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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"

43933 results found.

  1. Fermi GRB 250521D: Global MASTER-Net observations report
  2. Fermi trigger No 769533898: Global MASTER-Net observations report
  3. Fermi trigger No 769499303: Global MASTER-Net observations report
  4. GRB 250521D: DDOTI Optical Upper Limit
  5. The EP-WXT trigger 01709176612 is likely a flaring star
  6. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  7. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  8. GRB 250521D: LAST tentative optical counterpart candidate
  9. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  10. GRB 250520A: 10 GHz VLA radio source
  11. GRB 250521B: Swift ToO observations
  12. GRB 250521D: Fermi GBM Final Real-time Localization
  13. GRB 250521C: Fermi GBM Final Localization
  14. GRB 250521A: DDOTI Optical Upper Limit
  15. GRB 250521B: SVOM detection of a burst through offline search
  16. Konus-Wind detection of GRB 250520A (short/hard)
  17. GRB 250520A: VLT/FORS2 Optical Observation
  18. GRB 250502A: Tautenburg observations
  19. GRB 250520A: Swift/UVOT Upper Limits
  20. GRB 250521A: Fermi GBM Final Real-time Localization
  21. Konus-Wind detection of GRB 250516B
  22. IPN triangulation of GRB 250516B
  23. GRB 250520A: J-band observations with WINTER
  24. GRB 250520A: Gemini-South optical observations
  25. GRB 250520A: Swift-XRT refined Analysis
  26. GRB 250520A: REM optical/NIR early observations
  27. GRB 250520B: Fermi GBM Final Real-time Localization
  28. GRB 250520A：SVOM/VT optical candidate
  29. GRB 250520A: COLIBRÍ optical upper limit
  30. GRB 250520A: DDOTI Optical Upper Limit
  31. GRB 250520A: AstroSat CZTI detection of a short burst
  32. GRB 250516B: GRBAlpha detection
  33. GRB 250520A: SVOM/GRM observation
  34. GRB 250520A: Enhanced Swift-XRT position
  35. GRB 250520A: GOTO optical upper limit
  36. GRB 250520A: Prompt enhanced Swift-XRT position
  37. GRB 250520A: Swift detection of a burst
  38. Swift GRB 250520A: Global MASTER-Net observations report
  39. GRB 250516B: Insight-HXMT detection
  40. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  41. GRB 250516A: Swift-BAT refined analysis
  42. GRB 250516A: COLIBRÍ optical upper limit
  43. Konus-Wind detection of GRB 250516A
  44. GRB 250516B: NuSTAR Detection of the Prompt Emission
  45. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  46. Fermi GRB 250516A: Global MASTER-Net observations report
  47. GRB 250515A: Swift-XRT observations
  48. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  49. Fermi Gamma-ray Burst Monitor trigger 769160489/250517320 is not a GRB
  50. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  51. Swift GRB 250516A: Global MASTER-Net observations report
  52. GRB 250515A: 1.6m Mephisto optical detection
  53. GRB 250516A: AstroSat CZTI detection
  54. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  55. GRB 250516A: Fermi GBM Observation
  56. GRB 250516A: Swift-XRT refined Analysis
  57. GRB 250516A: Swift/UVOT Detection
  58. GRB 250515A: Swift ToO observations
  59. GRB 250516B: GECAM-B detection of a bright long burst
  60. GRB 250516A: Enhanced Swift-XRT position
  61. GRB 250516A: Swift detection of a burst
  62. GRB 250516A: Fermi GBM Final Real-time Localization
  63. GRB 250512B / EP250512a: SVOM/GRM analysis
  64. GRB 250515A: GOTO candidate optical counterpart
  65. MAXI GRB250515.65: Global MASTER-Net observations report
  66. GRB 250515A: Fermi GBM Final Localization
  67. GRB 250424A: COLIBRÍ detection of the associated supernova
  68. Konus-Wind detection of GRB 250512B / EP250512a
  69. GRB 250502A: TESS observations
  70. Fermi trigger No 768922089: Global MASTER-Net observations report
  71. GRB 250511A: GECAM-A detection of a short burst
  72. GRB 250509A: Swift-BAT refined analysis
  73. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  74. Fermi GRB 250512A: Global MASTER-Net observations report
  75. Konus-Wind detection of GRB 250506A
  76. EP250512a/GRB 250512B: REM optical/NIR observations
  77. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  78. GRB 250507B: AstroSat CZTI detection
  79. EP250511a: Gemini optical counterpart observation
  80. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  81. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  82. EP250512a: Global MASTER-Net observations report
  83. EP250511a: FTW optical and NIR observations
  84. GRB 250512B/EP250512a: SVOM/VT optical fading
  85. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  86. EP250511a: Mephisto optical upper limits
  87. GRB 250507B: GRBAlpha detection
  88. GRB 250506A: GRBAlpha detection
  89. GRB 250512B: SVOM detection of a burst
  90. GRB 250507B: SVOM/GRM observation of a burst
  91. EP250512a: Einstein Probe detection of an X-ray transient
  92. GRB 250512A: Fermi GBM Final Real-time Localization
  93. EP250511a: REM optical/NIR observations
  94. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  95. EP250511a: SVOM/VT optical candidate comfirmation
  96. EP250511a: Global MASTER-Net observations report
  97. EP250511a: COLIBRÍ optical counterpart candidate
  98. EP250511a: BOOTES-5 optical upper limit
  99. EP250511a: Einstein Probe detection of an X-ray transient
  100. EP250508a: Gemini NIR upper limits

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