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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"

28124 results found.

  1. Fermi GRB 260111A: Global MASTER-Net observations report
  2. Swift trigger 1436759 is not an astrophysical event
  3. EP260110a: KAIT optical upper limit
  4. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  5. EP 260110a: COLIBRÍ optical observations
  6. EP260110a: SVOM/C-GFT 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 260102A: Swift-XRT afterglow detection
  13. GRB 260104A: Swift-BAT refined analysis
  14. GRB 260101A: Swift-BAT refined analysis
  15. Swift GRB 251230A: Global MASTER-Net OT detection
  16. Fermi GRB 260107A: Global MASTER-Net observations report
  17. GRB 260102A: AbAO optical observations
  18. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  19. Fermi GRB 260105A: Global MASTER-Net observations report
  20. GRB 260105B: Fermi GBM Detection
  21. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  22. GRB 260105A: SVOM/GRM observation
  23. GRB 260105B: SVOM/GRM observation
  24. FRB 20251229A: COLIBRÍ optical upper limits
  25. Fermi GRB 260105B: Global MASTER-Net observations report
  26. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  27. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  28. EP260105a: LCO Optical Upper limit
  29. EP260104a: Global MASTER-Net observations report
  30. EP260104a: Einstein Probe detection of a fast X-ray transient
  31. GRB 260101A: COLIBRÍ optical upper limits
  32. EP260105a: Global MASTER-Net observations report
  33. EP260105a: Einstein Probe detection of an X-ray transient
  34. GRB 260104A: COLIBRÍ optical upper limits
  35. Fermi GRB 260104B: Global MASTER-Net observations report
  36. Swift GRB 260104A: Global MASTER-Net observations report
  37. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  38. GRB 260104A: Swift-XRT refined Analysis
  39. GRB 260104A: Enhanced Swift-XRT position
  40. GRB 260101A: Swift/UVOT Detection
  41. GRB 260103A: GECAM-B observation of a burst
  42. GRB 260104A: Swift detection of a burst
  43. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  44. GRB 260101A: COLIBRÍ optical observations
  45. SVOM GRB260103.08: Global MASTER-Net observations report
  46. SVOM GRB260102A: Global MASTER-Net observations report
  47. Fermi GBM Sub-Threshold Detection of GRB 260102A
  48. GRB 260102A: EP-FXT follow-up observation
  49. EP260101a: Global MASTER-Net observations report
  50. GRB 260102A: LCO optical upper limits
  51. GRB 260102A: Swift-XRT observations
  52. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  53. GRB 260101A: Fermi GBM Observation
  54. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  55. GRB 260102A: SVOM detection of a burst
  56. GRB 260101A: NOT spectroscopic observations
  57. GRB 260101A: SVOM/GRM observation
  58. GRB 260101A: Swift-XRT refined Analysis
  59. Swift GRB 260101A: Global MASTER-Net observations report
  60. GRB 260101A: Enhanced Swift-XRT position
  61. EP260101a: Einstein Probe detection of an X-ray transient
  62. GRB 260101A: LCO detection of the optical counterpart
  63. GRB 260101A: Swift detection of a burst with an optical counterpart
  64. GRB 260101A: Fermi GBM Final Real-time Localization
  65. SVOM GRB251231.57: Global MASTER-Net observations report
  66. GRB 251230A: GRANDMA/TAROT Early Detection
  67. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  68. EP251229a: Optical upper limit with Kinder observations
  69. GRB 251230A: 1.3m DFOT optical upper limit
  70. GRB 251230A: Swift-XRT refined Analysis
  71. GRB 251222A: Mondy Optical Observations
  72. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  73. GRB 251230A: Swift/UVOT detection
  74. GRB251230A: 7DT optical upper limits
  75. GRB 251230A: GOTO optical upper limit
  76. EP251229a: NOT optical upper limits
  77. GRB 251230A / EP251230a: SVOM/VT optical observation
  78. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  79. GRB 251230A: Enhanced Swift-XRT position
  80. GRB 251230A: Early optical counterpart detection by LCO.
  81. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  82. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  83. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  84. Swift GRB 251230A: Global MASTER-Net observations report
  85. EP251229a: Global MASTER-Net observations report
  86. EP251229a: Einstein Probe detection of an X-ray transient
  87. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  88. GRB 251226A: Glowbug gamma-ray detection
  89. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  90. Fermi GRB 251228A: Global MASTER-Net observations report
  91. GRB 251226A: SVOM/GRM observation
  92. GRB 251226A: GECAM-B detection
  93. SVOM GRB251227.07: Global MASTER-Net observations report
  94. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  95. IceCube Alert 251225.84: Global MASTER-Net observations report
  96. GRB 251222A/EP251222b: Optical detection with Kinder observations
  97. EP251222a: Optical upper limit with Kinder observations
  98. GRB 251221A: Swift-BAT refined analysis
  99. GRB 251205A: Kilonova-Catcher optical afterglow detection
  100. GRB 251222A: AbAO optical observations

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