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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"

36311 results found.

  1. GRB 250521A: GRBAlpha detection
  2. GRB 250520A: GRBAlpha detection
  3. GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602)
  4. GRB 250523A: Fermi GBM Final Real-time Localization
  5. GRB 250521B: SVOM/VT optical upper limit
  6. Fermi GRB 250522B: Global MASTER-Net observations report
  7. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  8. GRB 250522B: Fermi GBM Final Localization
  9. GRB 250521D: SVOM/VT optical observations
  10. GRB 250522A: Fermi GBM Final Real-time Localization
  11. Fermi GRB 250521D: Global MASTER-Net observations report
  12. GRB 250521D: DDOTI Optical Upper Limit
  13. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  14. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  15. GRB 250521D: LAST tentative optical counterpart candidate
  16. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  17. GRB 250520A: 10 GHz VLA radio source
  18. GRB 250521B: Swift ToO observations
  19. GRB 250521D: Fermi GBM Final Real-time Localization
  20. GRB 250521C: Fermi GBM Final Localization
  21. GRB 250521A: DDOTI Optical Upper Limit
  22. GRB 250521B: SVOM detection of a burst through offline search
  23. Konus-Wind detection of GRB 250520A (short/hard)
  24. GRB 250520A: VLT/FORS2 Optical Observation
  25. GRB 250502A: Tautenburg observations
  26. GRB 250520A: Swift/UVOT Upper Limits
  27. GRB 250521A: Fermi GBM Final Real-time Localization
  28. Konus-Wind detection of GRB 250516B
  29. IPN triangulation of GRB 250516B
  30. GRB 250520A: J-band observations with WINTER
  31. GRB 250520A: Gemini-South optical observations
  32. GRB 250520A: Swift-XRT refined Analysis
  33. GRB 250520A: REM optical/NIR early observations
  34. GRB 250520B: Fermi GBM Final Real-time Localization
  35. GRB 250520A：SVOM/VT optical candidate
  36. GRB 250520A: COLIBRÍ optical upper limit
  37. GRB 250520A: DDOTI Optical Upper Limit
  38. GRB 250520A: AstroSat CZTI detection of a short burst
  39. GRB 250516B: GRBAlpha detection
  40. GRB 250520A: SVOM/GRM observation
  41. GRB 250520A: Enhanced Swift-XRT position
  42. GRB 250520A: GOTO optical upper limit
  43. GRB 250520A: Prompt enhanced Swift-XRT position
  44. GRB 250520A: Swift detection of a burst
  45. Swift GRB 250520A: Global MASTER-Net observations report
  46. GRB 250516B: Insight-HXMT detection
  47. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  48. GRB 250516A: Swift-BAT refined analysis
  49. GRB 250516A: COLIBRÍ optical upper limit
  50. Konus-Wind detection of GRB 250516A
  51. GRB 250516B: NuSTAR Detection of the Prompt Emission
  52. Fermi GRB 250516A: Global MASTER-Net observations report
  53. GRB 250515A: Swift-XRT observations
  54. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  55. Fermi Gamma-ray Burst Monitor trigger 769160489/250517320 is not a GRB
  56. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  57. Swift GRB 250516A: Global MASTER-Net observations report
  58. GRB 250515A: 1.6m Mephisto optical detection
  59. GRB 250516A: AstroSat CZTI detection
  60. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  61. GRB 250516A: Fermi GBM Observation
  62. GRB 250516A: Swift-XRT refined Analysis
  63. GRB 250516A: Swift/UVOT Detection
  64. GRB 250515A: Swift ToO observations
  65. GRB 250516B: GECAM-B detection of a bright long burst
  66. GRB 250516A: Enhanced Swift-XRT position
  67. GRB 250516A: Swift detection of a burst
  68. GRB 250516A: Fermi GBM Final Real-time Localization
  69. GRB 250512B / EP250512a: SVOM/GRM analysis
  70. GRB 250515A: GOTO candidate optical counterpart
  71. GRB 250515A: Fermi GBM Final Localization
  72. GRB 250424A: COLIBRÍ detection of the associated supernova
  73. Konus-Wind detection of GRB 250512B / EP250512a
  74. GRB 250502A: TESS observations
  75. GRB 250511A: GECAM-A detection of a short burst
  76. GRB 250509A: Swift-BAT refined analysis
  77. Fermi GRB 250512A: Global MASTER-Net observations report
  78. Konus-Wind detection of GRB 250506A
  79. EP250512a/GRB 250512B: REM optical/NIR observations
  80. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  81. GRB 250507B: AstroSat CZTI detection
  82. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  83. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  84. GRB 250512B/EP250512a: SVOM/VT optical fading
  85. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  86. GRB 250507B: GRBAlpha detection
  87. GRB 250506A: GRBAlpha detection
  88. GRB 250512B: SVOM detection of a burst
  89. GRB 250507B: SVOM/GRM observation of a burst
  90. GRB 250512A: Fermi GBM Final Real-time Localization
  91. EP250511a: REM optical/NIR observations
  92. EP250511a: BOOTES-5 optical upper limit
  93. GRB 250510B: Fermi GBM Observation
  94. Fermi GRB 250510C: Global MASTER-Net observations report
  95. Fermi GRB 250510B: Global MASTER-Net observations report
  96. GRB 250510C: Fermi GBM Final Real-time Localization
  97. GRB 250510A: Swift-XRT observations
  98. GRB 250509A: Fermi GBM Observation
  99. GRB 250510A: follow-up observation with EP-FXT
  100. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst

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