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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"

45718 results found.

  1. GRB 260109B: Fermi GBM Final Real-time Localization
  2. GRB 260102A: Swift-XRT afterglow detection
  3. GRB 260109A: Fermi GBM Final Real-time Localization
  4. GRB 260104A: Swift-BAT refined analysis
  5. GRB 260101A: Swift-BAT refined analysis
  6. Swift GRB 251230A: Global MASTER-Net OT detection
  7. Fermi GRB 260107A: Global MASTER-Net observations report
  8. GRB 260102A: AbAO optical observations
  9. GRB 260107A: Fermi GBM Final Real-time Localization
  10. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  11. The EP-WXT trigger 01709251112 is likely a flaring star
  12. Fermi GRB 260105A: Global MASTER-Net observations report
  13. GRB 260105B: Fermi GBM Detection
  14. EP260105a: FTW optical observations
  15. EP260104a: FTW optical observations
  16. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  17. GRB 260105A: SVOM/GRM observation
  18. GRB 260105B: SVOM/GRM observation
  19. The EP-WXT trigger 01709251028 is likely a flaring star
  20. FRB 20251229A: COLIBRÍ optical upper limits
  21. Fermi GRB 260105B: Global MASTER-Net observations report
  22. EP260105a: SVOM/VT optical upperlimit
  23. GRB 260105B: Fermi GBM Final Real-time Localization
  24. GRB 260105A: Fermi GBM Final Real-time Localization
  25. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  26. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  27. EP260105a: LCO Optical Upper limit
  28. EP260104a: Global MASTER-Net observations report
  29. EP260104a: Einstein Probe detection of a fast X-ray transient
  30. GRB 260101A: COLIBRÍ optical upper limits
  31. EP260105a: Global MASTER-Net observations report
  32. EP260105a: Einstein Probe detection of an X-ray transient
  33. GRB 260103A: Insight-HXMT/HE detection
  34. GRB 260104A: COLIBRÍ optical upper limits
  35. GRB 260104C: Fermi GBM Final Real-time Localization
  36. Fermi GRB 260104B: Global MASTER-Net observations report
  37. Swift GRB 260104A: Global MASTER-Net observations report
  38. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  39. GRB 260104A: Swift-XRT refined Analysis
  40. GRB 260104A: Enhanced Swift-XRT position
  41. GRB 260101A: Swift/UVOT Detection
  42. GRB 260103A: GECAM-B observation of a burst
  43. GRB 260104B: Fermi GBM Final Localization
  44. GRB 260104A: Swift detection of a burst
  45. GRB 260103A: SVOM/GRM observation of a possible GRB
  46. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  47. GRB 260101A: COLIBRÍ optical observations
  48. SVOM GRB260103.08: Global MASTER-Net observations report
  49. GRB 260102B: Fermi GBM Final Real-time Localization
  50. SVOM GRB260102A: Global MASTER-Net observations report
  51. Fermi GBM Sub-Threshold Detection of GRB 260102A
  52. GRB 260102A: EP-FXT follow-up observation
  53. EP260101a: Global MASTER-Net observations report
  54. GRB 260102A: LCO optical upper limits
  55. GRB 260102A: Swift-XRT observations
  56. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  57. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  58. GRB 251230A / EP251230a: GECAM-B detection
  59. GRB 260102A: SVOM/VT optical counterpart
  60. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  61. GRB 260102A: Swift ToO 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: GECAM-B detection
  66. GRB 260101A: NOT spectroscopic observations
  67. GRB 260101A: SVOM/GRM observation
  68. GRB 260101A: Swift-XRT refined Analysis
  69. Swift GRB 260101A: Global MASTER-Net observations report
  70. GRB 260101A: Enhanced Swift-XRT position
  71. EP260101a: Einstein Probe detection of an X-ray transient
  72. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  73. GRB 260101A: LCO detection of the optical counterpart
  74. GRB 260101A: Swift detection of a burst with an optical counterpart
  75. GRB 260101A: Fermi GBM Final Real-time Localization
  76. SVOM GRB251231.57: Global MASTER-Net observations report
  77. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  78. GRB 251230A: GRANDMA/TAROT Early Detection
  79. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  80. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  81. EP251229a: Optical upper limit with Kinder observations
  82. GRB 251230A: 1.3m DFOT optical upper limit
  83. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  84. GRB 251230A: Swift-XRT refined Analysis
  85. GRB 251231A: Fermi GBM Final Real-time Localization
  86. GRB 251222A: Mondy Optical Observations
  87. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  88. GRB 251230A: Swift/UVOT detection
  89. GRB251230A: 7DT optical upper limits
  90. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  91. EP251229a: BOOTES-2 early optical upper limit
  92. GRB 251230A: GOTO optical upper limit
  93. EP251229a: NOT optical upper limits
  94. GRB 251230A / EP251230a: SVOM/VT optical observation
  95. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  96. GRB 251230A: Enhanced Swift-XRT position
  97. GRB 251230A: Early optical counterpart detection by LCO.
  98. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  99. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  100. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient

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