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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"

26921 results found.

  1. The EP-WXT trigger 01709251266 is likely a flaring star
  2. Swift Trigger 1434591 is not a GRB
  3. GRB 260111A: GOTO optical upper limits
  4. GRB 260112B: Fermi GBM Final Real-time Localization
  5. GRB 251230A: Mondy Optical Observations
  6. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  7. GRB 260112A: Fermi GBM Final Real-time Localization
  8. EP260110a: SVOM/VT optical upper limits
  9. IceCube Alert 260111A: Global MASTER-Net observations report
  10. EP260110a: Global MASTER-Net observations report
  11. Fermi GRB 260111A: Global MASTER-Net observations report
  12. GRB 260111A: Fermi GBM Final Real-time Localization
  13. Swift trigger 1436759 is not an astrophysical event
  14. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  15. EP 260110a: COLIBRÍ optical observations
  16. EP260110a: SVOM/C-GFT upper limit
  17. EP260110a: Einstein Probe detection of an X-ray transient
  18. GRB 260109C: LCO optical upper limits
  19. GRB 260109C: Kilonova-Catcher optical upper limit
  20. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  21. Swift Trigger 1434591: possible GRB 260109C
  22. GRB 260109B: Fermi GBM Final Real-time Localization
  23. GRB 260109A: Fermi GBM Final Real-time Localization
  24. GRB 260104A: Swift-BAT refined analysis
  25. GRB 260101A: Swift-BAT refined analysis
  26. Swift GRB 251230A: Global MASTER-Net OT detection
  27. Fermi GRB 260107A: Global MASTER-Net observations report
  28. GRB 260102A: AbAO optical observations
  29. GRB 260107A: Fermi GBM Final Real-time Localization
  30. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  31. The EP-WXT trigger 01709251112 is likely a flaring star
  32. Fermi GRB 260105A: Global MASTER-Net observations report
  33. GRB 260105B: Fermi GBM Detection
  34. EP260105a: FTW optical observations
  35. EP260104a: FTW optical observations
  36. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  37. GRB 260105A: SVOM/GRM observation
  38. GRB 260105B: SVOM/GRM observation
  39. The EP-WXT trigger 01709251028 is likely a flaring star
  40. Fermi GRB 260105B: Global MASTER-Net observations report
  41. EP260105a: SVOM/VT optical upperlimit
  42. GRB 260105B: Fermi GBM Final Real-time Localization
  43. GRB 260105A: Fermi GBM Final Real-time Localization
  44. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  45. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  46. EP260105a: LCO Optical Upper limit
  47. EP260104a: Global MASTER-Net observations report
  48. EP260104a: Einstein Probe detection of a fast X-ray transient
  49. GRB 260101A: COLIBRÍ optical upper limits
  50. EP260105a: Global MASTER-Net observations report
  51. EP260105a: Einstein Probe detection of an X-ray transient
  52. GRB 260104A: COLIBRÍ optical upper limits
  53. GRB 260104C: Fermi GBM Final Real-time Localization
  54. Fermi GRB 260104B: Global MASTER-Net observations report
  55. Swift GRB 260104A: Global MASTER-Net observations report
  56. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  57. GRB 260104A: Swift-XRT refined Analysis
  58. GRB 260101A: Swift/UVOT Detection
  59. GRB 260103A: GECAM-B observation of a burst
  60. GRB 260104B: Fermi GBM Final Localization
  61. GRB 260104A: Swift detection of a burst
  62. GRB 260103A: SVOM/GRM observation of a possible GRB
  63. GRB 260101A: COLIBRÍ optical observations
  64. SVOM GRB260103.08: Global MASTER-Net observations report
  65. GRB 260102B: Fermi GBM Final Real-time Localization
  66. SVOM GRB260102A: Global MASTER-Net observations report
  67. Fermi GBM Sub-Threshold Detection of GRB 260102A
  68. GRB 260102A: EP-FXT follow-up observation
  69. EP260101a: Global MASTER-Net observations report
  70. GRB 260102A: LCO optical upper limits
  71. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  72. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  73. GRB 251230A / EP251230a: GECAM-B detection
  74. GRB 260102A: SVOM/VT optical counterpart
  75. GRB 260101A: Fermi GBM Observation
  76. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  77. GRB 260102A: SVOM detection of a burst
  78. GRB 260101A: GECAM-B detection
  79. GRB 260101A: NOT spectroscopic observations
  80. GRB 260101A: SVOM/GRM observation
  81. GRB 260101A: Swift-XRT refined Analysis
  82. Swift GRB 260101A: Global MASTER-Net observations report
  83. EP260101a: Einstein Probe detection of an X-ray transient
  84. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  85. GRB 260101A: Swift detection of a burst with an optical counterpart
  86. GRB 260101A: Fermi GBM Final Real-time Localization
  87. SVOM GRB251231.57: Global MASTER-Net observations report
  88. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  89. GRB 251230A: GRANDMA/TAROT Early Detection
  90. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  91. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  92. EP251229a: Optical upper limit with Kinder observations
  93. GRB 251230A: 1.3m DFOT optical upper limit
  94. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  95. GRB 251230A: Swift-XRT refined Analysis
  96. GRB 251231A: Fermi GBM Final Real-time Localization
  97. GRB 251222A: Mondy Optical Observations
  98. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  99. GRB 251230A: Swift/UVOT detection
  100. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2

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