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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"

39266 results found.

  1. GRB 260109A: Fermi GBM Final Real-time Localization
  2. GRB 260104A: Swift-BAT refined analysis
  3. GRB 260101A: Swift-BAT refined analysis
  4. Swift GRB 251230A: Global MASTER-Net OT detection
  5. Fermi GRB 260107A: Global MASTER-Net observations report
  6. GRB 260102A: AbAO optical observations
  7. GRB 260107A: Fermi GBM Final Real-time Localization
  8. Fermi GRB 260105A: Global MASTER-Net observations report
  9. GRB 260105B: Fermi GBM Detection
  10. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  11. GRB 260105A: SVOM/GRM observation
  12. GRB 260105B: SVOM/GRM observation
  13. FRB 20251229A: COLIBRÍ optical upper limits
  14. Fermi GRB 260105B: Global MASTER-Net observations report
  15. GRB 260105B: Fermi GBM Final Real-time Localization
  16. GRB 260105A: Fermi GBM Final Real-time Localization
  17. EP260104a: Global MASTER-Net observations report
  18. GRB 260101A: COLIBRÍ optical upper limits
  19. EP260105a: Global MASTER-Net observations report
  20. GRB 260103A: Insight-HXMT/HE detection
  21. GRB 260104A: COLIBRÍ optical upper limits
  22. GRB 260104C: Fermi GBM Final Real-time Localization
  23. Fermi GRB 260104B: Global MASTER-Net observations report
  24. Swift GRB 260104A: Global MASTER-Net observations report
  25. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  26. GRB 260104A: Swift-XRT refined Analysis
  27. GRB 260104A: Enhanced Swift-XRT position
  28. GRB 260101A: Swift/UVOT Detection
  29. GRB 260103A: GECAM-B observation of a burst
  30. GRB 260104B: Fermi GBM Final Localization
  31. GRB 260104A: Swift detection of a burst
  32. GRB 260103A: SVOM/GRM observation of a possible GRB
  33. GRB 260101A: COLIBRÍ optical observations
  34. SVOM GRB260103.08: Global MASTER-Net observations report
  35. GRB 260102B: Fermi GBM Final Real-time Localization
  36. SVOM GRB260102A: Global MASTER-Net observations report
  37. Fermi GBM Sub-Threshold Detection of GRB 260102A
  38. GRB 260102A: EP-FXT follow-up observation
  39. EP260101a: Global MASTER-Net observations report
  40. GRB 260102A: LCO optical upper limits
  41. GRB 260102A: Swift-XRT observations
  42. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  43. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  44. GRB 251230A / EP251230a: GECAM-B detection
  45. GRB 260102A: SVOM/VT optical counterpart
  46. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  47. GRB 260102A: Swift ToO observations
  48. GRB 260101A: Fermi GBM Observation
  49. GRB 260102A: SVOM detection of a burst
  50. GRB 260101A: GECAM-B detection
  51. GRB 260101A: NOT spectroscopic observations
  52. GRB 260101A: SVOM/GRM observation
  53. GRB 260101A: Swift-XRT refined Analysis
  54. Swift GRB 260101A: Global MASTER-Net observations report
  55. GRB 260101A: Enhanced Swift-XRT position
  56. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  57. GRB 260101A: LCO detection of the optical counterpart
  58. GRB 260101A: Swift detection of a burst with an optical counterpart
  59. GRB 260101A: Fermi GBM Final Real-time Localization
  60. SVOM GRB251231.57: Global MASTER-Net observations report
  61. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  62. GRB 251230A: GRANDMA/TAROT Early Detection
  63. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  64. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  65. GRB 251230A: 1.3m DFOT optical upper limit
  66. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  67. GRB 251230A: Swift-XRT refined Analysis
  68. GRB 251231A: Fermi GBM Final Real-time Localization
  69. GRB 251222A: Mondy Optical Observations
  70. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  71. GRB 251230A: Swift/UVOT detection
  72. GRB251230A: 7DT optical upper limits
  73. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  74. GRB 251230A: GOTO optical upper limit
  75. GRB 251230A / EP251230a: SVOM/VT optical observation
  76. GRB 251230A: Enhanced Swift-XRT position
  77. GRB 251230A: Early optical counterpart detection by LCO.
  78. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  79. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  80. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  81. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  82. Swift GRB 251230A: Global MASTER-Net observations report
  83. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  84. EP251229a: Global MASTER-Net observations report
  85. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  86. GRB 251226A: Glowbug gamma-ray detection
  87. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  88. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  89. Fermi GRB 251228A: Global MASTER-Net observations report
  90. GRB 251228A: Fermi GBM Final Real-time Localization
  91. GRB 251226A: SVOM/GRM observation
  92. GRB 251226A: GECAM-B detection
  93. SVOM GRB251227.07: Global MASTER-Net observations report
  94. IceCube Alert 251225.84: Global MASTER-Net observations report
  95. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  96. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  97. GRB 251222A: NUTTelA-TAO Early Measurements
  98. GRB 251222A/EP251222b: Optical detection with Kinder observations
  99. GRB 251221A: Swift-BAT refined analysis
  100. GRB 251222A/EP251222b: FTW optical and NIR observations

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