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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"

26922 results found.

  1. GRB 260111A: Fermi GBM Observation
  2. The EP-WXT trigger 01709251266 is likely a flaring star
  3. Swift Trigger 1434591 is not a GRB
  4. GRB 260111A: GOTO optical upper limits
  5. GRB 260112B: Fermi GBM Final Real-time Localization
  6. GRB 251230A: Mondy Optical Observations
  7. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  8. GRB 260112A: Fermi GBM Final Real-time Localization
  9. EP260110a: SVOM/VT optical upper limits
  10. IceCube Alert 260111A: Global MASTER-Net observations report
  11. EP260110a: Global MASTER-Net observations report
  12. Fermi GRB 260111A: Global MASTER-Net observations report
  13. GRB 260111A: Fermi GBM Final Real-time Localization
  14. Swift trigger 1436759 is not an astrophysical event
  15. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  16. EP 260110a: COLIBRÍ optical observations
  17. EP260110a: SVOM/C-GFT upper limit
  18. EP260110a: Einstein Probe detection of an X-ray transient
  19. GRB 260109C: LCO optical upper limits
  20. GRB 260109C: Kilonova-Catcher optical upper limit
  21. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  22. Swift Trigger 1434591: possible GRB 260109C
  23. GRB 260109B: Fermi GBM Final Real-time Localization
  24. GRB 260109A: Fermi GBM Final Real-time Localization
  25. GRB 260104A: Swift-BAT refined analysis
  26. GRB 260101A: Swift-BAT refined analysis
  27. Swift GRB 251230A: Global MASTER-Net OT detection
  28. Fermi GRB 260107A: Global MASTER-Net observations report
  29. GRB 260102A: AbAO optical observations
  30. GRB 260107A: Fermi GBM Final Real-time Localization
  31. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  32. The EP-WXT trigger 01709251112 is likely a flaring star
  33. Fermi GRB 260105A: Global MASTER-Net observations report
  34. GRB 260105B: Fermi GBM Detection
  35. EP260105a: FTW optical observations
  36. EP260104a: FTW optical observations
  37. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  38. GRB 260105A: SVOM/GRM observation
  39. GRB 260105B: SVOM/GRM observation
  40. The EP-WXT trigger 01709251028 is likely a flaring star
  41. Fermi GRB 260105B: Global MASTER-Net observations report
  42. EP260105a: SVOM/VT optical upperlimit
  43. GRB 260105B: Fermi GBM Final Real-time Localization
  44. GRB 260105A: Fermi GBM Final Real-time Localization
  45. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  46. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  47. EP260105a: LCO Optical Upper limit
  48. EP260104a: Global MASTER-Net observations report
  49. EP260104a: Einstein Probe detection of a fast X-ray transient
  50. GRB 260101A: COLIBRÍ optical upper limits
  51. EP260105a: Global MASTER-Net observations report
  52. EP260105a: Einstein Probe detection of an X-ray transient
  53. GRB 260104A: COLIBRÍ optical upper limits
  54. GRB 260104C: Fermi GBM Final Real-time Localization
  55. Fermi GRB 260104B: Global MASTER-Net observations report
  56. Swift GRB 260104A: Global MASTER-Net observations report
  57. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  58. GRB 260104A: Swift-XRT refined Analysis
  59. GRB 260101A: Swift/UVOT Detection
  60. GRB 260103A: GECAM-B observation of a burst
  61. GRB 260104B: Fermi GBM Final Localization
  62. GRB 260104A: Swift detection of a burst
  63. GRB 260103A: SVOM/GRM observation of a possible GRB
  64. GRB 260101A: COLIBRÍ optical observations
  65. SVOM GRB260103.08: Global MASTER-Net observations report
  66. GRB 260102B: Fermi GBM Final Real-time Localization
  67. SVOM GRB260102A: Global MASTER-Net observations report
  68. Fermi GBM Sub-Threshold Detection of GRB 260102A
  69. GRB 260102A: EP-FXT follow-up observation
  70. EP260101a: Global MASTER-Net observations report
  71. GRB 260102A: LCO optical upper limits
  72. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  73. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  74. GRB 251230A / EP251230a: GECAM-B detection
  75. GRB 260102A: SVOM/VT optical counterpart
  76. GRB 260101A: Fermi GBM Observation
  77. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  78. GRB 260102A: SVOM detection of a burst
  79. GRB 260101A: GECAM-B detection
  80. GRB 260101A: NOT spectroscopic observations
  81. GRB 260101A: SVOM/GRM observation
  82. GRB 260101A: Swift-XRT refined Analysis
  83. Swift GRB 260101A: Global MASTER-Net observations report
  84. EP260101a: Einstein Probe detection of an X-ray transient
  85. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  86. GRB 260101A: Swift detection of a burst with an optical counterpart
  87. GRB 260101A: Fermi GBM Final Real-time Localization
  88. SVOM GRB251231.57: Global MASTER-Net observations report
  89. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  90. GRB 251230A: GRANDMA/TAROT Early Detection
  91. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  92. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  93. EP251229a: Optical upper limit with Kinder observations
  94. GRB 251230A: 1.3m DFOT optical upper limit
  95. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  96. GRB 251230A: Swift-XRT refined Analysis
  97. GRB 251231A: Fermi GBM Final Real-time Localization
  98. GRB 251222A: Mondy Optical Observations
  99. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  100. GRB 251230A: Swift/UVOT detection

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