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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

27292 results found.

  1. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  2. GRB 260112A: Fermi GBM Final Real-time Localization
  3. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  4. GRB 260111A: Fermi GBM Final Real-time Localization
  5. Swift trigger 1436759 is not an astrophysical event
  6. EP260110a: BOOTES-5/JGU optical upper limit
  7. EP260110a: Einstein Probe detection of an X-ray transient
  8. GRB 260109C: LCO optical upper limits
  9. GRB 260109C: Kilonova-Catcher optical upper limit
  10. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  11. Swift Trigger 1434591: possible GRB 260109C
  12. GRB 260109B: Fermi GBM Final Real-time Localization
  13. GRB 260102A: Swift-XRT afterglow detection
  14. GRB 260109A: Fermi GBM Final Real-time Localization
  15. GRB 260104A: Swift-BAT refined analysis
  16. GRB 260101A: Swift-BAT refined analysis
  17. Swift GRB 251230A: Global MASTER-Net OT detection
  18. GRB 260107A: Fermi GBM Final Real-time Localization
  19. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  20. GRB 260105B: Fermi GBM Detection
  21. EP260105a: FTW optical observations
  22. EP260104a: FTW optical observations
  23. GRB 260105B: Fermi GBM Final Real-time Localization
  24. GRB 260105A: Fermi GBM Final Real-time Localization
  25. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  26. EP260104a: Einstein Probe detection of a fast X-ray transient
  27. GRB 260101A: COLIBRÍ optical upper limits
  28. EP260105a: Einstein Probe detection of an X-ray transient
  29. GRB 260103A: Insight-HXMT/HE detection
  30. GRB 260104C: Fermi GBM Final Real-time Localization
  31. Swift GRB 260104A: Global MASTER-Net observations report
  32. GRB 260104A: Swift-XRT refined Analysis
  33. GRB 260104A: Enhanced Swift-XRT position
  34. GRB 260101A: Swift/UVOT Detection
  35. GRB 260104B: Fermi GBM Final Localization
  36. GRB 260104A: Swift detection of a burst
  37. GRB 260102B: Fermi GBM Final Real-time Localization
  38. Fermi GBM Sub-Threshold Detection of GRB 260102A
  39. GRB 260102A: LCO optical upper limits
  40. GRB 260102A: Swift-XRT observations
  41. GRB 251230A / EP251230a: GECAM-B detection
  42. GRB 260102A: SVOM/VT optical counterpart
  43. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  44. GRB 260102A: Swift ToO observations
  45. GRB 260101A: Fermi GBM Observation
  46. GRB 260102A: SVOM detection of a burst
  47. GRB 260101A: GECAM-B detection
  48. GRB 260101A: NOT spectroscopic observations
  49. GRB 260101A: SVOM/GRM observation
  50. GRB 260101A: Swift-XRT refined Analysis
  51. Swift GRB 260101A: Global MASTER-Net observations report
  52. GRB 260101A: Enhanced Swift-XRT position
  53. EP260101a: Einstein Probe detection of an X-ray transient
  54. GRB 260101A: LCO detection of the optical counterpart
  55. GRB 260101A: Swift detection of a burst with an optical counterpart
  56. GRB 260101A: Fermi GBM Final Real-time Localization
  57. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  58. GRB 251230A: GRANDMA/TAROT Early Detection
  59. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  60. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  61. EP251229a: Optical upper limit with Kinder observations
  62. GRB 251230A: 1.3m DFOT optical upper limit
  63. GRB 251230A: Swift-XRT refined Analysis
  64. GRB 251231A: Fermi GBM Final Real-time Localization
  65. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  66. GRB 251230A: Swift/UVOT detection
  67. GRB251230A: 7DT optical upper limits
  68. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  69. EP251229a: BOOTES-2 early optical upper limit
  70. GRB 251230A: GOTO optical upper limit
  71. GRB 251230A / EP251230a: SVOM/VT optical observation
  72. GRB 251230A: Enhanced Swift-XRT position
  73. GRB 251230A: Early optical counterpart detection by LCO.
  74. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  75. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  76. Swift GRB 251230A: Global MASTER-Net observations report
  77. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  78. EP251229a: Einstein Probe detection of an X-ray transient
  79. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  80. GRB 251226A: Glowbug gamma-ray detection
  81. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  82. GRB 251228A: Fermi GBM Final Real-time Localization
  83. GRB 251226A: GECAM-B detection
  84. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 251222A/EP251222b: Optical detection with Kinder observations
  86. EP251222a: Optical upper limit with Kinder observations
  87. GRB 251221A: Swift-BAT refined analysis
  88. GRB 251205A: Kilonova-Catcher optical afterglow detection
  89. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  90. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  91. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  92. GRB 251222A: Continued 1.3m DFOT optical observation
  93. EP251220a: 3.6m DOT optical afterglow detection
  94. GRB 251222A: Fermi GBM Observation
  95. Konus-Wind detection of GRB 251222A / EP251222b
  96. GRB 251222A: Swift-XRT afterglow detection
  97. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  98. GRB 251222A / EP251222b: GOTO optical counterpart detection
  99. GRB 251222A: 1.3m DFOT optical detection
  100. GRB251221A: 7DT optical upper limits

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