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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"

36215 results found.

  1. GRB 250314A: CIDER NB1008 upper limit
  2. EP J1350.0-8622: BOOTES-6/DPRT optical upper limit
  3. GRB 250520A: 3 GHz MeerKAT Detection
  4. GRB 250520A: 10 GHz VLA Afterglow Confirmation
  5. Fermi GRB 250523A: Global MASTER-Net observations report
  6. GRB 250521A: GRBAlpha detection
  7. GRB 250520A: GRBAlpha detection
  8. GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602)
  9. GRB 250523A: Fermi GBM Final Real-time Localization
  10. GRB 250521B: SVOM/VT optical upper limit
  11. Fermi GRB 250522B: Global MASTER-Net observations report
  12. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  13. GRB 250522B: Fermi GBM Final Localization
  14. GRB 250521D: SVOM/VT optical observations
  15. GRB 250522A: Fermi GBM Final Real-time Localization
  16. Fermi GRB 250521D: Global MASTER-Net observations report
  17. GRB 250521D: DDOTI Optical Upper Limit
  18. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  19. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  20. GRB 250521D: LAST tentative optical counterpart candidate
  21. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  22. GRB 250520A: 10 GHz VLA radio source
  23. GRB 250521B: Swift ToO observations
  24. GRB 250521D: Fermi GBM Final Real-time Localization
  25. GRB 250521C: Fermi GBM Final Localization
  26. GRB 250521A: DDOTI Optical Upper Limit
  27. GRB 250521B: SVOM detection of a burst through offline search
  28. Konus-Wind detection of GRB 250520A (short/hard)
  29. GRB 250520A: VLT/FORS2 Optical Observation
  30. GRB 250502A: Tautenburg observations
  31. GRB 250520A: Swift/UVOT Upper Limits
  32. GRB 250521A: Fermi GBM Final Real-time Localization
  33. Konus-Wind detection of GRB 250516B
  34. IPN triangulation of GRB 250516B
  35. GRB 250520A: J-band observations with WINTER
  36. GRB 250520A: Gemini-South optical observations
  37. GRB 250520A: Swift-XRT refined Analysis
  38. GRB 250520A: REM optical/NIR early observations
  39. GRB 250520B: Fermi GBM Final Real-time Localization
  40. GRB 250520A：SVOM/VT optical candidate
  41. GRB 250520A: COLIBRÍ optical upper limit
  42. GRB 250520A: DDOTI Optical Upper Limit
  43. GRB 250520A: AstroSat CZTI detection of a short burst
  44. GRB 250516B: GRBAlpha detection
  45. GRB 250520A: SVOM/GRM observation
  46. GRB 250520A: Enhanced Swift-XRT position
  47. GRB 250520A: GOTO optical upper limit
  48. GRB 250520A: Prompt enhanced Swift-XRT position
  49. GRB 250520A: Swift detection of a burst
  50. Swift GRB 250520A: Global MASTER-Net observations report
  51. GRB 250516B: Insight-HXMT detection
  52. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  53. GRB 250516A: Swift-BAT refined analysis
  54. GRB 250516A: COLIBRÍ optical upper limit
  55. Konus-Wind detection of GRB 250516A
  56. GRB 250516B: NuSTAR Detection of the Prompt Emission
  57. Fermi GRB 250516A: Global MASTER-Net observations report
  58. GRB 250515A: Swift-XRT observations
  59. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  60. Fermi Gamma-ray Burst Monitor trigger 769160489/250517320 is not a GRB
  61. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  62. Swift GRB 250516A: Global MASTER-Net observations report
  63. GRB 250515A: 1.6m Mephisto optical detection
  64. GRB 250516A: AstroSat CZTI detection
  65. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  66. GRB 250516A: Fermi GBM Observation
  67. GRB 250516A: Swift-XRT refined Analysis
  68. GRB 250516A: Swift/UVOT Detection
  69. GRB 250515A: Swift ToO observations
  70. GRB 250516B: GECAM-B detection of a bright long burst
  71. GRB 250516A: Enhanced Swift-XRT position
  72. GRB 250516A: Swift detection of a burst
  73. GRB 250516A: Fermi GBM Final Real-time Localization
  74. GRB 250512B / EP250512a: SVOM/GRM analysis
  75. GRB 250515A: GOTO candidate optical counterpart
  76. GRB 250515A: Fermi GBM Final Localization
  77. GRB 250424A: COLIBRÍ detection of the associated supernova
  78. Konus-Wind detection of GRB 250512B / EP250512a
  79. GRB 250502A: TESS observations
  80. GRB 250511A: GECAM-A detection of a short burst
  81. GRB 250509A: Swift-BAT refined analysis
  82. Fermi GRB 250512A: Global MASTER-Net observations report
  83. Konus-Wind detection of GRB 250506A
  84. EP250512a/GRB 250512B: REM optical/NIR observations
  85. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  86. GRB 250507B: AstroSat CZTI detection
  87. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  88. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  89. GRB 250512B/EP250512a: SVOM/VT optical fading
  90. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  91. GRB 250507B: GRBAlpha detection
  92. GRB 250506A: GRBAlpha detection
  93. GRB 250512B: SVOM detection of a burst
  94. GRB 250507B: SVOM/GRM observation of a burst
  95. GRB 250512A: Fermi GBM Final Real-time Localization
  96. EP250511a: REM optical/NIR observations
  97. EP250511a: BOOTES-5 optical upper limit
  98. GRB 250510B: Fermi GBM Observation
  99. Fermi GRB 250510C: Global MASTER-Net observations report
  100. Fermi GRB 250510B: Global MASTER-Net observations report

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