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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"

43077 results found.

  1. GRB 250520A: 10 GHz VLA Afterglow Confirmation
  2. Fermi GRB 250523A: Global MASTER-Net observations report
  3. Fermi trigger No 769611916: Global MASTER-Net observations report
  4. EP-WXT trigger 01709176712: GOTO observations confirm stellar counterpart variability
  5. GRB 250521A: GRBAlpha detection
  6. GRB 250520A: GRBAlpha detection
  7. GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602)
  8. GRB 250523A: Fermi GBM Final Real-time Localization
  9. The EP-WXT trigger 01709176712 is likely a flaring star
  10. GRB 250521B: SVOM/VT optical upper limit
  11. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  12. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  13. Fermi GRB 250522B: Global MASTER-Net observations report
  14. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  15. GRB 250522B: Fermi GBM Final Localization
  16. GRB 250521D: SVOM/VT optical observations
  17. GRB 250522A: Fermi GBM Final Real-time Localization
  18. EP#01709176612: Swift-XRT counterpart detection of flaring star
  19. Fermi GRB 250521D: Global MASTER-Net observations report
  20. Fermi trigger No 769533898: Global MASTER-Net observations report
  21. Fermi trigger No 769499303: Global MASTER-Net observations report
  22. GRB 250521D: DDOTI Optical Upper Limit
  23. The EP-WXT trigger 01709176612 is likely a flaring star
  24. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  25. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  26. GRB 250521D: LAST tentative optical counterpart candidate
  27. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  28. GRB 250520A: 10 GHz VLA radio source
  29. GRB 250521B: Swift ToO observations
  30. GRB 250521D: Fermi GBM Final Real-time Localization
  31. GRB 250521C: Fermi GBM Final Localization
  32. GRB 250521A: DDOTI Optical Upper Limit
  33. GRB 250521B: SVOM detection of a burst through offline search
  34. Konus-Wind detection of GRB 250520A (short/hard)
  35. GRB 250520A: VLT/FORS2 Optical Observation
  36. GRB 250520A: Swift/UVOT Upper Limits
  37. GRB 250521A: Fermi GBM Final Real-time Localization
  38. Konus-Wind detection of GRB 250516B
  39. IPN triangulation of GRB 250516B
  40. GRB 250520A: J-band observations with WINTER
  41. GRB 250520A: Gemini-South optical observations
  42. GRB 250520A: Swift-XRT refined Analysis
  43. GRB 250520A: REM optical/NIR early observations
  44. GRB 250520B: Fermi GBM Final Real-time Localization
  45. GRB 250520A：SVOM/VT optical candidate
  46. GRB 250520A: COLIBRÍ optical upper limit
  47. GRB 250520A: DDOTI Optical Upper Limit
  48. GRB 250520A: AstroSat CZTI detection of a short burst
  49. GRB 250516B: GRBAlpha detection
  50. GRB 250520A: SVOM/GRM observation
  51. GRB 250520A: Enhanced Swift-XRT position
  52. GRB 250520A: GOTO optical upper limit
  53. GRB 250520A: Prompt enhanced Swift-XRT position
  54. GRB 250520A: Swift detection of a burst
  55. Swift GRB 250520A: Global MASTER-Net observations report
  56. GRB 250516B: Insight-HXMT detection
  57. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  58. GRB 250516A: Swift-BAT refined analysis
  59. GRB 250516A: COLIBRÍ optical upper limit
  60. Konus-Wind detection of GRB 250516A
  61. GRB 250516B: NuSTAR Detection of the Prompt Emission
  62. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  63. Fermi GRB 250516A: Global MASTER-Net observations report
  64. GRB 250515A: Swift-XRT observations
  65. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  66. Fermi Gamma-ray Burst Monitor trigger 769160489/250517320 is not a GRB
  67. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  68. Swift GRB 250516A: Global MASTER-Net observations report
  69. GRB 250515A: 1.6m Mephisto optical detection
  70. GRB 250516A: AstroSat CZTI detection
  71. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  72. GRB 250516A: Fermi GBM Observation
  73. GRB 250516A: Swift-XRT refined Analysis
  74. GRB 250516A: Swift/UVOT Detection
  75. GRB 250515A: Swift ToO observations
  76. GRB 250516B: GECAM-B detection of a bright long burst
  77. GRB 250516A: Enhanced Swift-XRT position
  78. GRB 250516A: Swift detection of a burst
  79. GRB 250516A: Fermi GBM Final Real-time Localization
  80. GRB 250512B / EP250512a: SVOM/GRM analysis
  81. GRB 250515A: GOTO candidate optical counterpart
  82. MAXI GRB250515.65: Global MASTER-Net observations report
  83. GRB 250515A: Fermi GBM Final Localization
  84. GRB 250424A: COLIBRÍ detection of the associated supernova
  85. Konus-Wind detection of GRB 250512B / EP250512a
  86. GRB 250502A: TESS observations
  87. Fermi trigger No 768922089: Global MASTER-Net observations report
  88. GRB 250511A: GECAM-A detection of a short burst
  89. GRB 250509A: Swift-BAT refined analysis
  90. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  91. Fermi GRB 250512A: Global MASTER-Net observations report
  92. Konus-Wind detection of GRB 250506A
  93. EP250512a/GRB 250512B: REM optical/NIR observations
  94. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  95. GRB 250507B: AstroSat CZTI detection
  96. EP250511a: Gemini optical counterpart observation
  97. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  98. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  99. EP250512a: Global MASTER-Net observations report
  100. EP250511a: FTW optical and NIR observations

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