Swift-XRT observations
  88. GRB 250509A: Fermi GBM Observation
  89. GRB 250510A: follow-up observation with EP-FXT
  90. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  91. GRB 250510B: Fermi GBM Final Localization
  92. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. GRB 250509A: Swift-XRT refined Analysis
  94. GRB 250510A: SVOM possible detection of a burst
  95. EP250508a: SVOM/VT optical candidate fading
  96. Fermi GRB 250509A: Global MASTER-Net observations report
  97. Swift GRB 250509A: Global MASTER-Net observations report
  98. GRB 250509A: Swift detection of a burst
  99. GRB 250509A: Fermi GBM Final Real-time Localization
  100. GRB 250506A: NOT optical upper limits

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