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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"

28047 results found.

  1. GRB 260114A : MITSuME Akeno optical upper limits
  2. GRB 260114A: COLIBRÍ optical upper limits
  3. GRB 260114A: TNG NIR upper limit
  4. GRB 260114A: NOT optical observations
  5. GRB 260114A: SVOM/GRM observation of a short burst
  6. Swift GRB 260114A: Global MASTER-Net observations report
  7. GRB 260114A: Mondy optical observations
  8. GRB 260114A: GMG Optical Observation
  9. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  10. GRB 260114A: Swift detection of a short burst
  11. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  12. IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
  13. Swift GRB260113.43: Global MASTER-Net observations report
  14. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  15. EP260110a: TRT optical upper limits
  16. Konus-Wind detection of GRB 260101A
  17. GRB 260111A: Swift-XRT observations
  18. Swift Trigger 1439093: is probably not GRB 260113A
  19. GRB 260111A: COLIBRÍ optical afterglow candidate
  20. GRB 260111A: Fermi GBM Observation
  21. GRB 251230A: Mondy Optical Observations
  22. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  23. IceCube Alert 260111A: Global MASTER-Net observations report
  24. EP260110a: Global MASTER-Net observations report
  25. Fermi GRB 260111A: Global MASTER-Net observations report
  26. Swift trigger 1436759 is not an astrophysical event
  27. EP260110a: KAIT optical upper limit
  28. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  29. EP 260110a: COLIBRÍ optical observations
  30. EP260110a: SVOM/C-GFT upper limit
  31. EP260110a: Einstein Probe detection of an X-ray transient
  32. GRB 260109C: LCO optical upper limits
  33. GRB 260109C: Kilonova-Catcher optical upper limit
  34. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  35. Swift Trigger 1434591: possible GRB 260109C
  36. GRB 260102A: Swift-XRT afterglow detection
  37. GRB 260104A: Swift-BAT refined analysis
  38. GRB 260101A: Swift-BAT refined analysis
  39. Swift GRB 251230A: Global MASTER-Net OT detection
  40. Fermi GRB 260107A: Global MASTER-Net observations report
  41. GRB 260102A: AbAO optical observations
  42. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  43. Fermi GRB 260105A: Global MASTER-Net observations report
  44. GRB 260105B: Fermi GBM Detection
  45. GRB 260105B: BALROG localization (Fermi Trigger 789348101 / GRB 260105973)
  46. GRB 260105A: SVOM/GRM observation
  47. GRB 260105B: SVOM/GRM observation
  48. FRB 20251229A: COLIBRÍ optical upper limits
  49. Fermi GRB 260105B: Global MASTER-Net observations report
  50. FRB 20251229A: A potentially hyperactive repeating fast radio burst source
  51. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  52. EP260105a: LCO Optical Upper limit
  53. EP260104a: Global MASTER-Net observations report
  54. EP260104a: Einstein Probe detection of a fast X-ray transient
  55. GRB 260101A: COLIBRÍ optical upper limits
  56. EP260105a: Global MASTER-Net observations report
  57. EP260105a: Einstein Probe detection of an X-ray transient
  58. GRB 260104A: COLIBRÍ optical upper limits
  59. Fermi GRB 260104B: Global MASTER-Net observations report
  60. Swift GRB 260104A: Global MASTER-Net observations report
  61. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  62. GRB 260104A: Swift-XRT refined Analysis
  63. GRB 260104A: Enhanced Swift-XRT position
  64. GRB 260101A: Swift/UVOT Detection
  65. GRB 260103A: GECAM-B observation of a burst
  66. GRB 260104A: Swift detection of a burst
  67. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  68. GRB 260101A: COLIBRÍ optical observations
  69. SVOM GRB260103.08: Global MASTER-Net observations report
  70. SVOM GRB260102A: Global MASTER-Net observations report
  71. Fermi GBM Sub-Threshold Detection of GRB 260102A
  72. GRB 260102A: EP-FXT follow-up observation
  73. EP260101a: Global MASTER-Net observations report
  74. GRB 260102A: LCO optical upper limits
  75. GRB 260102A: Swift-XRT observations
  76. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  77. GRB 260101A: Fermi GBM Observation
  78. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  79. GRB 260102A: SVOM detection of a burst
  80. GRB 260101A: NOT spectroscopic observations
  81. GRB 260101A: SVOM/GRM observation
  82. GRB 260101A: Swift-XRT refined Analysis
  83. Swift GRB 260101A: Global MASTER-Net observations report
  84. GRB 260101A: Enhanced Swift-XRT position
  85. EP260101a: Einstein Probe detection of an X-ray transient
  86. GRB 260101A: LCO detection of the optical counterpart
  87. GRB 260101A: Swift detection of a burst with an optical counterpart
  88. GRB 260101A: Fermi GBM Final Real-time Localization
  89. SVOM GRB251231.57: Global MASTER-Net observations report
  90. GRB 251230A: GRANDMA/TAROT Early Detection
  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. GRB 251230A: Swift-XRT refined Analysis
  95. GRB 251222A: Mondy Optical Observations
  96. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  97. GRB 251230A: Swift/UVOT detection
  98. GRB251230A: 7DT optical upper limits
  99. GRB 251230A: GOTO optical upper limit
  100. EP251229a: NOT optical upper limits

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