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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"

45746 results found.

  1. EP260110a: KAIT optical upper limit
  2. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  3. EP 260110a: COLIBRÍ optical observations
  4. EP260110a: SVOM/C-GFT upper limit
  5. EP260110a: BOOTES-5/JGU optical upper limit
  6. EP260110a: Einstein Probe detection of an X-ray transient
  7. GRB 260109C: LCO optical upper limits
  8. GRB 260109C: Kilonova-Catcher optical upper limit
  9. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  10. Swift Trigger 1434591: possible GRB 260109C
  11. GRB 260109B: Fermi GBM Final Real-time Localization
  12. GRB 260102A: Swift-XRT afterglow detection
  13. GRB 260109A: Fermi GBM Final Real-time Localization
  14. GRB 260104A: Swift-BAT refined analysis
  15. GRB 260101A: Swift-BAT refined analysis
  16. Swift GRB 251230A: Global MASTER-Net OT detection
  17. Fermi GRB 260107A: Global MASTER-Net observations report
  18. GRB 260102A: AbAO optical observations
  19. GRB 260107A: Fermi GBM Final Real-time Localization
  20. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  21. The EP-WXT trigger 01709251112 is likely a flaring star
  22. Fermi GRB 260105A: Global MASTER-Net observations report
  23. GRB 260105B: Fermi GBM Detection
  24. EP260105a: FTW optical observations
  25. EP260104a: FTW optical observations
  26. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  27. GRB 260105A: SVOM/GRM observation
  28. GRB 260105B: SVOM/GRM observation
  29. The EP-WXT trigger 01709251028 is likely a flaring star
  30. FRB 20251229A: COLIBRÍ optical upper limits
  31. Fermi GRB 260105B: Global MASTER-Net observations report
  32. EP260105a: SVOM/VT optical upperlimit
  33. GRB 260105B: Fermi GBM Final Real-time Localization
  34. GRB 260105A: Fermi GBM Final Real-time Localization
  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 260103A: Insight-HXMT/HE detection
  44. GRB 260104A: COLIBRÍ optical upper limits
  45. GRB 260104C: Fermi GBM Final Real-time Localization
  46. Fermi GRB 260104B: Global MASTER-Net observations report
  47. Swift GRB 260104A: Global MASTER-Net observations report
  48. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  49. GRB 260104A: Swift-XRT refined Analysis
  50. GRB 260104A: Enhanced Swift-XRT position
  51. GRB 260101A: Swift/UVOT Detection
  52. GRB 260103A: GECAM-B observation of a burst
  53. GRB 260104B: Fermi GBM Final Localization
  54. GRB 260104A: Swift detection of a burst
  55. GRB 260103A: SVOM/GRM observation of a possible GRB
  56. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  57. GRB 260101A: COLIBRÍ optical observations
  58. SVOM GRB260103.08: Global MASTER-Net observations report
  59. GRB 260102B: Fermi GBM Final Real-time Localization
  60. SVOM GRB260102A: Global MASTER-Net observations report
  61. Fermi GBM Sub-Threshold Detection of GRB 260102A
  62. GRB 260102A: EP-FXT follow-up observation
  63. EP260101a: Global MASTER-Net observations report
  64. GRB 260102A: LCO optical upper limits
  65. GRB 260102A: Swift-XRT observations
  66. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  67. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  68. GRB 251230A / EP251230a: GECAM-B detection
  69. GRB 260102A: SVOM/VT optical counterpart
  70. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  71. GRB 260102A: Swift ToO observations
  72. GRB 260101A: Fermi GBM Observation
  73. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  74. GRB 260102A: SVOM detection of a burst
  75. GRB 260101A: GECAM-B detection
  76. GRB 260101A: NOT spectroscopic observations
  77. GRB 260101A: SVOM/GRM observation
  78. GRB 260101A: Swift-XRT refined Analysis
  79. Swift GRB 260101A: Global MASTER-Net observations report
  80. GRB 260101A: Enhanced Swift-XRT position
  81. EP260101a: Einstein Probe detection of an X-ray transient
  82. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  83. GRB 260101A: LCO detection of the optical counterpart
  84. GRB 260101A: Swift detection of a burst with an optical counterpart
  85. GRB 260101A: Fermi GBM Final Real-time Localization
  86. SVOM GRB251231.57: Global MASTER-Net observations report
  87. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  88. GRB 251230A: GRANDMA/TAROT Early Detection
  89. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  90. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  91. EP251229a: Optical upper limit with Kinder observations
  92. GRB 251230A: 1.3m DFOT optical upper limit
  93. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  94. GRB 251230A: Swift-XRT refined Analysis
  95. GRB 251231A: Fermi GBM Final Real-time Localization
  96. GRB 251222A: Mondy Optical Observations
  97. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  98. GRB 251230A: Swift/UVOT detection
  99. GRB251230A: 7DT optical upper limits
  100. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2

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