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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"

29100 results found.

  1. GRB 260105B: Fermi GBM Final Real-time Localization
  2. GRB 260105A: Fermi GBM Final Real-time Localization
  3. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  4. EP260105a: LCO Optical Upper limit
  5. EP260104a: Global MASTER-Net observations report
  6. GRB 260101A: COLIBRÍ optical upper limits
  7. EP260105a: Global MASTER-Net observations report
  8. GRB 260104A: COLIBRÍ optical upper limits
  9. GRB 260104C: Fermi GBM Final Real-time Localization
  10. Fermi GRB 260104B: Global MASTER-Net observations report
  11. Swift GRB 260104A: Global MASTER-Net observations report
  12. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  13. GRB 260104A: Swift-XRT refined Analysis
  14. GRB 260101A: Swift/UVOT Detection
  15. GRB 260104B: Fermi GBM Final Localization
  16. GRB 260104A: Swift detection of a burst
  17. GRB 260103A: SVOM/GRM observation of a possible GRB
  18. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  19. GRB 260101A: COLIBRÍ optical observations
  20. SVOM GRB260103.08: Global MASTER-Net observations report
  21. GRB 260102B: Fermi GBM Final Real-time Localization
  22. SVOM GRB260102A: Global MASTER-Net observations report
  23. Fermi GBM Sub-Threshold Detection of GRB 260102A
  24. GRB 260102A: EP-FXT follow-up observation
  25. EP260101a: Global MASTER-Net observations report
  26. GRB 260102A: LCO optical upper limits
  27. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  28. Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
  29. GRB 260102A: SVOM/VT optical counterpart
  30. GRB 260101A: Fermi GBM Observation
  31. GRB 260102A: SVOM detection of a burst
  32. GRB 260101A: GECAM-B detection
  33. GRB 260101A: NOT spectroscopic observations
  34. GRB 260101A: SVOM/GRM observation
  35. GRB 260101A: Swift-XRT refined Analysis
  36. Swift GRB 260101A: Global MASTER-Net observations report
  37. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  38. GRB 260101A: LCO detection of the optical counterpart
  39. GRB 260101A: Swift detection of a burst with an optical counterpart
  40. GRB 260101A: Fermi GBM Final Real-time Localization
  41. SVOM GRB251231.57: Global MASTER-Net observations report
  42. GRB 251230A: GRANDMA/TAROT Early Detection
  43. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  44. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  45. EP251229a: Optical upper limit with Kinder observations
  46. GRB 251230A: 1.3m DFOT optical upper limit
  47. Fermi Gamma-ray Burst Monitor trigger 788833547/251231018 is not a GRB
  48. GRB 251230A: Swift-XRT refined Analysis
  49. GRB 251231A: Fermi GBM Final Real-time Localization
  50. GRB 251222A: Mondy Optical Observations
  51. GRB 251230A: Swift/UVOT detection
  52. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  53. GRB 251230A: GOTO optical upper limit
  54. EP251229a: NOT optical upper limits
  55. GRB 251230A / EP251230a: SVOM/VT optical observation
  56. GRB 251230A: Early optical counterpart detection by LCO.
  57. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  58. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  59. Swift GRB 251230A: Global MASTER-Net observations report
  60. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  61. EP251229a: Global MASTER-Net observations report
  62. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  63. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  64. Fermi GRB 251228A: Global MASTER-Net observations report
  65. The EP-WXT trigger 01709250662 is likely a flaring star
  66. GRB 251228A: Fermi GBM Final Real-time Localization
  67. GRB 251226A: SVOM/GRM observation
  68. GRB 251226A: GECAM-B detection
  69. SVOM GRB251227.07: Global MASTER-Net observations report
  70. The EP-WXT trigger 01709250617 is likely a flaring star
  71. IceCube Alert 251225.84: Global MASTER-Net observations report
  72. IceCube-251225A - IceCube observation of a high-energy neutrino candidate track-like event
  73. Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
  74. GRB 251222A: NUTTelA-TAO Early Measurements
  75. GRB 251222A/EP251222b: Optical detection with Kinder observations
  76. EP251222a: Optical upper limit with Kinder observations
  77. GRB 251221A: Swift-BAT refined analysis
  78. GRB 251222A/EP251222b: FTW optical and NIR observations
  79. EP251222a: FTW optical and NIR observations
  80. GRB 251205A: Kilonova-Catcher optical afterglow detection
  81. GRB 251222A: AbAO optical observations
  82. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  83. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  84. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  85. GRB 251222A: ZTSH BVRI optical observations
  86. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  87. GRB 251222A: Continued 1.3m DFOT optical observation
  88. EP251220a: 3.6m DOT optical afterglow detection
  89. GRB 251222A: Fermi GBM Observation
  90. EP251220a: CrAO ZTSh optical observations
  91. EP251221a: PRIME upper limit
  92. EP251222a: Global MASTER-Net observations report
  93. GRB 251222A / EP251222b: GECAM-B observation
  94. EP251221a: Liverpool Telescope upper limits
  95. Konus-Wind detection of GRB 251222A / EP251222b
  96. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  97. EP251222a: NTT/ULTRACAM optical observations
  98. EP251222a: GOTO optical upper limit
  99. GRB 251222A / EP251222b: GOTO optical counterpart detection
  100. GRB 251222A / EP251222b: LCO optical observations

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