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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"

27927 results found.

  1. GRB 250605A: Swift-BAT refined analysis
  2. EP250610a: SVOM/VT optical upper limit
  3. EP250610a: REM optical/NIR observations
  4. GRB 250609A: Fermi GBM Observation
  5. EP250610a: Swift-XRT counterpart detection
  6. EP250610a: Einstein Probe detection of an X-ray transient
  7. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  8. GRB 250605A: Swift/UVOT Upper Limits
  9. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  10. GRB 250527C: CrAO Optical Upper Limit
  11. GRB 250609A: Fermi GBM Final Real-time Localization
  12. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  13. GRB 250607A: Fermi GBM Final Localization
  14. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  15. GRB 250605A: SVOM/VT optical upper limit
  16. GRB 250605A: Swift-XRT refined Analysis
  17. GRB 250605A: Enhanced Swift-XRT position
  18. GRB 250606A: Fermi GBM Final Real-time Localization
  19. GRB 250602A: GECAM detection
  20. GRB 250605A: LT optical observations
  21. GRB 250605A: Swift detection of a burst
  22. Swift GRB250605.79: Global MASTER-Net observations report
  23. Konus-Wind detection of GRB 250601A
  24. IPN triangulation of GRB 250404B
  25. IPN triangulation of GRB 250529A
  26. GRB 250601A: PRIME H band upper limit.
  27. GRB 250601A: PRIME J band upper limit.
  28. GRB 250601A: VLT/FORS2 Optical Observation
  29. GRB 250601A: Fermi GBM Observation
  30. GRB 250603A: Swift/UVOT Upper Limits
  31. GRB 250603A: Swift-XRT refined Analysis
  32. GRB 250603A: Enhanced Swift-XRT position
  33. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  34. Swift GRB250603.05: Global MASTER-Net observations report
  35. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  36. GRB 250602A: Fermi-LAT detection
  37. GRB 250530C: Swift-BAT refined analysis
  38. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  39. GRB 250601A: Swift/XRT candidate afterglow
  40. GRB 250601A: Swift-XRT observations
  41. GRB 250602A: Fermi GBM Final Real-time Localization
  42. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  43. GRB 250601A: Swift ToO observations
  44. GRB 250601A: Fermi GBM Final Real-time Localization
  45. EP#01709177494: SVOM/VT optical observations
  46. GRB 250531A: Fermi GBM Final Real-time Localization
  47. EP#01709177494: Swift-XRT counterpart detection of known source
  48. GRB 250530C: BOOTES-7 optical upper limit
  49. GRB 250530C: Swift-XRT refined Analysis
  50. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  51. Swift GRB 250530C: Global MASTER-Net observations report
  52. GRB 250530C: Enhanced Swift-XRT position
  53. GRB 250530C: Swift detection of a burst
  54. GRB 250530A: EP-FXT counterpart detection
  55. GRB 250530A: SVOM/VT optical upper limit
  56. GRB 250530B: Fermi GBM Final Real-time Localization
  57. GRB 250530A: Swift-XRT counterpart detection
  58. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  59. GRB 250530A: SVOM detection of a burst
  60. GRB 250527D: CALET Gamma-Ray Burst Monitor detection
  61. GRB 250527C: Swift/UVOT Upper Limits
  62. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  63. EP J1350.0-8622: EP-FXT follow-up observation
  64. GRB 250529B: Fermi GBM Final Real-time Localization
  65. GRB 250527B: Swift-XRT observations
  66. EP-WXT trigger 01709177124: confirmation of a stellar flare by BOOTES-6
  67. GRB 250529A: Fermi GBM Final Real-time Localization
  68. GRB 250521C (short): Zwicky Transient Facility identification of a possible fast optical transient counterpart
  69. GRB 250520A: Swift-BAT refined analysis
  70. GRB 250527C: Swift ToO observations
  71. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  72. GRB 250527B: Tiled Swift observations
  73. GRB 250520A: Gemini-South optical afterglow detection
  74. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  75. GRB 250527A: Fermi GBM Final Localization
  76. EP250526a: Einstein Probe detection of a fast X-ray transient
  77. EP J1350.0-8622: BOOTES-6/DPRT optical upper limit
  78. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  79. GRB 250520A: 3 GHz MeerKAT Detection
  80. GRB 250521A: GRBAlpha detection
  81. GRB 250520A: GRBAlpha detection
  82. GRB 250523A: Fermi GBM Final Real-time Localization
  83. GRB 250521B: SVOM/VT optical upper limit
  84. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  85. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  86. GRB 250522B: Fermi GBM Final Localization
  87. GRB 250522A: Fermi GBM Final Real-time Localization
  88. EP#01709176612: Swift-XRT counterpart detection of flaring star
  89. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB
  90. GRB 250521D: LAST tentative optical counterpart candidate
  91. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  92. GRB 250521B: Swift ToO observations
  93. GRB 250521D: Fermi GBM Final Real-time Localization
  94. GRB 250521C: Fermi GBM Final Localization
  95. GRB 250521B: SVOM detection of a burst through offline search
  96. Konus-Wind detection of GRB 250520A (short/hard)
  97. GRB 250520A: Swift/UVOT Upper Limits
  98. GRB 250521A: Fermi GBM Final Real-time Localization
  99. Konus-Wind detection of GRB 250516B
  100. IPN triangulation of GRB 250516B

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