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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"

28233 results found.

  1. Konus-Wind detection of GRB 260101A
  2. GRB 260111A: Swift-XRT observations
  3. Swift Trigger 1439093: is probably not GRB 260113A
  4. GRB 260111A: COLIBRÍ optical afterglow candidate
  5. GRB 260111A: Fermi GBM Observation
  6. GRB 251230A: Mondy Optical Observations
  7. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  8. IceCube Alert 260111A: Global MASTER-Net observations report
  9. EP260110a: Global MASTER-Net observations report
  10. Fermi GRB 260111A: Global MASTER-Net observations report
  11. Swift trigger 1436759 is not an astrophysical event
  12. EP260110a: KAIT optical upper limit
  13. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  14. EP 260110a: COLIBRÍ optical observations
  15. EP260110a: SVOM/C-GFT upper limit
  16. EP260110a: Einstein Probe detection of an X-ray transient
  17. GRB 260109C: LCO optical upper limits
  18. GRB 260109C: Kilonova-Catcher optical upper limit
  19. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  20. Swift Trigger 1434591: possible GRB 260109C
  21. GRB 260102A: Swift-XRT afterglow detection
  22. GRB 260104A: Swift-BAT refined analysis
  23. GRB 260101A: Swift-BAT refined analysis
  24. Swift GRB 251230A: Global MASTER-Net OT detection
  25. Fermi GRB 260107A: Global MASTER-Net observations report
  26. GRB 260102A: AbAO optical observations
  27. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  28. Fermi GRB 260105A: Global MASTER-Net observations report
  29. GRB 260105B: Fermi GBM Detection
  30. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  31. GRB 260105A: SVOM/GRM observation
  32. GRB 260105B: SVOM/GRM observation
  33. FRB 20251229A: COLIBRÍ optical upper limits
  34. Fermi GRB 260105B: Global MASTER-Net observations report
  35. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  36. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  37. EP260105a: LCO Optical Upper limit
  38. EP260104a: Global MASTER-Net observations report
  39. EP260104a: Einstein Probe detection of a fast X-ray transient
  40. GRB 260101A: COLIBRÍ optical upper limits
  41. EP260105a: Global MASTER-Net observations report
  42. EP260105a: Einstein Probe detection of an X-ray transient
  43. GRB 260104A: COLIBRÍ optical upper limits
  44. Fermi GRB 260104B: Global MASTER-Net observations report
  45. Swift GRB 260104A: Global MASTER-Net observations report
  46. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  47. GRB 260104A: Swift-XRT refined Analysis
  48. GRB 260104A: Enhanced Swift-XRT position
  49. GRB 260101A: Swift/UVOT Detection
  50. GRB 260103A: GECAM-B observation of a burst
  51. GRB 260104A: Swift detection of a burst
  52. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  53. GRB 260101A: COLIBRÍ optical observations
  54. SVOM GRB260103.08: Global MASTER-Net observations report
  55. SVOM GRB260102A: Global MASTER-Net observations report
  56. Fermi GBM Sub-Threshold Detection of GRB 260102A
  57. GRB 260102A: EP-FXT follow-up observation
  58. EP260101a: Global MASTER-Net observations report
  59. GRB 260102A: LCO optical upper limits
  60. GRB 260102A: Swift-XRT observations
  61. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  62. GRB 260101A: Fermi GBM Observation
  63. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  64. GRB 260102A: SVOM detection of a burst
  65. GRB 260101A: NOT spectroscopic observations
  66. GRB 260101A: SVOM/GRM observation
  67. GRB 260101A: Swift-XRT refined Analysis
  68. Swift GRB 260101A: Global MASTER-Net observations report
  69. GRB 260101A: Enhanced Swift-XRT position
  70. EP260101a: Einstein Probe detection of an X-ray transient
  71. GRB 260101A: LCO detection of the optical counterpart
  72. GRB 260101A: Swift detection of a burst with an optical counterpart
  73. GRB 260101A: Fermi GBM Final Real-time Localization
  74. SVOM GRB251231.57: Global MASTER-Net observations report
  75. GRB 251230A: GRANDMA/TAROT Early Detection
  76. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  77. EP251229a: Optical upper limit with Kinder observations
  78. GRB 251230A: 1.3m DFOT optical upper limit
  79. GRB 251230A: Swift-XRT refined Analysis
  80. GRB 251222A: Mondy Optical Observations
  81. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  82. GRB 251230A: Swift/UVOT detection
  83. GRB251230A: 7DT optical upper limits
  84. GRB 251230A: GOTO optical upper limit
  85. EP251229a: NOT optical upper limits
  86. GRB 251230A / EP251230a: SVOM/VT optical observation
  87. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  88. GRB 251230A: Enhanced Swift-XRT position
  89. GRB 251230A: Early optical counterpart detection by LCO.
  90. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  91. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  92. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  93. Swift GRB 251230A: Global MASTER-Net observations report
  94. EP251229a: Global MASTER-Net observations report
  95. EP251229a: Einstein Probe detection of an X-ray transient
  96. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  97. GRB 251226A: Glowbug gamma-ray detection
  98. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  99. Fermi GRB 251228A: Global MASTER-Net observations report
  100. GRB 251226A: SVOM/GRM observation

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