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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"

37676 results found.

  1. GRB 250520A: Swift/UVOT Upper Limits
  2. GRB 250521A: Fermi GBM Final Real-time Localization
  3. Konus-Wind detection of GRB 250516B
  4. IPN triangulation of GRB 250516B
  5. GRB 250520A: J-band observations with WINTER
  6. GRB 250520A: Gemini-South optical observations
  7. GRB 250520A: Swift-XRT refined Analysis
  8. GRB 250520A: REM optical/NIR early observations
  9. GRB 250520B: Fermi GBM Final Real-time Localization
  10. GRB 250520A：SVOM/VT optical candidate
  11. GRB 250520A: COLIBRÍ optical upper limit
  12. GRB 250520A: DDOTI Optical Upper Limit
  13. GRB 250520A: AstroSat CZTI detection of a short burst
  14. GRB 250516B: GRBAlpha detection
  15. GRB 250520A: SVOM/GRM observation
  16. GRB 250520A: Enhanced Swift-XRT position
  17. GRB 250520A: GOTO optical upper limit
  18. GRB 250520A: Prompt enhanced Swift-XRT position
  19. GRB 250520A: Swift detection of a burst
  20. Swift GRB 250520A: Global MASTER-Net observations report
  21. GRB 250516B: Insight-HXMT detection
  22. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  23. GRB 250516A: Swift-BAT refined analysis
  24. GRB 250516A: COLIBRÍ optical upper limit
  25. Konus-Wind detection of GRB 250516A
  26. GRB 250516B: NuSTAR Detection of the Prompt Emission
  27. Fermi GRB 250516A: Global MASTER-Net observations report
  28. GRB 250515A: Swift-XRT observations
  29. GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
  30. Fermi Gamma-ray Burst Monitor trigger 769160489/250517320 is not a GRB
  31. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  32. Swift GRB 250516A: Global MASTER-Net observations report
  33. GRB 250515A: 1.6m Mephisto optical detection
  34. GRB 250516A: AstroSat CZTI detection
  35. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  36. GRB 250516A: Fermi GBM Observation
  37. GRB 250516A: Swift-XRT refined Analysis
  38. GRB 250516A: Swift/UVOT Detection
  39. GRB 250515A: Swift ToO observations
  40. GRB 250516B: GECAM-B detection of a bright long burst
  41. GRB 250516A: Enhanced Swift-XRT position
  42. GRB 250516A: Swift detection of a burst
  43. GRB 250516A: Fermi GBM Final Real-time Localization
  44. GRB 250512B / EP250512a: SVOM/GRM analysis
  45. GRB 250515A: GOTO candidate optical counterpart
  46. GRB 250515A: Fermi GBM Final Localization
  47. GRB 250424A: COLIBRÍ detection of the associated supernova
  48. Konus-Wind detection of GRB 250512B / EP250512a
  49. GRB 250502A: TESS observations
  50. Fermi trigger No 768922089: Global MASTER-Net observations report
  51. GRB 250511A: GECAM-A detection of a short burst
  52. GRB 250509A: Swift-BAT refined analysis
  53. Fermi GRB 250512A: Global MASTER-Net observations report
  54. Konus-Wind detection of GRB 250506A
  55. EP250512a/GRB 250512B: REM optical/NIR observations
  56. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  57. GRB 250507B: AstroSat CZTI detection
  58. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  59. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  60. GRB 250512B/EP250512a: SVOM/VT optical fading
  61. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  62. GRB 250507B: GRBAlpha detection
  63. GRB 250506A: GRBAlpha detection
  64. GRB 250512B: SVOM detection of a burst
  65. GRB 250507B: SVOM/GRM observation of a burst
  66. GRB 250512A: Fermi GBM Final Real-time Localization
  67. EP250511a: REM optical/NIR observations
  68. GRB 250510B: Fermi GBM Observation
  69. Fermi GRB 250510C: Global MASTER-Net observations report
  70. Fermi GRB 250510B: Global MASTER-Net observations report
  71. GRB 250510C: Fermi GBM Final Real-time Localization
  72. GRB 250510A: Swift-XRT observations
  73. GRB 250509A: Fermi GBM Observation
  74. GRB 250510A: follow-up observation with EP-FXT
  75. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  76. GRB 250510B: Fermi GBM Final Localization
  77. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. GRB 250509A: Swift-XRT refined Analysis
  79. GRB 250510A: SVOM possible detection of a burst
  80. GRB 250507A: J-band observations with WINTER (duplicate submission)
  81. GRB 250507A: J-band observations with WINTER
  82. GRB 250509A: Enhanced Swift-XRT position
  83. GRB 250509A: Prompt enhanced Swift-XRT position
  84. Fermi GRB 250509A: Global MASTER-Net observations report
  85. Swift GRB 250509A: Global MASTER-Net observations report
  86. GRB 250509A: Swift detection of a burst
  87. GRB 250509A: Fermi GBM Final Real-time Localization
  88. GRB 250506A: NOT optical upper limits
  89. EP250508a: KAIT optical upper limit
  90. GRB 250507A: KAIT optical upper limit
  91. GRB 250505B: SVOM/GRM observation of a short burst
  92. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  93. GRB 250506A: GECAM detection
  94. EP250508a: REM optical/NIR observations
  95. GRB 250506A: Swift-XRT afterglow detection
  96. GRB 250506A: SVOM/VT optical upper limit
  97. GRB 250507A: Swift-XRT refined Analysis
  98. GRB 250506A: Swift/UVOT Upper Limits
  99. GRB 250427B : SVOM detection of a burst through offline search
  100. GRB 250507A: follow-up observation with EP-FXT

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